If 10 years ago many people could only find LEDs in expensive equipment, now this product is ubiquitous. The cost of LEDs has decreased significantly in recent years, so their use in many areas of technology is constantly growing. Just 3 years ago, few people could afford to buy, for example, a flashlight that glows not with an incandescent lamp, but with LEDs. Now this problem can be easily solved. However, not all options are good. There are often cheap fakes on the market in which the LEDs quickly go out and burn out, so buying a ready-made unit is not always justified. Making an LED flashlight with your own hands is not so difficult now.
This design will likely be more durable than a store-bought flashlight. In addition, it can not only be powered by batteries, but be rechargeable. This is a fairly convenient and economical option that you will surely like.
Required materials and tools
So, now directly about how to make a rechargeable LED flashlight with your own hands.
The tools and materials necessary for construction can be found in every home; in extreme cases, go to the nearest specialized store. Of course, an LED flashlight will need LEDs.
They have a number of advantages over conventional lamps. They are brighter, more economical, and shock-resistant. You will also need a battery that produces a voltage of 12 V. You can buy it in a store or pull it out of some unnecessary thing, such as an old radio-controlled toy.
For work you will need the following materials:
- pipe 5 cm, it is advisable to use PVC material;
- PVC glue;
- PVC threaded fitting - 2 pieces;
- PVC threaded plug;
- toggle switch;
- 12 V battery;
- a piece of foam;
- LED lamp;
- insulating tape.
You will need the following tools:
- soldering iron;
- solder;
- hacksaw;
- sandpaper;
- needle file;
- side cutters.
Now you can start creating.
Return to contents
How to make such a device?
First, select a battery. It should be shaped to fit into the PVC pipe. You can use not only the one-piece model, but also connect several finger or little finger batteries in series to get a total voltage of 12 V.
Now it’s worth including a toggle switch in the circuit. It can also be soldered. It must be open so that when it is closed, current will flow through the circuit.
The DIY lantern is ready. All that remains is to create a housing for it, because a lamp with a separate toggle switch and battery does not have a very aesthetic appearance. By the way, at this stage it is better to test whether everything is in working order in order to exclude alterations.
If everything is fine, you can start making the case. It is also very easy to make with your own hands from the remaining material.
First, you need to cut a hole in the fitting and process its edges with a file so that the lamp can be easily inserted.
Now you need to measure the length of the lamp along with the battery in order to know exactly how long the pipe that acts as the housing will be needed.
- Before installing the LED lamp in its rightful place, the edges must be lubricated with glue to subsequently avoid moisture getting inside the lamp. Now you can glue the fittings on both ends of the PVC tube to finally protect the lantern from moisture.
- The toggle switch must be installed on the side opposite to the lamp under the plug. Now you can wait a little until the glue dries and the flashlight is completely ready for use. Although this, of course, is not quite a flashlight, but some semblance of it, which needs to be brought to mind.
The fittings and plug will protect the flashlight well from moisture getting into it. This is very important, because water is something that greatly affects electronic devices, in particular, a flashlight is no exception. That is why in this version of the battery manufacturing, much attention is paid to the issue of protection from moisture.
For this, various devices and materials are used to prevent it from getting on electronic parts. You can, of course, neglect these safety measures, but there will be no guarantee of flawless operation for many months and years.
If everything is done correctly, the owner of the device will certainly be satisfied with his work.
For safety and the ability to continue active activities in the dark, a person needs artificial lighting. Primitive people pushed back the darkness by setting fire to tree branches, then they came up with a torch and a kerosene stove. And only after the invention of the prototype of a modern battery by the French inventor Georges Leclanche in 1866, and the incandescent lamp in 1879 by Thomson Edison, did David Mizell have the opportunity to patent the first electric flashlight in 1896.
Since then, nothing has changed in the electrical circuit of new flashlight samples, until in 1923, Russian scientist Oleg Vladimirovich Losev found a connection between luminescence in silicon carbide and the p-n junction, and in 1990, scientists managed to create an LED with greater luminous efficiency, allowing them to replace a light bulb incandescent The use of LEDs instead of incandescent lamps, due to the low energy consumption of LEDs, has made it possible to repeatedly increase the operating time of flashlights with the same capacity of batteries and accumulators, increase the reliability of flashlights and practically remove all restrictions on the area of their use.
The LED rechargeable flashlight that you see in the photograph came to me for repair with a complaint that the Chinese Lentel GL01 flashlight I bought the other day for $3 does not light, although the battery charge indicator is on.
The external inspection of the lantern made a positive impression. High-quality casting of the case, comfortable handle and switch. The plug rods for connecting to a household network for charging the battery are made retractable, eliminating the need to store the power cord.
Attention! When disassembling and repairing the flashlight, if it is connected to the network, you should be careful. Touching unprotected parts of your body to uninsulated wires and parts may result in electric shock.
How to disassemble the Lentel GL01 LED rechargeable flashlight
Although the flashlight was subject to warranty repair, remembering my experiences during the warranty repair of a faulty electric kettle (the kettle was expensive and the heating element in it burned out, so it was not possible to repair it with my own hands), I decided to do the repair myself.
It was easy to disassemble the lantern. It is enough to turn the ring that secures the protective glass a small angle counterclockwise and pull it off, then unscrew several screws. It turned out that the ring is fixed to the body using a bayonet connection.
After removing one of the halves of the flashlight body, access to all its components appeared. On the left in the photo you can see a printed circuit board with LEDs, to which a reflector (light reflector) is attached using three screws. In the center there is a black battery with unknown parameters; there is only a marking of the polarity of the terminals. To the right of the battery there is a printed circuit board for the charger and indication. On the right is a power plug with retractable rods.
Upon closer examination of the LEDs, it turned out that there were black spots or dots on the emitting surfaces of the crystals of all LEDs. It became clear even without checking the LEDs with a multimeter that the flashlight did not light due to their burnout.
There were also blackened areas on the crystals of two LEDs installed as backlight on the battery charging indication board. In LED lamps and strips, one LED usually fails, and acting as a fuse, it protects the others from burning out. And all nine LEDs in the flashlight failed at the same time. The voltage on the battery could not increase to a value that could damage the LEDs. To find out the reason, I had to draw an electrical circuit diagram.
Finding the cause of the flashlight failure
The electrical circuit of the flashlight consists of two functionally complete parts. The part of the circuit located to the left of switch SA1 acts as a charger. And the part of the circuit shown to the right of the switch provides the glow.
The charger works as follows. The voltage from the 220 V household network is supplied to the current-limiting capacitor C1, then to a bridge rectifier assembled on diodes VD1-VD4. From the rectifier, voltage is supplied to the battery terminals. Resistor R1 serves to discharge the capacitor after removing the flashlight plug from the network. This prevents electric shock from capacitor discharge in the event of your hand accidentally touching two pins of the plug at the same time.
LED HL1, connected in series with current-limiting resistor R2 in the opposite direction with the upper right diode of the bridge, as it turns out, always lights up when the plug is inserted into the network, even if the battery is faulty or disconnected from the circuit.
The operating mode switch SA1 is used to connect separate groups of LEDs to the battery. As you can see from the diagram, it turns out that if the flashlight is connected to the network for charging and the switch slide is in position 3 or 4, then the voltage from the battery charger also goes to the LEDs.
If a person turns on the flashlight and discovers that it does not work, and, not knowing that the switch slide must be set to the “off” position, about which nothing is said in the flashlight’s operating instructions, connects the flashlight to the network for charging, then at the expense If there is a voltage surge at the output of the charger, the LEDs will receive a voltage significantly higher than the calculated one. A current that exceeds the permissible current will flow through the LEDs and they will burn out. As an acid battery ages due to sulfation of the lead plates, the battery charge voltage increases, which also leads to LED burnout.
Another circuit solution that surprised me was the parallel connection of seven LEDs, which is unacceptable, since the current-voltage characteristics of even LEDs of the same type are different and therefore the current passing through the LEDs will also not be the same. For this reason, when choosing the value of resistor R4 based on the maximum permissible current flowing through the LEDs, one of them may overload and fail, and this will lead to an overcurrent of parallel-connected LEDs, and they will also burn out.
Rework (modernization) of the electrical circuit of the flashlight
It became obvious that the failure of the flashlight was due to errors made by the developers of its electrical circuit diagram. To repair the flashlight and prevent it from breaking again, you need to redo it, replacing the LEDs and making minor changes to the electrical circuit.
In order for the battery charge indicator to actually signal that it is charging, the HL1 LED must be connected in series with the battery. To light an LED, a current of several milliamps is required, and the current supplied by the charger should be about 100 mA.
To ensure these conditions, it is enough to disconnect the HL1-R2 chain from the circuit in the places indicated by red crosses and install an additional resistor Rd with a nominal value of 47 Ohms and a power of at least 0.5 W in parallel with it. The charge current flowing through Rd will create a voltage drop of about 3 V across it, which will provide the necessary current for the HL1 indicator to light. At the same time, the connection point between HL1 and Rd must be connected to pin 1 of switch SA1. In this simple way, it will be impossible to supply voltage from the charger to the LEDs EL1-EL10 while charging the battery.
To equalize the magnitude of the currents flowing through the LEDs EL3-EL10, it is necessary to exclude resistor R4 from the circuit and connect a separate resistor with a nominal value of 47-56 Ohms in series with each LED.
Electrical diagram after modification
Minor changes made to the circuit increased the information content of the charge indicator of an inexpensive Chinese LED flashlight and greatly increased its reliability. I hope that LED flashlight manufacturers will make changes to the electrical circuits of their products after reading this article.
After modernization, the electrical circuit diagram took the form as in the drawing above. If you need to illuminate the flashlight for a long time and do not require high brightness of its glow, you can additionally install a current-limiting resistor R5, thanks to which the operating time of the flashlight without recharging will double.
LED battery flashlight repair
After disassembly, the first thing you need to do is restore the functionality of the flashlight, and then start upgrading it.
Checking the LEDs with a multimeter confirmed that they were faulty. Therefore, all the LEDs had to be desoldered and the holes freed from solder to install new diodes.
Judging by its appearance, the board was equipped with tube LEDs from the HL-508H series with a diameter of 5 mm. LEDs of type HK5H4U from a linear LED lamp with similar technical characteristics were available. They came in handy for repairing the lantern. When soldering LEDs to the board, you must remember to observe polarity; the anode must be connected to the positive terminal of the battery or battery.
After replacing the LEDs, the PCB was connected to the circuit. The brightness of some LEDs was slightly different from others due to the common current-limiting resistor. To eliminate this drawback, it is necessary to remove resistor R4 and replace it with seven resistors, connected in series with each LED.
To select a resistor that ensures optimal operation of the LED, the dependence of the current flowing through the LED on the value of the series-connected resistance was measured at a voltage of 3.6 V, equal to the voltage of the flashlight battery.
Based on the conditions for using the flashlight (in case of interruptions in the power supply to the apartment), high brightness and illumination range were not required, so the resistor was chosen with a nominal value of 56 Ohms. With such a current-limiting resistor, the LED will operate in light mode, and energy consumption will be economical. If you need to squeeze out maximum brightness from the flashlight, then you should use a resistor, as can be seen from the table, with a nominal value of 33 Ohms and make two modes of operation of the flashlight by turning on another common current-limiting resistor (in the diagram R5) with a nominal value of 5.6 Ohms.
To connect a resistor in series with each LED, you must first prepare the printed circuit board. To do this, you need to cut any one current-carrying path on it, suitable for each LED, and make additional contact pads. The current-carrying paths on the board are protected by a layer of varnish, which must be scraped off with a knife blade to the copper, as in the photograph. Then tin the bare contact pads with solder.
It is better and more convenient to prepare a printed circuit board for mounting resistors and soldering them if the board is mounted on a standard reflector. In this case, the surface of the LED lenses will not be scratched, and it will be more convenient to work.
Connecting the diode board after repair and modernization to the flashlight battery showed that the brightness of all LEDs was sufficient for illumination and the same brightness.
Before I had time to repair the previous lamp, a second one was repaired, with the same fault. I didn’t find any information about the manufacturer or technical specifications on the flashlight body, but judging by the manufacturing style and the cause of the breakdown, the manufacturer is the same, Chinese Lentel.
Based on the date on the flashlight body and on the battery, it was possible to establish that the flashlight was already four years old and, according to its owner, the flashlight worked flawlessly. It is obvious that the flashlight lasted a long time thanks to the warning sign “Do not turn on while charging!” on a hinged lid covering a compartment in which a plug is hidden for connecting the flashlight to the mains for charging the battery.
In this flashlight model, the LEDs are included in the circuit according to the rules; a 33 Ohm resistor is installed in series with each one. The resistor value can be easily recognized by color coding using an online calculator. A check with a multimeter showed that all the LEDs were faulty, and the resistors were also broken.
An analysis of the cause of the failure of the LEDs showed that due to sulfation of the acid battery plates, its internal resistance increased and, as a result, its charging voltage increased several times. During charging, the flashlight was turned on, the current through the LEDs and resistors exceeded the limit, which led to their failure. I had to replace not only the LEDs, but also all the resistors. Based on the above-mentioned operating conditions of the flashlight, resistors with a nominal value of 47 Ohms were chosen for replacement. The resistor value for any type of LED can be calculated using an online calculator.
Redesign of the battery charging mode indication circuit
The flashlight has been repaired, and you can begin making changes to the battery charging indication circuit. To do this, it is necessary to cut the track on the printed circuit board of the charger and indication in such a way that the HL1-R2 chain on the LED side is disconnected from the circuit.
The lead-acid AGM battery was deeply discharged, and an attempt to charge it with a standard charger was unsuccessful. I had to charge the battery using a stationary power supply with a load current limiting function. A voltage of 30 V was applied to the battery, while at the first moment it consumed only a few mA of current. Over time, the current began to increase and after a few hours increased to 100 mA. After fully charging, the battery was installed in the flashlight.
Charging deeply discharged lead-acid AGM batteries with increased voltage as a result of long-term storage allows you to restore their functionality. I have tested the method on AGM batteries more than a dozen times. New batteries that do not want to be charged from standard chargers are restored to almost their original capacity when charged from a constant source at a voltage of 30 V.
The battery was discharged several times by turning on the flashlight in operating mode and charged using a standard charger. The measured charge current was 123 mA, with a voltage at the battery terminals of 6.9 V. Unfortunately, the battery was worn out and was enough to operate the flashlight for 2 hours. That is, the battery capacity was about 0.2 Ah and for long-term operation of the flashlight it is necessary to replace it.
The HL1-R2 chain on the printed circuit board was successfully placed, and it was necessary to cut only one current-carrying path at an angle, as in the photograph. The cutting width must be at least 1 mm. Calculation of the resistor value and testing in practice showed that for stable operation of the battery charging indicator, a 47 Ohm resistor with a power of at least 0.5 W is required.
The photo shows a printed circuit board with a soldered current-limiting resistor. After this modification, the battery charge indicator lights up only if the battery is actually charging.
Modernization of the operating mode switch
To complete the repair and modernization of the lights, it is necessary to resolder the wires at the switch terminals.
In models of flashlights being repaired, a four-position slide-type switch is used to turn on. The middle pin in the photo shown is general. When the switch slide is in the extreme left position, the common terminal is connected to the left terminal of the switch. When moving the switch slide from the extreme left position to one position to the right, its common pin is connected to the second pin and, with further movement of the slide, sequentially to pins 4 and 5.
To the middle common terminal (see photo above) you need to solder a wire coming from the positive terminal of the battery. Thus, it will be possible to connect the battery to a charger or LEDs. To the first pin you can solder the wire coming from the main board with LEDs, to the second you can solder a current-limiting resistor R5 of 5.6 Ohms to be able to switch the flashlight to an energy-saving operating mode. Solder the conductor coming from the charger to the rightmost pin. This will prevent you from turning on the flashlight while the battery is charging.
Repair and modernization
LED rechargeable spotlight "Foton PB-0303"
I received another copy of a series of Chinese-made LED flashlights called the Photon PB-0303 LED spotlight for repair. The flashlight did not respond when the power button was pressed; an attempt to charge the flashlight battery using a charger was unsuccessful.
The flashlight is powerful, expensive, costs about $20. According to the manufacturer, the luminous flux of the flashlight reaches 200 meters, the body is made of impact-resistant ABS plastic, and the kit includes a separate charger and a shoulder strap.
The Photon LED flashlight has good maintainability. To gain access to the electrical circuit, simply unscrew the plastic ring holding the protective glass, rotating the ring counterclockwise when looking at the LEDs.
When repairing any electrical appliances, troubleshooting always starts with the power source. Therefore, the first step was to measure the voltage at the terminals of the acid battery using a multimeter turned on in mode. It was 2.3 V, instead of the required 4.4 V. The battery was completely discharged.
When connecting the charger, the voltage at the battery terminals did not change, it became obvious that the charger was not working. The flashlight was used until the battery was completely discharged, and then it was not used for a long time, which led to a deep discharge of the battery.
It remains to check the serviceability of the LEDs and other elements. To do this, the reflector was removed, for which six screws were unscrewed. On the printed circuit board there were only three LEDs, a chip (chip) in the form of a droplet, a transistor and a diode.
Five wires went from the board and battery into the handle. In order to understand their connection, it was necessary to disassemble it. To do this, use a Phillips screwdriver to unscrew the two screws inside the flashlight, which were located next to the hole into which the wires went.
To detach the flashlight handle from its body, it must be moved away from the mounting screws. This must be done carefully so as not to tear the wires off the board.
As it turned out, there were no radio-electronic elements in the pen. Two white wires were soldered to the terminals of the flashlight on/off button, and the rest to the connector for connecting the charger. A red wire was soldered to pin 1 of the connector (the numbering is conditional), the other end of which was soldered to the positive input of the printed circuit board. A blue-white conductor was soldered to the second contact, the other end of which was soldered to the negative pad of the printed circuit board. A green wire was soldered to pin 3, the second end of which was soldered to the negative terminal of the battery.
Electrical circuit diagram
Having dealt with the wires hidden in the handle, you can draw an electrical circuit diagram of the Photon flashlight.
From the negative terminal of the battery GB1, voltage is supplied to pin 3 of connector X1 and then from its pin 2 through a blue-white conductor it is supplied to the printed circuit board.
Connector X1 is designed in such a way that when the charger plug is not inserted into it, pins 2 and 3 are connected to each other. When the plug is inserted, pins 2 and 3 are disconnected. This ensures automatic disconnection of the electronic part of the circuit from the charger, eliminating the possibility of accidentally turning on the flashlight while charging the battery.
From the positive terminal of battery GB1, voltage is supplied to D1 (microcircuit-chip) and the emitter of a bipolar transistor type S8550. The CHIP performs only the function of a trigger, allowing a button to turn on or off the glow of EL LEDs (⌀8 mm, glow color - white, power 0.5 W, current consumption 100 mA, voltage drop 3 V.). When you first press the S1 button from the D1 chip, a positive voltage is applied to the base of the transistor Q1, it opens and the supply voltage is supplied to the LEDs EL1-EL3, the flashlight turns on. When you press button S1 again, the transistor closes and the flashlight turns off.
From a technical point of view, such a circuit solution is illiterate, since it increases the cost of the flashlight, reduces its reliability, and in addition, due to the voltage drop at the junction of transistor Q1, up to 20% of the battery capacity is lost. Such a circuit solution is justified if it is possible to adjust the brightness of the light beam. In this model, instead of a button, it was enough to install a mechanical switch.
It was surprising that in the circuit, LEDs EL1-EL3 are connected in parallel to the battery like incandescent light bulbs, without current-limiting elements. As a result, when turned on, a current passes through the LEDs, the magnitude of which is limited only by the internal resistance of the battery and when it is fully charged, the current may exceed the permissible value for the LEDs, which will lead to their failure.
Checking the functionality of the electrical circuit
To check the serviceability of the microcircuit, transistor and LEDs, a 4.4 V DC voltage was applied from an external power source with a current limiting function, maintaining polarity, directly to the power pins of the printed circuit board. The current limit value was set to 0.5 A.
After pressing the power button, the LEDs lit up. After pressing again, they went out. The LEDs and the microcircuit with the transistor turned out to be serviceable. All that remains is to figure out the battery and charger.
Acid battery recovery
Since the 1.7 A acid battery was completely discharged, and the standard charger was faulty, I decided to charge it from a stationary power supply. When connecting the battery for charging to a power supply with a set voltage of 9 V, the charging current was less than 1 mA. The voltage was increased to 30 V - the current increased to 5 mA, and after an hour at this voltage it was already 44 mA. Next, the voltage was reduced to 12 V, the current dropped to 7 mA. After 12 hours of charging the battery at a voltage of 12 V, the current rose to 100 mA, and the battery was charged with this current for 15 hours.
The temperature of the battery case was within normal limits, which indicated that the charging current was not used to generate heat, but to accumulate energy. After charging the battery and finalizing the circuit, which will be discussed below, tests were carried out. The flashlight with a restored battery illuminated continuously for 16 hours, after which the brightness of the beam began to decrease and therefore it was turned off.
Using the method described above, I had to repeatedly restore the functionality of deeply discharged small-sized acid batteries. As practice has shown, only serviceable batteries that have been forgotten for some time can be restored. Acid batteries that have exhausted their service life cannot be restored.
Charger repair
Measuring the voltage value with a multimeter at the contacts of the output connector of the charger showed its absence.
Judging by the sticker pasted on the adapter body, it was a power supply that outputs an unstabilized DC voltage of 12 V with a maximum load current of 0.5 A. There were no elements in the electrical circuit that limited the amount of charging current, so the question arose, why in the quality charger, did you use a regular power supply?
When the adapter was opened, a characteristic smell of burnt electrical wiring appeared, which indicated that the transformer winding had burned out.
A continuity test of the primary winding of the transformer showed that it was broken. After cutting the first layer of tape insulating the primary winding of the transformer, a thermal fuse was discovered that was designed for an operating temperature of 130°C. Testing showed that both the primary winding and the thermal fuse were faulty.
Repairing the adapter was not economically feasible, since it was necessary to rewind the primary winding of the transformer and install a new thermal fuse. I replaced it with a similar one that was on hand, with a DC voltage of 9 V. The flexible cord with a connector had to be resoldered from a burnt adapter.
The photo shows a drawing of the electrical circuit of a burnt-out power supply (adapter) of the Photon LED flashlight. The replacement adapter was assembled according to the same scheme, only with an output voltage of 9 V. This voltage is quite sufficient to provide the required battery charging current with a voltage of 4.4 V.
Just for fun, I connected the flashlight to a new power supply and measured the charging current. Its value was 620 mA, and this was at a voltage of 9 V. At a voltage of 12 V, the current was about 900 mA, significantly exceeding the load capacity of the adapter and the recommended battery charging current. For this reason, the primary winding of the transformer burned out due to overheating.
Finalization of the electrical circuit diagram
LED rechargeable flashlight "Photon"
To eliminate circuit violations in order to ensure reliable and long-term operation, changes were made to the flashlight circuit and the printed circuit board was modified.
The photo shows the electrical circuit diagram of the converted Photon LED flashlight. Additional installed radio elements are shown in blue. Resistor R2 limits the battery charging current to 120 mA. To increase the charging current, you need to reduce the resistor value. Resistors R3-R5 limit and equalize the current flowing through the LEDs EL1-EL3 when the flashlight is illuminated. The EL4 LED with a series-connected current-limiting resistor R1 is installed to indicate the battery charging process, since the developers of the flashlight did not take care of this.
To install current-limiting resistors on the board, the printed traces were cut, as shown in the photo. The charge current-limiting resistor R2 was soldered at one end to the contact pad, to which the positive wire coming from the charger had previously been soldered, and the soldered wire was soldered to the second terminal of the resistor. An additional wire (yellow in the photo) was soldered to the same contact pad, intended to connect the battery charging indicator.
Resistor R1 and indicator LED EL4 were placed in the flashlight handle, next to the connector for connecting the charger X1. The LED anode pin was soldered to pin 1 of connector X1, and a current-limiting resistor R1 was soldered to the second pin, the cathode of the LED. A wire (yellow in the photo) was soldered to the second terminal of the resistor, connecting it to the terminal of resistor R2, soldered to the printed circuit board. Resistor R2, for ease of installation, could have been placed in the flashlight handle, but since it heats up when charging, I decided to place it in a freer space.
When finalizing the circuit, MLT type resistors with a power of 0.25 W were used, except for R2, which is designed for 0.5 W. The EL4 LED is suitable for any type and color of light.
This photo shows the charging indicator while the battery is charging. Installing an indicator made it possible not only to monitor the battery charging process, but also to monitor the presence of voltage in the network, the health of the power supply and the reliability of its connection.
How to replace a burnt out CHIP
If suddenly a CHIP - a specialized unmarked microcircuit in a Photon LED flashlight, or a similar one assembled according to a similar circuit - fails, then to restore the flashlight's functionality it can be successfully replaced with a mechanical switch.
To do this, you need to remove the D1 chip from the board, and instead of the Q1 transistor switch, connect an ordinary mechanical switch, as shown in the above electrical diagram. The switch on the flashlight body can be installed instead of the S1 button or in any other suitable place.
Repair and alteration of LED flashlight
14Led Smartbuy Colorado
The Smartbuy Colorado LED flashlight stopped turning on, although three new AAA batteries were installed.
The waterproof body was made of anodized aluminum alloy and had a length of 12 cm. The flashlight looked stylish and was easy to use.
How to check batteries for suitability in an LED flashlight
Repair of any electrical device begins with checking the power source, therefore, despite the fact that new batteries were installed in the flashlight, repairs should begin with checking them. In the Smartbuy flashlight, the batteries are installed in a special container, in which they are connected in series using jumpers. In order to gain access to the flashlight batteries, you need to disassemble it by rotating the back cover counterclockwise.
Batteries must be installed in the container, observing the polarity indicated on it. The polarity is also indicated on the container, so it must be inserted into the flashlight body with the side on which the “+” sign is marked.
First of all, it is necessary to visually check all contacts of the container. If there are traces of oxides on them, then the contacts must be cleaned to a shine using sandpaper or the oxide must be scraped off with a knife blade. To prevent re-oxidation of the contacts, they can be lubricated with a thin layer of any machine oil.
Next you need to check the suitability of the batteries. To do this, touching the probes of a multimeter turned on in DC voltage measurement mode, you need to measure the voltage at the contacts of the container. Three batteries are connected in series and each of them should produce a voltage of 1.5 V, therefore the voltage at the terminals of the container should be 4.5 V.
If the voltage is less than specified, then it is necessary to check the correct polarity of the batteries in the container and measure the voltage of each of them individually. Perhaps only one of them sat down.
If everything is in order with the batteries, then you need to insert the container into the flashlight body, observing the polarity, screw on the cap and check its functionality. In this case, you need to pay attention to the spring in the cover, through which the supply voltage is transmitted to the flashlight body and from it directly to the LEDs. There should be no traces of corrosion on its end.
How to check if the switch is working properly
If the batteries are good and the contacts are clean, but the LEDs do not light, then you need to check the switch.
The Smartbuy Colorado flashlight has a sealed push-button switch with two fixed positions, closing the wire coming from the positive terminal of the battery container. When you press the switch button for the first time, its contacts close, and when you press it again, they open.
Since the flashlight contains batteries, you can also check the switch using a multimeter turned on in voltmeter mode. To do this, you need to rotate it counterclockwise, if you look at the LEDs, unscrew its front part and put it aside. Next, touch the body of the flashlight with one multimeter probe, and with the second touch the contact, which is located deep in the center of the plastic part shown in the photo.
The voltmeter should show a voltage of 4.5 V. If there is no voltage, press the switch button. If it is working properly, then voltage will appear. Otherwise, the switch needs to be repaired.
Checking the health of the LEDs
If the previous search steps failed to detect a fault, then at the next stage you need to check the reliability of the contacts supplying the supply voltage to the board with LEDs, the reliability of their soldering and serviceability.
A printed circuit board with LEDs sealed into it is fixed in the head of the flashlight using a steel spring-loaded ring, through which the supply voltage from the negative terminal of the battery container is simultaneously supplied to the LEDs along the flashlight body. The photo shows the ring from the side it presses against the printed circuit board.
The retaining ring is fixed quite tightly, and it was only possible to remove it using the device shown in the photo. You can bend such a hook from a steel strip with your own hands.
After removing the retaining ring, the printed circuit board with LEDs, which is shown in the photo, was easily removed from the head of the flashlight. The absence of current-limiting resistors immediately caught my eye; all 14 LEDs were connected in parallel and directly to the batteries via a switch. Connecting LEDs directly to a battery is unacceptable, since the amount of current flowing through the LEDs is limited only by the internal resistance of the batteries and can damage the LEDs. At best, it will greatly reduce their service life.
Since all the LEDs in the flashlight were connected in parallel, it was not possible to check them with a multimeter turned on in resistance measurement mode. Therefore, the printed circuit board was supplied with a DC supply voltage from an external source of 4.5 V with a current limit of 200 mA. All LEDs lit up. It became obvious that the problem with the flashlight was poor contact between the printed circuit board and the retaining ring.
Current consumption of LED flashlight
For fun, I measured the current consumption of LEDs from batteries when they were turned on without a current-limiting resistor.
The current was more than 627 mA. The flashlight is equipped with LEDs of type HL-508H, the operating current of which should not exceed 20 mA. 14 LEDs are connected in parallel, therefore, the total current consumption should not exceed 280 mA. Thus, the current flowing through the LEDs more than doubled the rated current.
Such a forced mode of LED operation is unacceptable, as it leads to overheating of the crystal, and as a result, premature failure of the LEDs. An additional disadvantage is that the batteries drain quickly. They will be enough, if the LEDs do not burn out first, for no more than an hour of operation.
The design of the flashlight did not allow soldering current-limiting resistors in series with each LED, so we had to install one common one for all LEDs. The resistor value had to be determined experimentally. To do this, the flashlight was powered by pants batteries and an ammeter was connected to the gap in the positive wire in series with a 5.1 Ohm resistor. The current was about 200 mA. When installing an 8.2 Ohm resistor, the current consumption was 160 mA, which, as tests showed, is quite sufficient for good lighting at a distance of at least 5 meters. The resistor did not get hot to the touch, so any power will do.
Redesign of the structure
After the study, it became obvious that for reliable and durable operation of the flashlight, it is necessary to additionally install a current-limiting resistor and duplicate the connection of the printed circuit board with the LEDs and the fixing ring with an additional conductor.
If previously it was necessary for the negative bus of the printed circuit board to touch the body of the flashlight, then due to the installation of the resistor, it was necessary to eliminate the contact. To do this, a corner was ground off from the printed circuit board along its entire circumference, from the side of the current-carrying paths, using a needle file.
To prevent the clamping ring from touching the current-carrying tracks when fixing the printed circuit board, four rubber insulators about two millimeters thick were glued onto it with Moment glue, as shown in the photograph. Insulators can be made from any dielectric material, such as plastic or thick cardboard.
The resistor was pre-soldered to the clamping ring, and a piece of wire was soldered to the outermost track of the printed circuit board. An insulating tube was placed over the conductor, and then the wire was soldered to the second terminal of the resistor.
After simply upgrading the flashlight with your own hands, it began to turn on stably and the light beam illuminated objects well at a distance of more than eight meters. Additionally, the battery life has more than tripled, and the reliability of the LEDs has increased many times over.
An analysis of the causes of failure of repaired Chinese LED lights showed that they all failed due to poorly designed electrical circuits. It remains only to find out whether this was done intentionally in order to save on components and shorten the life of the flashlights (so that more people would buy new ones), or as a result of the illiteracy of the developers. I am inclined to the first assumption.
Repair of LED flashlight RED 110
A flashlight with a built-in acid battery from the Chinese manufacturer RED brand was repaired. The flashlight had two emitters: one with a beam in the form of a narrow beam and one emitting diffused light.
The photo shows the appearance of the RED 110 flashlight. I immediately liked the flashlight. Convenient body shape, two modes of operation, a loop for hanging around the neck, a retractable plug for connecting to the mains for charging. In the flashlight, the diffused light LED section was shining, but the narrow beam was not.
To make the repair, we first unscrewed the black ring securing the reflector, and then unscrewed one self-tapping screw in the hinge area. The case easily separated into two halves. All parts were secured with self-tapping screws and were easily removed.
The charger circuit was made according to the classical scheme. From the network, through a current-limiting capacitor with a capacity of 1 μF, voltage was supplied to a rectifier bridge of four diodes and then to the battery terminals. The voltage from the battery to the narrow beam LED was supplied through a 460 Ohm current-limiting resistor.
All parts were mounted on a single-sided printed circuit board. The wires were soldered directly to the contact pads. The appearance of the printed circuit board is shown in the photograph.
10 side light LEDs were connected in parallel. The supply voltage was supplied to them through a common current-limiting resistor 3R3 (3.3 Ohms), although according to the rules, a separate resistor must be installed for each LED.
During an external inspection of the narrow beam LED, no defects were found. When power was supplied through the flashlight switch from the battery, voltage was present at the LED terminals, and it heated up. It became obvious that the crystal was broken, and this was confirmed by a continuity test with a multimeter. The resistance was 46 ohms for any connection of the probes to the LED terminals. The LED was faulty and needed to be replaced.
For ease of operation, the wires were unsoldered from the LED board. After freeing the LED leads from the solder, it turned out that the LED was tightly held by the entire plane of the reverse side on the printed circuit board. To separate it, we had to fix the board in the desktop temples. Next, place the sharp end of the knife at the junction of the LED and the board and lightly hit the knife handle with a hammer. The LED bounced off.
As usual, there were no markings on the LED housing. Therefore, it was necessary to determine its parameters and select a suitable replacement. Based on the overall dimensions of the LED, the battery voltage and the size of the current-limiting resistor, it was determined that a 1 W LED (current 350 mA, voltage drop 3 V) would be suitable for replacement. From the “Reference Table of Parameters of Popular SMD LEDs,” a white LED6000Am1W-A120 LED was selected for repair.
The printed circuit board on which the LED is installed is made of aluminum and at the same time serves to remove heat from the LED. Therefore, when installing it, it is necessary to ensure good thermal contact due to the tight fit of the rear plane of the LED to the printed circuit board. To do this, before sealing, thermal paste was applied to the contact areas of the surfaces, which is used when installing a radiator on a computer processor.
In order to ensure a tight fit of the LED plane to the board, you must first place it on the plane and slightly bend the leads upward so that they deviate from the plane by 0.5 mm. Next, tin the terminals with solder, apply thermal paste and install the LED on the board. Next, press it to the board (it’s convenient to do this with a screwdriver with the bit removed) and warm up the leads with a soldering iron. Next, remove the screwdriver, press it with a knife at the bend of the lead to the board and heat it with a soldering iron. After the solder has hardened, remove the knife. Due to the spring properties of the leads, the LED will be pressed tightly to the board.
When installing the LED, polarity must be observed. True, in this case, if a mistake is made, it will be possible to swap the voltage supply wires. The LED is soldered and you can check its operation and measure the current consumption and voltage drop.
The current flowing through the LED was 250 mA, the voltage drop was 3.2 V. Hence the power consumption (you need to multiply the current by the voltage) was 0.8 W. It was possible to increase the operating current of the LED by decreasing the resistance to 460 Ohms, but I did not do this, since the brightness of the glow was sufficient. But the LED will operate in a lighter mode, heat up less, and the flashlight’s operating time on a single charge will increase.
Checking the heating of the LED after operating for an hour showed effective heat dissipation. It heated up to a temperature of no more than 45°C. Sea trials showed a sufficient illumination range in the dark, more than 30 meters.
Replacing a lead acid battery in an LED flashlight
A failed acid battery in an LED flashlight can be replaced with either a similar acid battery or a lithium-ion (Li-ion) or nickel-metal hydride (Ni-MH) AA or AAA battery.
The Chinese lanterns being repaired were equipped with lead-acid AGM batteries of various sizes without markings with a voltage of 3.6 V. According to calculations, the capacity of these batteries ranges from 1.2 to 2 A×hours.
On sale you can find a similar acid battery from a Russian manufacturer for the 4V 1Ah Delta DT 401 UPS, which has an output voltage of 4 V with a capacity of 1 Ah, costing a couple of dollars. To replace it, simply re-solder the two wires, observing the polarity.
After several years of operation, the Lentel GL01 LED flashlight, the repair of which was described at the beginning of the article, was again brought to me for repair. Diagnostics showed that the acid battery had exhausted its service life.
A Delta DT 401 battery was purchased as a replacement, but it turned out that its geometric dimensions were larger than the faulty one. The standard flashlight battery had dimensions of 21x30x54 mm and was 10 mm higher. I had to modify the flashlight body. Therefore, before buying a new battery, make sure that it will fit into the flashlight body.
The stop in the case was removed and a part of the printed circuit board from which a resistor and one LED had previously been soldered off was cut off with a hacksaw.
After modification, the new battery installed well in the flashlight body and now, I hope, will last for many years.
Replacing a lead acid battery
AA or AAA batteries
If it is not possible to purchase a 4V 1Ah Delta DT 401 battery, then it can be successfully replaced with any three AA or AAA size AA or AAA pen-type batteries, which have a voltage of 1.2 V. For this, it is enough connect three batteries in series, observing polarity, using soldering wires. However, such a replacement is not economically feasible, since the cost of three high-quality AA-size AA batteries may exceed the cost of purchasing a new LED flashlight.
But where is the guarantee that there are no errors in the electrical circuit of the new LED flashlight, and it will not have to be modified either. Therefore, I believe that replacing the lead battery in a modified flashlight is advisable, as it will ensure reliable operation of the flashlight for several more years. And it will always be a pleasure to use a flashlight that you have repaired and modernized yourself.
A flashlight is a necessary thing when traveling to nature or to the countryside. At night, on a personal plot or near a tent, only it will create a ray of light in the dark kingdom. But even in a city apartment, sometimes you just can’t do without it. As a rule, it is difficult to get something small that has rolled under a bed or sofa without a flashlight. And although nowadays there are devices that are multifunctional and can be a source of light, some of our readers will probably want to know how to make a flashlight with their own hands. How to make a small device from scrap items will be discussed below.
Classic shape
The most convenient design, which in principle has remained unchanged for flashlights for many years, is the design containing:
- cylindrical body with batteries of the same shape;
- reflector with a light bulb at one end of the housing;
- removable cover at the other end of the housing.
And this design can be obtained using unnecessary household items. If you make a lantern with your own hands, you will, of course, not have the beauty of shapes like an industrial design. But it will be functional and you will get a lot of positive emotions from a working homemade product.
So, the main problem, which at first glance is difficult to solve, is the reflector. But it just seems complicated. In fact, we are surrounded by many objects that can become preparations for a whole range of reflectors of different sizes. These are ordinary plastic bottles. Their inner surface near the neck is very close in shape to that of a reflector made at the factory. And the lid seems to be created for mounting an LED in it, which is the best light source today. It is brighter and more economical than a miniature light bulb.
Making a reflector
The fact that you may not be able to find a tube of suitable dimensions for making a body is not a problem. It can be glued together from individual parts. For example, from unnecessary disposable ballpoint pens. To spring the contacts, you can use a spiral, which is used for binding pages, and the contacts can be made from thin sheet metal, the raw material for which will be a tin can. Therefore, we start by choosing a plastic bottle of the desired size and selecting the remaining elements. The smaller the bottle, the stiffer and stronger the reflector will be. The easiest way to fasten parts during assembly is using construction sealant.
So, let's start making a flashlight with our own hands. Using a sharp knife, cut off the neck and parabolic part of the body from the bottle and trim the edges with scissors.
For effective reflection, we use foil in which chocolate bars are wrapped. If its size is not enough, you can cut a larger piece from a roll of foil intended for baking products. To keep the foil on the surface, apply a thin layer of sealant. Then we press and level the foil over it. If she wrinkles, it doesn't matter. The main thing is that there are no swellings and that it follows the shape of the base.
We press the foil with our fingers and, smoothing out the unevenness, form the most even surface possible. Using scissors, trim the edges of the foil flush with the plastic base. Along the contour of the neck we make a cutout with a knife for the LED, which will subsequently be installed in this place on the socket.
We make it from the bottom of a bottle cap, cutting off the threaded edges with a sharp knife and, if necessary, trimming them with scissors. Then, using an awl or the tip of a knife to make two holes in the socket, we thread the legs of the LED through them, pressing its base against it. To correctly install the LED lamp in the center of the cover, you must select the correct distance between the holes according to the location of the legs in the base of the LED.
We bend the LED leads to the sides until they touch the edges of the socket. We attach the conductors to them by twisting. If the twisting turns out to be unreliable due to the properties of the wire cores or for other reasons, soldering is used. After attaching the wires, the leads are folded along the socket. It is recommended to check the performance of the received part using the batteries used in the flashlight.
Then we cut out a contact pad for the battery from a sheet of tin, which rests on the socket with the LED. By twisting or soldering we connect the pad - terminal with a shorter wire. We attach the terminal to a spring, which in turn is attached to the socket. To fasten the elements we use sealant.
Then we glue the socket with the LED into the reflector.
Bottom and case with batteries
The part of the flashlight body opposite the reflector is also made from a part of a bottle with a neck. But only from the very neck with the lid. A terminal made of a sheet of tin is glued to its inner wall. A wire is also attached to it. This wire and the second wire from the LED will be used to control the flashlight. The terminal is in contact with the battery, being pressed by a cap that is screwed onto the neck.
Two main parts are ready. Now we need to make a case for the batteries. To do this, we use dry and therefore no longer needed felt-tip pens. We leave only the body, which we shorten in length and trim along the axis along the ends, making two protrusions for gluing. Before cutting, make marks with a marker, applying the body of the felt-tip pen to the parts to be glued.
Apply glue to the protrusions and glue them to the reflector and the back, respectively.
Then we cut out the switch parts from the tin sheet. We mount the wires to them and glue the parts to the body.
We insert batteries into the flashlight and use it. This, of course, is not a factory-made flashlight with a high-quality reflector and high beam. But it is made with your own hands, it is your own product, which gives good low-level lighting and gives great pleasure, and money cannot buy it. Now you have a clear idea of how easy it is to make a lantern yourself.
Ready flashlight and light from it
As a rule, it is desirable to obtain maximum brightness from electric lamps. However, sometimes lighting is required that will minimally disrupt vision adaptation to darkness. As is known, the human eye can change its light sensitivity over a fairly wide range. This allows, on the one hand, to see at dusk and in poor lighting, and on the other hand, not to go blind on a bright sunny day. If you go out into the street from a well-lit room at night, almost nothing will be visible for the first moments, but gradually your eyes will adapt to the new conditions. Complete adaptation of vision to darkness takes about one hour, after which the eye reaches maximum sensitivity, which is 200 thousand times higher than during the day. Under such conditions, even short-term exposure to bright light (turning on a flashlight or car headlight) greatly reduces the sensitivity of the eyes. However, even with complete adaptation to the dark, it may be necessary, for example, to read a map, illuminate the instrument scale, etc., and this requires artificial lighting. Therefore, astronomy lovers, as well as everyone who needs to consider something, do not need a bright flashlight in poor lighting conditions.
When making an astronomical lantern, one should not strive for excessive miniaturization. The body of the astronomical flashlight should be light and large enough so that in poor lighting conditions it can be easily found (otherwise you will drop it under your feet and have to look for the flashlight for half an hour). A travel soap dish was used as the body. Switches should be such that they are easy to use by touch and with gloves.
The eye is maximally sensitive to light with a wavelength of 550 nm (green light), and in the dark the maximum sensitivity of the eye shifts towards short waves up to 510 nm (effect Purkinje). For this reason, it is preferable to use red LEDs in an astronomical flashlight rather than blue, or even more so green. The eyes are less sensitive to red light, which means red lighting will less disrupt adaptation to darkness.
In addition to the main lantern, you can make several simple beacons to illuminate various objects. The fact is that few astronomy lovers can afford to have a full-fledged amateur observatory. Most watch from the balcony. And in a tight space, and even in the dark, you can easily hook your foot and overwhelm the tripod of a telescope or camera. In addition, unexpectedly meeting in the dark with your knee against the corner of some drawer or bedside table, the same pleasure is small. Therefore, it is advisable to use the simplest mini flashlights to illuminate tripod legs, sharp corners of furniture, shelves with accessories, and so on. In principle, a simple LED attached with adhesive tape to a 3 V battery type is suitable for this purpose. 2032 or similar. But, firstly, without a current-limiting resistor, the LED glow is too bright, and secondly, even in the simplest flashlight it is advisable to have a switch. Guided by these considerations, several such beacons were made.
A reed switch paired with a magnet is used as a switch. The 3 V battery mount is homemade. A current-limiting resistor is connected in series with the LED; its value must be selected so that in the dark, when looking directly at the LED lens, the light does not blind the eyes even at close range. In different beacons, you can use LEDs of different colors to facilitate identification, while remembering that the eye does not have the same sensitivity to light with different wavelengths. Flashing LEDs can be used.
In addition, there are a couple more designs of simple LED lights. The designs described below were not specifically intended for astronomical purposes, but they can easily be adapted for such use.
A simple waterproof flashlight can be made using a film can. We will need: a new film can, a 3 V LED, 2-3 reed switches, a 3 V lithium battery 2032 , cotton wool (case filler), battery holder from an old flashlight. To ensure water resistance, it is necessary that there are no holes in the flashlight body. So, as a switch, you can use sealed contacts. For reliable operation, it is better to take 2-3 reed switches, since when turning along the longitudinal axis, the sensitivity of the reed switch changes. So, let's assemble the flashlight according to the diagram.
We bend the wires so that everything fits in the case, I filled the empty space with cotton wool so that nothing dangles. We place the circuit in the case. It is important that the film can be new, i.e. so that the lid closes as tightly as possible. Any magnet will work as a switch. A flashlight of this design continued to work after 10 hours in the water. The cotton wool remained dry. So, lying in a puddle for a long time will not harm such a device.
Surely radio amateurs have pads from failed 9 V Krona batteries. Based on such a block, you can assemble a simple flashlight that actually does not need a housing. An LED is connected to the contacts of the block through a current-limiting resistor.
On the outside, the LED and resistor are wrapped with several layers of insulating tape. When placed on the battery, the flashlight forms a single unit with it.
Thus, you can adapt almost any suitable housing and battery for a homemade flashlight, although below 3.5 V you will already need to install an LED. Thank you for your attention. Author Denev.
Discuss the article DIY LED FLASHLIGHTS
Making your own LED flashlight
LED flashlight with 3-volt converter for LED 0.3-1.5V 0.3-1.5
VLEDFlashLight
Typically, a blue or white LED requires 3 - 3.5v to operate; this circuit allows you to power a blue or white LED with low voltage from one AA battery.Normally, if you want to light up a blue or white LED you need to provide it with 3 - 3.5 V, like from a 3 V lithium coin cell.
Details:
Light-emitting diode
Ferrite ring (~10 mm diameter)
Wire for winding (20 cm)
1 kOhm resistor
N-P-N transistor
Battery
Parameters of the transformer used:
The winding going to the LED has ~45 turns, wound with 0.25mm wire.
The winding going to the base of the transistor has ~30 turns of 0.1mm wire.
The base resistor in this case has a resistance of about 2K.
Instead of R1, it is advisable to install a tuning resistor, and achieve a current through the diode of ~22 mA; with a fresh battery, measure its resistance, then replacing it with a constant resistor of the obtained value.
The assembled circuit should work immediately.
There are only 2 possible reasons why the scheme will not work.
1. the ends of the winding are mixed up.
2. too few turns of the base winding.
Generation disappears with the number of turns<15.
Place the wire pieces together and wrap them around the ring.
Connect the two ends of different wires together.
The circuit can be placed inside a suitable housing.
The introduction of such a circuit into a flashlight operating on 3V significantly extends the duration of its operation from one set of batteries.
Option to make the flashlight powered by one 1.5V battery.
The transistor and resistance are placed inside the ferrite ring
The white LED runs on a dead AAA battery.
Modernization option "flashlight - pen"
The excitation of the blocking oscillator shown in the diagram is achieved by transformer coupling at T1. The voltage pulses arising in the right (according to the circuit) winding are added to the voltage of the power source and are supplied to the LED VD1. Of course, it would be possible to eliminate the capacitor and resistor in the base circuit of the transistor, but then failure of VT1 and VD1 is possible when using branded batteries with low internal resistance. The resistor sets the operating mode of the transistor, and the capacitor passes the RF component.The circuit used a KT315 transistor (as the cheapest, but any other with a cutoff frequency of 200 MHz or more) and a super-bright LED were used. To make a transformer, you will need a ferrite ring (approximate size 10x6x3 and permeability of about 1000 HH). Wire diameter is about 0.2-0.3 mm. Two coils of 20 turns each are wound on the ring.
If there is no ring, then you can use a cylinder of similar volume and material. You just have to wind 60-100 turns for each of the coils.
Important point : you need to wind the coils in different directions.
Photos of the flashlight:
the switch is in the "fountain pen" button, and the gray metal cylinder conducts current.
We make a cylinder according to the standard size of the battery.
It can be made from paper, or use a piece of any rigid tube.
We make holes along the edges of the cylinder, wrap it with tinned wire, and pass the ends of the wire into the holes. We fix both ends, but leave a piece of conductor at one end so that we can connect the converter to the spiral.
A ferrite ring would not fit into the lantern, so a cylinder made of a similar material was used.
A cylinder made from an inductor from an old TV.
The first coil is about 60 turns.
Then the second one swings in the opposite direction again for 60 or so. The coils are held together with glue.
Assembling the converter:
Everything is located inside our case: We solder the transistor, the capacitor, the resistor, solder the spiral on the cylinder, and the coil. The current in the coil windings must go in different directions! That is, if you wound all the windings in one direction, then swap the leads of one of them, otherwise generation will not occur.
The result is the following:
We insert everything inside, and use nuts as side plugs and contacts.
We solder the coil leads to one of the nuts, and the VT1 emitter to the other. Glue it. We mark the conclusions: where we have the output from the coils we put “-”, where the output from the transistor with the coil we put “+” (so that everything is like in a battery).
Now you need to make a “lampodiode”.
Attention: There should be a minus LED on the base.
Assembly:
As is clear from the figure, the converter is a “substitute” for the second battery. But unlike it, it has three points of contact: with the plus of the battery, with the plus of the LED, and the common body (through the spiral).Its location in the battery compartment is specific: it must be in contact with the positive of the LED.
Modern flashlightwith LED operating mode powered by constant stabilized current.
The current stabilizer circuit works as follows:
When power is applied to the circuit, transistors T1 and T2 are locked, T3 is open, because an unlocking voltage is applied to its gate through resistor R3. Due to the presence of inductor L1 in the LED circuit, the current increases smoothly. As the current in the LED circuit increases, the voltage drop across the R5-R4 chain increases; as soon as it reaches approximately 0.4V, transistor T2 will open, followed by T1, which in turn will close the current switch T3. The increase in current stops, a self-induction current appears in the inductor, which begins to flow through diode D1 through the LED and a chain of resistors R5-R4. As soon as the current decreases below a certain threshold, transistors T1 and T2 will close, T3 will open, which will lead to a new cycle of energy accumulation in the inductor. In normal mode, the oscillatory process occurs at a frequency of the order of tens of kilohertz.
About details:
Instead of the IRF510 transistor, you can use the IRF530, or any n-channel field-effect switching transistor with a current of more than 3A and a voltage of more than 30 V.
Diode D1 must have a Schottky barrier for a current of more than 1A; if you install even a regular high-frequency type KD212, the efficiency will drop to 75-80%.
The inductor is homemade; it is wound with a wire no thinner than 0.6 mm, or better - with a bundle of several thinner wires. About 20-30 turns of wire per armor core B16-B18 are required with a non-magnetic gap of 0.1-0.2 mm or close from 2000NM ferrite. If possible, the thickness of the non-magnetic gap is selected experimentally according to the maximum efficiency of the device. Good results can be obtained with ferrites from imported inductors installed in switching power supplies, as well as in energy-saving lamps. Such cores have the appearance of a spool of thread and do not require a frame or a non-magnetic gap. Coils on toroidal cores made of pressed iron powder, which can be found in computer power supplies (the output filter inductors are wound on them), work very well. The non-magnetic gap in such cores is evenly distributed throughout the volume due to the production technology.
The same stabilizer circuit can be used in conjunction with other batteries and galvanic cell batteries with a voltage of 9 or 12 volts without any change in the circuit or cell ratings. The higher the supply voltage, the less current the flashlight will consume from the source, its efficiency will remain unchanged. The operating stabilization current is set by resistors R4 and R5.
If necessary, the current can be increased to 1A without the use of heat sinks on the parts, only by selecting the resistance of the setting resistors.
The battery charger can be left “original” or assembled according to any of the known schemes, or even used externally to reduce the weight of the flashlight.
LED flashlight from calculator B3-30
The converter is based on the circuit of the B3-30 calculator, the switching power supply of which uses a transformer only 5 mm thick and having two windings. Using a pulse transformer from an old calculator made it possible to create an economical LED flashlight.
The result is a very simple circuit.
The voltage converter is made according to the circuit of a single-cycle generator with inductive feedback on transistor VT1 and transformer T1. The pulse voltage from winding 1-2 (according to the circuit diagram of the B3-30 calculator) is rectified by diode VD1 and supplied to the ultra-bright LED HL1. Capacitor C3 filter. The design is based on a Chinese-made flashlight designed to install two AA batteries. The converter is mounted on a printed circuit board made of one-sided foil fiberglass 1.5 mm thickFig.2sizes that replace one battery and are inserted into the flashlight instead. A contact made of double-sided foil-coated fiberglass with a diameter of 15 mm is soldered to the end of the board, marked with a “+” sign; both sides are connected by a jumper and tinned with solder.After installing all the parts on the board, the “+” end contact and the T1 transformer are filled with hot-melt adhesive to increase strength. A variant of the lantern layout is shown inFig.3and in a particular case depends on the type of flashlight used. In my case, no modifications to the flashlight were required, the reflector has a contact ring to which the negative terminal of the printed circuit board is soldered, and the board itself is attached to the reflector using hot-melt adhesive. The printed circuit board assembly with the reflector is inserted instead of one battery and clamped with a lid.
The voltage converter uses small-sized parts. Resistors type MLT-0.125, capacitors C1 and C3 are imported, up to 5 mm high. Diode VD1 type 1N5817 with a Schottky barrier; in its absence, you can use any rectifier diode that has suitable parameters, preferably germanium due to the lower voltage drop across it. A correctly assembled converter does not need adjustment unless the transformer windings are reversed; otherwise, swap them. If the above transformer is not available, you can make it yourself. Winding is carried out on a ferrite ring of standard size K10*6*3 with a magnetic permeability of 1000-2000. Both windings are wound with PEV2 wire with a diameter of 0.31 to 0.44 mm. The primary winding has 6 turns, the secondary winding has 10 turns. After installing such a transformer on the board and checking its functionality, it should be secured to it using hot-melt adhesive.Tests of a flashlight with an AA battery are presented in Table 1.
During testing, the cheapest AA battery was used, costing only 3 rubles. The initial voltage under load was 1.28 V. At the output of the converter, the voltage measured on the super-bright LED was 2.83 V. The LED brand is unknown, diameter 10 mm. The total current consumption is 14 mA. The total operating time of the flashlight was 20 hours of continuous operation.
When the battery voltage drops below 1V, the brightness drops noticeably.
| Time, h | V battery, V | V conversion, V |
| 0 | 1,28 | 2,83 |
| 2 | 1,22 | 2,83 |
| 4 | 1,21 | 2,83 |
| 6 | 1,20 | 2,83 |
| 8 | 1,18 | 2,83 |
| 10 | 1,18 | 2.83 |
| 12 | 1,16 | 2.82 |
| 14 | 1,12 | 2.81 |
| 16 | 1,11 | 2.81 |
| 18 | 1,11 | 2.81 |
| 20 | 1,10 | 2.80 |
Homemade LED flashlight
The basis is a VARTA flashlight powered by two AA batteries:
Since diodes have a highly nonlinear current-voltage characteristic, it is necessary to equip the flashlight with a circuit for working with LEDs, which will ensure constant brightness as the battery discharges and will remain operational at the lowest possible supply voltage.
The basis of the voltage stabilizer is a micro-power step-up DC/DC converter MAX756.
According to the stated characteristics, it operates when the input voltage is reduced to 0.7V.
Connection diagram - typical:
Installation is carried out using a hinged method.Electrolytic capacitors - tantalum CHIP. They have low series resistance, which slightly improves efficiency. Schottky diode - SM5818. The chokes had to be connected in parallel, because there was no suitable denomination. Capacitor C2 - K10-17b. LEDs - super bright white L-53PWC “Kingbright”.
As can be seen in the figure, the entire circuit easily fits into the empty space of the light-emitting unit.
The output voltage of the stabilizer in this connection circuit is 3.3V. Since the voltage drop across the diodes in the nominal current range (15-30mA) is about 3.1V, the extra 200mV had to be extinguished by a resistor connected in series with the output.
In addition, a small series resistor improves load linearity and circuit stability. This is due to the fact that the diode has a negative TCR, and when warmed up, its forward voltage drop decreases, which leads to a sharp increase in the current through the diode when it is powered from a voltage source. There was no need to equalize the currents through parallel-connected diodes - no differences in brightness were observed by eye. Moreover, the diodes were of the same type and taken from the same box.
Now about the design of the light emitter. As can be seen in the photographs, the LEDs in the circuit are not tightly sealed, but are a removable part of the structure.
The original light bulb is gutted, and 4 cuts are made in the flange on 4 sides (one was already there). 4 LEDs are arranged symmetrically in a circle. The positive terminals (according to the diagram) are soldered onto the base near the cuts, and the negative terminals are inserted from the inside into the central hole of the base, cut off and also soldered. “Lampodiode” is inserted in place of a regular incandescent light bulb.Testing:
Stabilization of the output voltage (3.3V) continued until the supply voltage was reduced to ~1.2V. The load current was about 100mA (~ 25mA per diode). Then the output voltage began to decrease smoothly. The circuit has switched to a different operating mode, in which it no longer stabilizes, but outputs everything it can. In this mode, it worked up to a supply voltage of 0.5V! The output voltage dropped to 2.7V, and the current from 100mA to 8mA.
A little about efficiency.
The efficiency of the circuit is about 63% with fresh batteries. The fact is that the miniature chokes used in the circuit have an extremely high ohmic resistance - about 1.5 ohmsThe solution is a ring of µ-permalloy with a permeability of about 50.
40 turns of PEV-0.25 wire, in one layer - it turned out to be about 80 μG. The active resistance is about 0.2 Ohm, and the saturation current, according to calculations, is more than 3A. We change the output and input electrolyte to 100 μF, although without compromising efficiency it can be reduced to 47 μF.
LED flashlight circuiton a DC/DC converter from Analog Device - ADP1110.
Standard typical ADP1110 connection circuit.
This converter chip, according to the manufacturer’s specifications, is available in 8 versions:
| Model | Output voltage |
| ADP1110AN | Adjustable |
| ADP1110AR | Adjustable |
| ADP1110AN-3.3 | 3.3V |
| ADP1110AR-3.3 | 3.3V |
| ADP1110AN-5 | 5 V |
| ADP1110AR-5 | 5 V |
| ADP1110AN-12 | 12 V |
| ADP1110AR-12 | 12 V |
Microcircuits with the indices “N” and “R” differ only in the type of case: R is more compact.
If you bought a chip with index -3.3, you can skip the next paragraph and go to the “Details” item.
If not, I present to your attention another diagram:
It adds two parts that make it possible to obtain the required 3.3 volts at the output to power the LEDs.
The circuit can be improved by taking into account that LEDs require a current source rather than a voltage source to operate. Changes in the circuit so that it produces 60mA (20 for each diode), and the voltage of the diodes will be set to us automatically, the same 3.3-3.9V.
resistor R1 is used to measure current. The converter is designed in such a way that when the voltage at the FB (Feed Back) pin exceeds 0.22V, it will stop increasing the voltage and current, which means the resistance value R1 is easy to calculate R1 = 0.22V/In, in our case 3.6 Ohm. This circuit helps stabilize the current and automatically select the required voltage. Unfortunately, the voltage will drop across this resistance, which will lead to a decrease in efficiency, however, practice has shown that it is less than the excess that we chose in the first case. I measured the output voltage and it was 3.4 - 3.6V. The parameters of the diodes in such a connection should also be as identical as possible, otherwise the total current of 60 mA will not be distributed equally between them, and we will again get different luminosities.
Details
1. Any choke from 20 to 100 microhenry with a small (less than 0.4 Ohm) resistance is suitable. The diagram shows 47 μH. You can make it yourself - wind about 40 turns of PEV-0.25 wire on a ring of µ-permalloy with a permeability of about 50, size 10x4x5.
2. Schottky diode. 1N5818, 1N5819, 1N4148 or similar. Analog Device DOES NOT RECOMMEND the use of 1N4001
3. Capacitors. 47-100 microfarads at 6-10 volts. It is recommended to use tantalum.
4. Resistors. With a power of 0.125 watts and a resistance of 2 ohms, possibly 300 kohms and 2.2 kohms.
5. LEDs. L-53PWC - 4 pieces.
Voltage converter for powering the DFL-OSPW5111P white LED with a brightness of 30 cd at a current of 80 mA and a radiation pattern width of about 12°.
The current consumed from a 2.41V battery is 143mA; in this case, a current of about 70 mA flows through the LED at a voltage of 4.17 V. The converter operates at a frequency of 13 kHz, the electrical efficiency is about 0.85.
Transformer T1 is wound on a ring magnetic core of standard size K10x6x3 made of 2000NM ferrite.
The primary and secondary windings of the transformer are wound simultaneously (i.e., in four wires).
The primary winding contains - 2x41 turns of wire PEV-2 0.19,
The secondary winding contains 2x44 turns of PEV-2 0.16 wire.
After winding, the terminals of the windings are connected in accordance with the diagram.
Transistors KT529A of the p-n-p structure can be replaced with KT530A of the n-p-n structure, in this case it is necessary to change the polarity of the connection of the battery GB1 and the LED HL1.
The parts are placed on the reflector using wall-mounted installation. Please make sure that there is no contact between the parts and the tin plate of the flashlight, which supplies the minus of the GB1 battery. The transistors are fastened together with a thin brass clamp, which provides the necessary heat removal, and then glued to the reflector. The LED is placed instead of the incandescent lamp so that it protrudes 0.5... 1 mm from the socket for its installation. This improves heat dissipation from the LED and simplifies its installation.
When first turned on, power from the battery is supplied through a resistor with a resistance of 18...24 Ohms so as not to damage the transistors if the terminals of transformer T1 are incorrectly connected. If the LED does not light, it is necessary to swap the extreme terminals of the primary or secondary winding of the transformer. If this does not lead to success, check the serviceability of all elements and correct installation.
Voltage converter for powering an industrial LED flashlight.
Voltage converter to power LED flashlight
The diagram is taken from the Zetex manual for the use of ZXSC310 microcircuits.ZXSC310- LED driver chip.
FMMT 617 or FMMT 618.
Schottky diode- almost any brand.
Capacitors C1 = 2.2 µF and C2 = 10 µFfor surface mounting, 2.2 µF is the value recommended by the manufacturer, and C2 can be supplied from approximately 1 to 10 µF
68 microhenry inductor at 0.4 A
The inductance and resistor are installed on one side of the board (where there is no printing), all other parts are installed on the other. The only trick is to make a 150 milliohm resistor. It can be made from 0.1 mm iron wire, which can be obtained by unraveling a cable. The wire should be annealed with a lighter, thoroughly wiped with fine sandpaper, the ends should be tinned and a piece about 3 cm long should be soldered into the holes on the board. Next, during the setup process, you need to measure the current through the diodes, move the wire, while simultaneously heating the place where it is soldered to the board with a soldering iron.Thus, something like a rheostat is obtained. Having achieved a current of 20 mA, the soldering iron is removed and the unnecessary piece of wire is cut off. The author came up with a length of approximately 1 cm.
Flashlight on the power source
Rice. 3.Flashlight on a current source, with automatic equalization of current in LEDs, so that LEDs can have any range of parameters (LED VD2 sets the current, which is repeated by transistors VT2, VT3, so the currents in the branches will be the same)
The transistors, of course, should also be the same, but the spread of their parameters is not so critical, so you can take either discrete transistors, or if you can find three integrated transistors in one package, their parameters are as identical as possible. Play around with the placement of the LEDs, you need to choose an LED-transistor pair so that the output voltage is minimal, this will increase the efficiency.
The introduction of transistors leveled out the brightness, however, they have resistance and the voltage drops across them, which forces the converter to increase the output level to 4V. To reduce the voltage drop across the transistors, you can propose the circuit in Fig. 4, this is a modified current mirror, instead of the reference voltage Ube = 0.7V in the circuit in Fig. 3, you can use the 0.22V source built into the converter, and maintain it in the VT1 collector using an op-amp, also built into the converter.
Rice. 4.Flashlight on a current source, with automatic current equalization in LEDs, and with improved efficiency
Because The op-amp output is of the “open collector” type; it must be “pulled up” to the power supply, which is done by resistor R2. Resistances R3, R4 act as a voltage divider at point V2 by 2, so the opamp will maintain a voltage of 0.22*2 = 0.44V at point V2, which is 0.3V less than in the previous case. It is not possible to take an even smaller divider in order to lower the voltage at point V2. a bipolar transistor has a resistance Rke and during operation the voltage Uke will drop on it, in order for the transistor to work correctly V2-V1 must be greater than Uke, for our case 0.22V is quite enough. However, bipolar transistors can be replaced by field-effect transistors, in which the drain-source resistance is much lower, this will make it possible to reduce the divider, so as to make the difference V2-V1 very insignificant.
Throttle.The choke must be taken with minimal resistance, special attention should be paid to the maximum permissible current; it should be about 400 -1000 mA.
The rating doesn't matter as much as the maximum current, so Analog Devices recommends something between 33 and 180 µH. In this case, theoretically, if you do not pay attention to the dimensions, then the greater the inductance, the better in all respects. However, in practice this is not entirely true, because we do not have an ideal coil, it has active resistance and is not linear, in addition, the key transistor at low voltages will no longer produce 1.5A. Therefore, it is better to try several coils of different types, designs and different ratings in order to choose the coil with the highest efficiency and the lowest minimum input voltage, i.e. a coil with which the flashlight will glow for as long as possible.
Capacitors.C1 can be anything. It is better to take C2 with tantalum because It has low resistance, which increases efficiency.
Schottky diode.Any for current up to 1A, preferably with minimal resistance and minimal voltage drop.
Transistors.Any with a collector current of up to 30 mA, coefficient. current amplification of about 80 with a frequency of up to 100 MHz, KT318 is suitable.
LEDs.You can use white NSPW500BS with a glow of 8000 mcd from Power Light Systems.
Voltage transformerADP1110, or its replacement ADP1073, to use it, the circuit in Fig. 3 will need to be changed, take a 760 µH inductor, and R1 = 0.212/60mA = 3.5 Ohm.
Flashlight on ADP3000-ADJ
Options:
Power supply 2.8 - 10 V, efficiency approx. 75%, two brightness modes - full and half.
The current through the diodes is 27 mA, in half-brightness mode - 13 mA.
In order to obtain high efficiency, it is advisable to use chip components in the circuit.
A correctly assembled circuit does not need adjustment.
The disadvantage of the circuit is the high (1.25V) voltage at the FB input (pin 8).
Currently, DC/DC converters with an FB voltage of about 0.3V are produced, in particular from Maxim, on which it is possible to achieve an efficiency above 85%.
Flashlight diagram for Kr1446PN1.
Resistors R1 and R2 are a current sensor. Operational amplifier U2B - amplifies the voltage taken from the current sensor. Gain = R4 / R3 + 1 and is approximately 19. The gain required is such that when the current through resistors R1 and R2 is 60 mA, the output voltage turns on transistor Q1. By changing these resistors, you can set other stabilization current values.
In principle, there is no need to install an operational amplifier. Simply, instead of R1 and R2, one 10 Ohm resistor is installed, the signal from it is supplied through a 1 kOhm resistor to the base of the transistor and that’s it. But. This will lead to a decrease in efficiency. On a 10 Ohm resistor at a current of 60 mA, 0.6 Volt - 36 mW - is dissipated in vain. If an operational amplifier is used, the losses will be:
on a 0.5 Ohm resistor at a current of 60 mA = 1.8 mW + consumption of the op-amp itself is 0.02 mA let at 4 Volts = 0.08 mW
= 1.88 mW - significantly less than 36 mW.
About the components.
Any low-power op-amp with a low minimum supply voltage can work in place of the KR1446UD2; the OP193FS would be better suited, but it is quite expensive. Transistor in SOT23 package. A smaller polar capacitor - type SS for 10 Volts. The inductance of CW68 is 100 µH for a current of 710 mA. Although the cutoff current of the inverter is 1 A, it works fine. It achieved the best efficiency. I selected the LEDs based on the most equal voltage drop at a current of 20 mA. The flashlight is assembled in a housing for two AA batteries. I shortened the space for the batteries to fit the size of AAA batteries, and in the freed-up space I assembled this circuit using wall-mounted installation. A case that fits three AA batteries works well. You will need to install only two, and place the circuit in place of the third.
Efficiency of the resulting device.
Input U I P Output U I P Efficiency
Volt mA mW Volt mA mW %
3.03 90 273 3.53 62 219 80
1.78 180 320 3.53 62 219 68
1.28 290 371 3.53 62 219 59
Replacing the bulb of the “Zhuchek” flashlight with a module from the companyLuxeonLumiledLXHL-NW 98.
We get a dazzlingly bright flashlight, with a very light press (compared to a light bulb).
Rework scheme and module parameters.
StepUP DC-DC converters ADP1110 converters from Analog devices.
Power supply: 1 or 2 1.5V batteries, operability maintained up to Uinput = 0.9V
Consumption:
*with switch open S1 = 300mA
*with switch closed S1 = 110mA
LED Electronic Flashlight
Powered by just one AA or AAA AA battery on a microcircuit (KR1446PN1), which is a complete analogue of the MAX756 (MAX731) microcircuit and has almost identical characteristics.
The flashlight is based on a flashlight that uses two AA size AA batteries as a power source.
The converter board is placed in the flashlight instead of the second battery. A contact made of tinned sheet metal is soldered at one end of the board to power the circuit, and at the other there is an LED. A circle made of the same tin is placed on the LED terminals. The diameter of the circle should be slightly larger than the diameter of the reflector base (0.2-0.5 mm) into which the cartridge is inserted. One of the diode leads (negative) is soldered to the circle, the second (positive) goes through and is insulated with a piece of PVC or fluoroplastic tube. The purpose of the circle is twofold. It provides the structure with the necessary rigidity and at the same time serves to close the negative contact of the circuit. The lamp with the socket is removed from the lantern in advance and a circuit with an LED is placed in its place. Before installation on the board, the LED leads are shortened in such a way as to ensure a tight, play-free fit. Typically, the length of the leads (excluding soldering to the board) is equal to the length of the protruding part of the fully screwed-in lamp base.
The connection diagram between the board and the battery is shown in Fig. 9.2.
Next, the lantern is assembled and its functionality is checked. If the circuit is assembled correctly, then no settings are required.
The design uses standard installation elements: capacitors of the K50-35 type, EC-24 chokes with an inductance of 18-22 μH, LEDs with a brightness of 5-10 cd with a diameter of 5 or 10 mm. Of course, it is possible to use other LEDs with a supply voltage of 2.4-5 V. The circuit has sufficient power reserve and allows you to power even LEDs with a brightness of up to 25 cd!
About some test results of this design.
The flashlight modified in this way worked with a “fresh” battery without interruption, in the on state, for more than 20 hours! For comparison, the same flashlight in the “standard” configuration (that is, with a lamp and two “fresh” batteries from the same batch) worked for only 4 hours.
And one more important point. If you use rechargeable batteries in this design, it is easy to monitor the state of their discharge level. The fact is that the converter on the KR1446PN1 microcircuit starts stably at an input voltage of 0.8-0.9 V. And the glow of the LEDs is consistently bright until the voltage on the battery reaches this critical threshold. The lamp will, of course, still burn at this voltage, but we can hardly talk about it as a real light source.
Rice. 9.2Figure 9.3
The printed circuit board of the device is shown in Fig. 9.3, and the arrangement of elements is in Fig. 9.4.
Turning the flashlight on and off with one button
The circuit is assembled using a CD4013 D-trigger chip and an IRF630 field-effect transistor in the “off” mode. the current consumption of the circuit is practically 0. For stable operation of the D-trigger, a filter resistor and capacitor are connected to the input of the microcircuit; their function is to eliminate contact bounce. It is better not to connect unused pins of the microcircuit anywhere. The microcircuit operates from 2 to 12 volts; any powerful field-effect transistor can be used as a power switch, because The drain-source resistance of the field-effect transistor is negligible and does not load the output of the microcircuit.
CD4013A in SO-14 package, analogue of K561TM2, 564TM2
Simple generator circuits.
Allows you to power an LED with an ignition voltage of 2-3V from 1-1.5V. Short pulses of increased potential unlock the p-n junction. The efficiency of course decreases, but this device allows you to “squeeze” almost its entire resource from an autonomous power source.Wire 0.1 mm - 100-300 turns with a tap from the middle, wound on a toroidal ring.
LED flashlight with adjustable brightness and Beacon mode
The power supply of the microcircuit - generator with adjustable duty cycle (K561LE5 or 564LE5) that controls the electronic key, in the proposed device is carried out from a step-up voltage converter, which allows the flashlight to be powered from one 1.5 galvanic cell.The converter is made on transistors VT1, VT2 according to the circuit of a transformer self-oscillator with positive current feedback.
The generator circuit with adjustable duty cycle on the K561LE5 chip mentioned above has been slightly modified in order to improve the linearity of current regulation.
The minimum current consumption of a flashlight with six super-bright white LEDs L-53MWC from Kingbnght connected in parallel is 2.3 mA. The dependence of the current consumption on the number of LEDs is directly proportional.
The "Beacon" mode, when the LEDs flash brightly at a low frequency and then go out, is implemented by setting the brightness control to maximum and turning the flashlight on again. The desired frequency of light flashes is adjusted by selecting the capacitor SZ.
The performance of the flashlight is maintained when the voltage is reduced to 1.1v, although the brightness is significantly reduced
A field-effect transistor with an insulated gate KP501A (KR1014KT1V) is used as an electronic switch. According to the control circuit, it matches well with the K561LE5 microcircuit. The KP501A transistor has the following limit parameters: drain-source voltage - 240 V; gate-source voltage - 20 V. drain current - 0.18 A; power - 0.5 W
It is permissible to connect transistors in parallel, preferably from the same batch. Possible replacement - KP504 with any letter index. For IRF540 field-effect transistors, the supply voltage of the DD1 microcircuit. generated by the converter must be increased to 10 V
In a flashlight with six L-53MWC LEDs connected in parallel, the current consumption is approximately equal to 120 mA when the second transistor is connected in parallel to VT3 - 140 mA
Transformer T1 is wound on a ferrite ring 2000NM K10-6"4.5. The windings are wound in two wires, with the end of the first winding connected to the beginning of the second winding. The primary winding contains 2-10 turns, the secondary - 2 * 20 turns. Wire diameter - 0.37 mm. grade - PEV-2. The choke is wound on the same magnetic circuit without a gap with the same wire in one layer, the number of turns is 38. The inductance of the choke is 860 μH.
Converter circuit for LED from 0.4 to 3V- runs on one AAA battery. This flashlight increases the input voltage to the desired voltage using a simple DC-DC converter.
The output voltage is approximately 7 W (depending on the voltage of the installed LEDs).
Building the LED Head Lamp
As for the transformer in the DC-DC converter. You must do it yourself. The image shows how to assemble the transformer.
Another option for converters for LEDs _http://belza.cz/ledlight/ledm.htm
Flashlight with lead-acid sealed battery with charger.
Lead acid sealed batteries are the cheapest currently available. The electrolyte in them is in the form of a gel, so the batteries allow operation in any spatial position and do not produce any harmful fumes. They are characterized by great durability if deep discharge is not allowed. Theoretically, they are not afraid of overcharging, but this should not be abused. Rechargeable batteries can be recharged at any time without waiting for them to be completely discharged.
Lead-acid sealed batteries are suitable for use in portable flashlights used in the household, in summer cottages, and in production.
Fig.1. Electric torch circuit
The electrical circuit diagram of a flashlight with a charger for a 6-volt battery, which makes it possible in a simple way to prevent deep discharge of the battery and, thus, increase its service life, is shown in the figure. It contains a factory-made or home-made transformer power supply and a charging and switching device mounted in the flashlight body.
In the author's version, a standard unit intended for powering modems is used as a transformer unit. The output alternating voltage of the unit is 12 or 15 V, the load current is 1 A. Such units are also available with built-in rectifiers. They are also suitable for this purpose.
The alternating voltage from the transformer unit is supplied to the charging and switching device, which contains a plug for connecting the charger X2, a diode bridge VD1, a current stabilizer (DA1, R1, HL1), a battery GB, a toggle switch S1, an emergency switch S2, an incandescent lamp HL2. Each time the toggle switch S1 is turned on, the battery voltage is supplied to relay K1, its contacts K1.1 close, supplying current to the base of transistor VT1. The transistor turns on, passing current through the HL2 lamp. Turn off the flashlight by switching toggle switch S1 to its original position, in which the battery is disconnected from the winding of relay K1.
The permissible battery discharge voltage is selected at 4.5 V. It is determined by the switching voltage of relay K1. You can change the permissible value of the discharge voltage using resistor R2. As the resistor value increases, the permissible discharge voltage increases, and vice versa. If the battery voltage is below 4.5 V, the relay will not turn on, therefore, no voltage will be supplied to the base of the transistor VT1, which turns on the HL2 lamp. This means the battery needs charging. At a voltage of 4.5 V, the illumination produced by the flashlight is not bad. In case of emergency, you can turn on the flashlight at low voltage with the S2 button, provided that you first turn on the S1 toggle switch.
A constant voltage can also be supplied to the input of the charger-switching device, without paying attention to the polarity of the connected devices.
To switch the flashlight to charging mode, you need to connect the X1 socket of the transformer block to the X2 plug located on the flashlight body, and then connect the plug (not shown in the figure) of the transformer block to a 220 V network.
In this embodiment, a battery with a capacity of 4.2 Ah is used. Therefore, it can be charged with a current of 0.42 A. The battery is charged using direct current. The current stabilizer contains only three parts: an integrated voltage stabilizer DA1 type KR142EN5A or imported 7805, an LED HL1 and a resistor R1. The LED, in addition to working as a current stabilizer, also serves as an indicator of the battery charging mode.
Setting up the flashlight's electrical circuit comes down to adjusting the battery charging current. The charging current (in amperes) is usually chosen to be ten times less than the numerical value of the battery capacity (in ampere-hours).
To configure it, it is best to assemble the current stabilizer circuit separately. Instead of a battery load, connect an ammeter with a current of 2...5 A to the connection point between the cathode of the LED and resistor R1. By selecting resistor R1, set the calculated charge current using the ammeter.
Relay K1 – reed switch RES64, passport RS4.569.724. The HL2 lamp consumes approximately 1A current.
The KT829 transistor can be used with any letter index. These transistors are composite and have a high current gain of 750. This should be taken into account in case of replacement.
In the author's version, the DA1 chip is installed on a standard finned radiator with dimensions of 40x50x30 mm. Resistor R1 consists of two 12 W wirewound resistors connected in series.
Scheme:
LED FLASHLIGHT REPAIR
Part ratings (C, D, R)C = 1 µF. R1 = 470 kOhm. R2 = 22 kOhm.
1D, 2D - KD105A (permissible voltage 400V, maximum current 300 mA.)
Provides:
charging current = 65 - 70mA.
voltage = 3.6V.
LED-Treiber PR4401 SOT23
Here you can see what the results of the experiment led to.
The circuit presented to your attention was used to power an LED flashlight, recharge a mobile phone from two metal hydrite batteries, and when creating a microcontroller device, a radio microphone. In each case, the operation of the circuit was flawless. The list where you can use the MAX1674 can go on for a long time.
The easiest way to get a more or less stable current through an LED is to connect it to an unstabilized power supply circuit through a resistor. It must be taken into account that the supply voltage must be at least twice the operating voltage of the LED. The current through the LED is calculated by the formula:
I led = (Umax. power supply - U working diode) : R1
This scheme is extremely simple and in many cases is justified, but it should be used where there is no need to save electricity and there are no high requirements for reliability.
More stable circuits based on linear stabilizers:
It is better to choose adjustable or fixed voltage stabilizers as stabilizers, but it should be as close as possible to the voltage on the LED or a chain of series-connected LEDs.
Stabilizers like LM 317 are very suitable.
German text:
iel war es, mit nur einer NiCd-Zelle (AAA, 250mAh) eine der neuen ultrahellen LEDs mit 5600mCd zu betreiben. Diese LEDs benötigen 3.6V/20mA. Ich habe Ihre Schaltung zunächst unverändert übernommen, als Induktivität hatte ich allerdings nur eine mit 1,4mH zur Hand. Die Schaltung lief auf Anhieb! Allerdings ließ die Leuchtstärke doch noch zu wünschen übrig. Mehr zufällig stellte ich fest, dass die LED extrem heller wurde, wenn ich ein Spannungsmessgerät parallel zur LED schaltete!??? Tatsächlich waren es nur die Messschnüre, bzw. deren Kapazität, die den Effekt bewirkten. Mit einem Oszilloskop konnte ich dann feststellen, dass in dem Moment die Frequenz stark anstieg. Hm, also habe ich den 100nF-Kondensator gegen einen 4.7nF Typ ausgetauscht und schon war die Helligkeit wie gewünscht. Anschließend habe ich dann nur noch durch Ausprobieren die beste Spule aus meiner Sammlung gesucht... Das beste Ergebnis hatte ich mit einem alten Sperrkreis für den 19KHz Pilotton (UKW), aus dem ich die Kreiskapazität entfernt habe. Und hier ist sie nun, die Mini-Taschenlampe:
Sources:
http://pro-radio.ru/
http://radiokot.ru/
Loading...