With the onset of evening, the lights along the city streets light up on their own; the automation of this process no longer surprises anyone. Today, photo sensors that control street lighting are available not only to public utilities, but also to ordinary owners of country houses. You can make your home more comfortable and smart without any special financial costs or electrical installation skills; you just need to take into account several important nuances: know the photo relay connection diagram and the rules for working with it.
How does the light sensor work?
The task of the photo relay is to turn on the lighting device when it becomes twilight in the yard and turn it off at dawn. The device is based on a photosensitive element (photodiode, gas discharger, photothyristor, photoresistor), which changes its characteristics in light. For example, in a photoresistor the resistance decreases, current easily passes through this element and closes a contact that turns off the lighting.
Several lighting devices can be connected to one sensor
Additional elements of the device help to avoid erroneous switching on/off, adjust the sensitivity of the sensor, strengthen the signal from the sensor, etc.
Why do you need a photo relay?
Light accents around the house are not only convenient, but also beautiful
The street lighting system can operate without photosensors. But the day-night sensor gives it additional advantages:
- Convenience. A standard lighting system involves installing a switch near the front door on the street, or in the house itself. This is convenient for those who decide to leave the house late in the evening. But when returning home in the dark, you have to go to the switch with a flashlight, or even open the lock in complete darkness. With the sensor, you can set the backlight to turn on at dusk and the owner will arrive at an already illuminated area at the gate or in front of the garage.
- Energy Saving. Residents of country houses often forget to turn off the lights outside before going to bed or leaving home. This will not happen with a sensor. The standard one will turn off the light with the first rays of the sun, combined with a motion sensor - as soon as everyone leaves the yard, and the programmable one - at exactly the specified time.
- Presence simulation. Thieves do not risk sneaking into a house while the owners are home, and the main sign of their presence is the light being on. Street lighting with a sensor creates the appearance of presence and thus protects the house from vandals and robbers while the family is on vacation or on a business trip.
Light sensors have proven themselves well in urban lighting systems; they are often used by public utilities, owners of shopping centers, parking lots, billboards, etc. In private country houses, photo relays are also beneficial and appropriate, and therefore are becoming increasingly popular.
Selecting a photosensor model taking into account technical characteristics
Technical characteristics are often indicated directly on the photo relay body
When purchasing, pay attention to:
- Voltage (volts). Manufacturers produce devices powered by mains voltages of 12V, 24V and 220V. We recommend choosing the latter, as they can be connected to a household network. For other devices, you will have to purchase voltage converters, which will make the designs more expensive and less reliable.
- Switching current (amps). If this setting is not selected correctly, the life of the sensor will be significantly reduced. Therefore, the number of lighting devices connected to the photo relay and the type of lamps used (diode, housekeeper, incandescent) need to be determined before choosing a sensor. To obtain the maximum switching current, you need to divide the sum of the powers of all lamps by 220 (mains voltage). The figure indicated in the device passport must be greater than that obtained as a result of calculations.
- Switching threshold (lumens). The parameter determines the sensitivity of the sensor to light. If the sensor is insensitive, the lighting will start to turn on too early, and if the sensor is too sensitive, it will prevent it from turning on in winter due to the reflection of light from the snow. Look in the passport at the threshold adjustment parameters; the range should be 2–100 Lux or 5–100 Lux.
- On/off delay (seconds). The adjustment range is also indicated in the device passport. It should be possible to set a delay of 5-7 seconds so that the lights don't turn off every time a car drives by.
- Power (watts). The lower this indicator, the more economical the device will be. The device passport indicates power consumption in the active phase (up to 5 W) and in standby mode (up to 1 W).
- Degree of protection. Since street lighting sensors are mounted outdoors, drops and moisture vapor should not penetrate into the housing, it should not be deformed due to ultraviolet radiation, etc. The weather resistance of the device must be IP44. If the sensor is placed in a protective box or under a canopy, the figure may decrease. If you select a model with an external photo relay, the degree of protection can be reduced only for the photo sensor, but not for the main unit.
If your region has very harsh winters, pay attention to the operating temperature range, and if there is little space on the facade, give preference to compact models.
Types of light sensors
Conventional inexpensive light sensors allow you to automate lighting and adjust it to the length of daylight hours. But since in this case the light burns all night, manufacturers began to create models with greater capabilities.
Example of a photo relay with a motion sensor
Among them:
- . They turn on the lights when something starts to move in the controlled area. Thanks to the photo sensor, the switch-on signal is triggered only during the dark period. The device is inexpensive, reliable and compact. But if there are pets running around the area, or there are plant branches in the field of view of the sensor, there is a high probability of a false sensor response.
- Photo relay equipped with both a motion sensor and a timer. The device can be finely tuned so that it only works when needed. For example, from 20.00 to 22.00 when a guest approaches the gate or the owner returns.
- Photo relay with timer. The device makes it possible to save energy by turning off the lights when not in use. If the family’s habits are established and tied to a certain time, this option can be very convenient. Many people prefer this type of device, since they do not have to be installed outside; the timer can give a signal to turn on directly from the house.
- Programmable photo relays. Devices of this type are the most expensive, but superior to other types in functionality. They make it possible to set the lighting on/off depending on natural illumination, time period, day of the week, and season.
The optimal price and functionality are day-night devices with a motion sensor and built-in timers. For the vast majority of everyday tasks, the scenarios they implement are quite sufficient.
Another approach to classifying photosensors is the type of design. There are:
If you have little experience in installing electrical appliances, or you are afraid of damaging the new wallpaper, it is better to prefer an externally mounted photo relay.
Photo relay manufacturers: countries and prices
The production of such devices does not require unique equipment or complex technological processes, therefore, along with Western products, the market offers many domestic photo sensors. Moreover, each country has both budget and inexpensive models with varying degrees of protection.
Comparison table of photo relays from different manufacturers
| Name | Switching current, A | Operating voltage in the network, V | Degree of protection, IP | Manufacturer | price, rub. |
|---|---|---|---|---|---|
| FR-6 | 10 | 240 | 54 | Ukraine | 150 |
| PS-1 | 6 | 220 | 44 | Uzbekistan | 200 |
| HOROZ HL 472 | 25 | 230 | 44 | Türkiye | 210 |
| FERON SEN 27 | 25 | 220 | 54 | China | 250 |
| FR-601 | 5 | 230 | 44 | Russia | 420 |
| SOU-1 | 16 | 230 | 56 | Czech | 650 |
| Lux-2 | 8 | 230 | 44 | Russia | 800 |
| Luna 126 Star Theben | 16 | 230 | 55 | Germany | 2500 |
If you find a model with a suitable switching current, degree of protection and other parameters among products from Russian manufacturers, you should not overpay for the German analogue. But you shouldn’t save too much, as this will affect the durability of the sensor.
Photo relay IEK
Photo relays from the Russian manufacturer IEK are very popular in our country.
The IEK FR 601 and FR 602 photo relays look the same, pay attention to the markings
Table of characteristics of IEK photo sensors
| Options | FR-600 | FR-601 | FR-602 |
|---|---|---|---|
| Maximum load when used with incandescent lamps, W | 1300 | 1100 | 2500 |
| Maximum load when used with fluorescent lamps, W | 780 | 600 | 1500 |
| On-state power, W | 0,45–6,6 | 0,45–6,6 | 0,45–6,6 |
| Maximum load current, A | 3–6 | 10 | 20 |
| Operating illumination level, Lux | 5–15 (without adjustment) | 5–50 | 5–50 |
| Deferment period, s | - | 16 | 16 |
| Protection level according to GOST 14254 | IP44 | IP44 | IP44 |
| Degree of protection against electric shock | - | II | II |
| Operating temperature range, o C | -25 … +40 | -25 … +40 | -25 … +40 |
All models of sensors of this brand are made of non-flammable plastic (polycarbonate), which protects the house from accidental fire. According to their technical characteristics, the devices are suitable for Europe and central Russia, with the exception of very hot regions and the Far North.
Choosing a location for installation
The photosensor is located outside the flashlight illumination area
If the sensor is placed incorrectly, the entire system will not function properly. Therefore, the location of the photosensor should be located:
- away from high fences, trees, awnings and other obstacles to natural light;
- in an area illuminated only by sunlight and not by lanterns;
- far from combustible and flammable materials (in case of a short circuit);
- in areas that are not exposed to chemical influences and mechanical shocks.
It is also advisable that the sensor is not too high, then it can be wiped from dust from time to time without using a ladder.
Schemes for connecting a photo relay to a lantern
To install the day-night sensor, no specialized knowledge is required, and tips are printed either on the packaging or on the device itself. Depending on the model, two or three wires come out of the photosensor housing.
Connection diagram for photo relay with grounding
Three wires come out of the universal device:
- phase (red, marked L);
- zero (blue, marked N);
- grounding (green, PE marking).
Stand for demonstrating the correct connection of a photo relay
The photo example shows that two cables should enter the device, each of them with three colored wires. Cable 1 is designed to connect to the light bulb. Its blue terminal is connected to the N terminal, and the red one to the L terminal, in the same way they are connected to the light bulb socket. The ground wire is connected to the green wire of cable 2 and secured with a screw. Cable 2 is necessary to power the device; its red and blue wires are connected in the same way, to the adjacent terminals N and L.
Connection diagram for photo relay without ground wire
There are models with two terminals, there is no ground wire. Such photo sensors are suitable for houses where the grounding system is equipped separately.
Their connection method is even simpler: the incoming cable is connected to terminals L and N (phase and zero, respectively), and only the phase cable is connected for the output. Zero is supplied to the lamp through the KM starter, past the photosensor.
If the photosensor must control several light bulbs, you need to add a controller to it.
Connection diagram for a photo sensor for three bulbs
The controller connects to the output terminals of the photosensor and adds another contact pair. With its help, lamps can be connected in parallel rather than in series (as in a Christmas tree garland). Connecting several consumers through the controller makes the circuit more reliable and allows the lamps to light even when one of them fails.
Video instructions for connecting and setting up a photo relay
DIY making
Having minimal skills in using a soldering iron, you can assemble a simple relay yourself. To begin with, you should use a circuit with a minimum of components.
Even a beginner can assemble such a photo relay
You will need:
- PR1 - photoresistor;
- R1 - 10K electrolytic capacitor;
- VD1 KD522 - protective thermoelectric diode;
- VT1 and VT2 - n-p-n structure transistors;
- KT315B - transistor;
- K1 - 10,000 microfarad electrolytic capacitor;
- K1.1 - on/off switch;
- neutral and phase wires.
These parts can be bought at a radio store, or soldered from old unnecessary equipment.
In this circuit, transistors VT1 and VT2 form an emitter follower, thanks to which the signal from the photosensor is amplified and is powerful enough to open the electrical circuit. Thanks to the diode VD1, reverse current flow is prevented. And the relay completely replaces the transistor cascade used in more complex circuits.
Self-assembled photo relay
To assemble the photosensor, you need to solder the legs of the elements used in series, or use a board with contacts. To make sure the product is working, it is advisable to test it on a stand with one lamp. In order to set the appropriate sensitivity of the device, it is necessary to solder a variable resistor into the circuit. Change the resistance of the resistor until the device begins to give an on/off signal at the correct level of illumination (experiments can be carried out in the evening with the lamps turned off). As soon as the desired resistance level is found, instead of an adjustable resistor, you need to solder a constant one. As a housing for the product, you can use a distribution box for external installation of electrical wiring, only you need to make a window in it for the photoresistor.
Since the relay allows the circuit to be used on a 220V network, it can be connected in the same way as a purchased one.
Video instructions for making a photosensor for LED lighting
Settings
If you bought a photo sensor ready-made, you will need to adjust its parameters so that the light does not turn on too early and does not burn when it is already light outside.
Photo relay sensitivity setting
Looking under the photosensor cover, it is easy to notice a round knob, by turning which the light sensitivity of the device is set. To begin, set it to the extreme right position (indicated by a minus sign). This means that it will take pitch darkness to turn on the lights. Connect the sensor to the network and at the time when you would like to turn on the street lighting, open the case and turn the lever until the sensor gives a signal to turn on. Leave the lever in the same position and the system will always start at the same light level.
Since the light reflected from the snow can lead to the light turning off too quickly in the winter, the light sensitivity of the sensor should be reduced and increased again in the spring according to the described scheme.
Adjusting photo relay with remote sensor
In more complex photo relays with remote sensors, the on/off delay time is also adjusted. To change, you also need to switch the corresponding lever, only it does not turn smoothly, but from one position to another. The positions and levers are marked directly on the body, so there will be no problems with setup.
Possible malfunctions of the street lighting mechanism
If the photo sensor does not work correctly, the reason most often lies in installation or configuration errors.
First, make sure that there is no street light or high fence in front of the day-night device, maybe the tree has become much taller since installation, or has begun to shade the area more when leaves appear on it. Such obstacles must be removed or the photo relay moved to a more suitable location.
It is also possible that one of the residents of the house accidentally changed the settings, or they became irrelevant with the change of season. Monitor the set light sensitivity and set the response delay to at least 5 minutes.
Often a photo relay malfunction is determined visually
When simple methods do not help, you need to look inside the device. Perhaps moisture got into the case and the contacts oxidized, or as a result of a power surge in the network, one of the board elements burned out. If the damage is not too significant, you should take the device to a workshop and consult about repairs. But if the board is noticeably damaged, you will have to replace the device completely (or just the remote sensor). In a self-made device, you should first check the quality of soldering, and if necessary, replace the failed element.
When the device is fully operational and correctly configured, the reason may lie in the wires connected to it. Carefully check the integrity of the insulation in each section and, if necessary, replace the damaged cable.
If you cannot detect the fault yourself, you must contact the seller (if the device is under warranty) or a manufacturer’s representative.
Is it worth using a photo relay on your site?
It is very inconvenient to regulate street lighting with so many points without a photo relay
Table of advantages and disadvantages of day-night sensors
Pros of photo relay | Cons of photo relay |
|---|---|
| Ease of use of street lighting | If installed incorrectly, the light may turn on/off randomly |
| Saves energy | For significant savings, you need a device with a motion sensor/timer and energy-saving lamps |
| Operates 10 times faster than a mechanical switch | In practice, you still have to set a delay start |
| Increases the service life of lamps in luminaires | The effect will be noticeable only if, before installing the sensor, the lighting was turned on/off at least 5 times per evening |
| The device is compatible with all types of lamps | For proper operation, it is necessary to carefully select a device with a power reserve |
People who have already decided to install a photo relay on their site will never give up this device. After all, you only need to configure and connect it once, and throughout its service life, the day-night sensor regularly turns on the light when and where it is convenient for the owner.
To control the operation of many electrical devices, special controllers are required, which are responsible for the accuracy and correctness of their operation. We propose to consider how to connect a simple street photo relay, what it is and its operating principle.
Description of photo relay
Sensitive photo relay based on a triac GOST 51324.2.1-99. is an optocoupler device consisting of LEDs optically connected to the contacts of electrical appliances. It is also often called a twilight LED sensor, a day-night device, etc.
Photo – Photo relay photoPhoto relays are offered various advantages Compared to mechanical time relays:
- Small size. Housed in small units such as USOP, the fixture is designed with a reduced board;
- Long service life. In the absence of mechanical contact, the shelf life is significantly extended due to the fact that wear is completely absent;
- Low current drive. This device can operate with an incoming current of even a few milliamps without an amplifier. Thus, neighboring devices can do without drivers;
- Quiet operation. In the absence of mechanical contact, the contactless relay does not make any sounds during operation;
- High speed. Photo relays are about 10 times faster than their mechanical counterparts (which take a few milliseconds to switch).
- Excellent performance, many appliances come with a timer.
The components of the device are: three contact wires for connecting to a common network, a magnetic starter, and an armature.
Photo – Photo relay disassembled Video: simple photo relay
Operating principle
The diagram shows the principle of operation of the device. Photoresistor PR1 reduces its resistance to several Kohms as the illumination increases, due to which phototransistor VT2 opens, which turns on photorelay K1, and this device, in turn, will begin to transmit signals. Diode VD1 protects the circuit from self-induction. Thanks to this principle, even very weak signals can turn the light on or off.
Photo – Photo relay circuit The main working part is a photocell, which is a gas tube in which gas ionization occurs. It has a cathode that is capable of producing electrons in proportion to the intensity of light directed towards it, and the tube is also equipped with an anode to collect electrons.
Photo – Photo relay Whenever a negatively charged surface is placed in an atmosphere of an ionizable gas, such as mercury vapor or any inert gas, electrons are transferred to it. There, by using the Fermi-Dirac velocity theory, electrons are accelerated depending on the strength of the applied electric field.
Photo – Photo relay TDM These electrons travel a relatively short distance before colliding with an ionizing gas atom. When an electron, which has constant kinetic energy, passes through an ionizing substance, it disturbs the atoms it encounters. Also, its trajectory of action may change periodically. If the material is gaseous, the resulting fragments or ions may move away from each other. But if electrons are knocked out of atoms, then they move in one direction, and the residual positive ions move in the opposite direction. The output of the ionization type or photocell depends on the number of electrons at the anode.
It is the movement of electrical particles in a certain sequence that causes the device to switch. It must be said that this is especially convenient for devices with a motion sensor Finder, Legrand.
Application and connection
Electronic devices with a built-in photosensor of light are used to organize and control automatic street lighting, external façade, driveway or household lighting. Often combined with it, console lamps of the housing and communal services type are used, which are equipped with protective glass and a special grille.
The device operates on a very small microcircuit and transistors, and instructions are often given on the case on how to properly connect the device. We use a light control switch to demonstrate step by step how to install the fixture. Despite its externally small size, this device does an excellent job of lighting courtyards, parks and gardens.
Photo – photo relay FR-3 In general, photo relays for street lighting are recommended to be installed in the middle position. To install the switch yourself, you need to use a special bracket that is attached to the wall. The canopy is installed directly into the photo relay using a screw. The installation location depends on the lighting; try to choose an area where nothing prevents the sun's rays from hitting the working surface of the device, otherwise interference will begin on the photodiode and the device will not work correctly. Depending on the characteristics of the device, the presence of trees, furniture, curtains, etc. in front of the photo relay is not allowed.
The diagram of the photo relay and its principle of connection to the network is most often depicted on the box of the device, it is very convenient, you do not need to look for one that is suitable specifically for your device. Detailed instructions How to connect a photo relay with your own hands:
- There are three wires coming out of the relay: brown, blue and red. Based on the standard parameters and indicators, brown is a phase cable, red is an extension wire, it goes like switching to a lamp, blue is zero (if you are developing a homemade relay, then you need to take these branches into account);
- In order for everything to be connected correctly, it is necessary to connect the wires to the console lamp as a load, this is demonstrated by the circuit designation.
To check that the connection is correct, you need to plug in the starter and see if the spotlight or flashlight works.
Photo - Connecting a photo relay Relay installation and grounding
If a TN-S or TN-C-S type grounding system is used in an apartment, house or street, the electrical circuit is powered from the network by a three-wire cable (phase wire, neutral, ground). But for connecting lamps with TN-C type wiring, the connection will differ only in that there is no PE conductor.
The adjustment is made according to the manufacturer's settings. Before connecting the lamp, be sure to check the passport, certificate and patent of the seller, so that later you do not have to make major repairs to the wiring in the apartment. It is advisable to install a separate machine for this controller in the distribution board (cabinet).
You can buy a photo relay at any electrical store; the price directly depends on the brand and area of operation (street - FR-601 IEK, FR-602, facades - FRSU-1-0 uhl 4.2, FRSU-2-0 and other types). The most popular models are FR-1 12 volt, UTFR-1M, CSM, LUNA 110 AL, TWS-1, TWS-1M, AWZ-30, ABB (ABB), LXP-01, DLS-1/50, AZH-S , AS-7, RFS-11, FB-2-16A (range 2-4 kW), LUX 2.
Photo – Connecting photo relay FR-601 The creation of a sensor responsive to light was described and examples of control circuits for a low-power electric motor and LED were given. It would be more useful to control some powerful load, for example: an incandescent lamp, a powerful electric motor, etc. A simple photo relay circuit for a powerful load is shown in Figure 1:
Figure 1 - Photo relay triggered when illumination decreases
without sensitivity adjustment
This circuit uses an electromagnetic contact relay. The simplest, cheapest and most accessible way to control a powerful load is to use an electromagnetic contact relay:
The relay shown in the photo above was removed from a broken imported refrigerator; this relay can switch (connect and disconnect in this case) a load consuming a current of no more than 16A. 16A is quite enough for many household electrical appliances. On the body of this relay it is written that 12 V is required for the DC coil, but in practice, 9 V from the power supply for the modem with a rectifier was enough to operate this relay:
If 9V is not enough, you can power the circuit from 12V. If you replace resistor R1 with a variable or trimmer, you can adjust the sensitivity to light.
The reverse current of this photodiode is amplified by transistor VT1:
This transistor forms a voltage divider together with resistor R1:
As mentioned above, this resistor can be replaced with a variable or trimmer so that the sensitivity of the circuit can be adjusted.
Transistor VT2 directly controls the relay coil:
KT973 is well suited for this purpose. The relay is connected to the collector of this transistor.
To prevent transistor VT2 from burning out when it is suddenly closed, a reverse diode is placed parallel to the relay coil:
This diode can be replaced with any other suitable diode.
Resistor R2 is not required, but it can be installed to limit the current or reduce its consumption.
The power part of the circuit requires connectors and wires:
The relay can connect the load to a 220V network. Do not forget that the mains voltage is dangerous and when working with it you must take precautions to avoid electric shock.
After preparing all the necessary parts, you can begin assembling the relay.
It is better to solder the reverse diode directly to the relay.
A load with a power source (not necessarily a 220V network) can be connected to the assembled relay. Using this photo relay paired with an infrared radiation source, you can make a presence sensor:
Figure 2 - Scheme turning on the load with increasing lighting
If a photo relay turns on an incandescent lamp when the illumination decreases, then it is necessary to somehow close the photodiode from the light of the incandescent lamp, otherwise, when the illumination decreases, the relay will begin to turn on and off frequently, which will lead to its rapid wear and failure. If an infrared photodiode is used, then the photo relay will not respond to the light of a fluorescent lamp (if it is not brought close enough) or an LED lamp (if it does not have infrared LEDs with the corresponding wavelength of emitted light). It is better not to test the IR control panel on this photo relay:
Photosensors built into certain electronic devices can be used to effectively control light output. This article will discuss a do-it-yourself photo relay: circuits, design and application.
Purpose
This device is designed to turn on the lighting when it gets dark and turn it off when dawn comes. When assembling with your own hands, the photo relay circuit must include a phototransistor or photoresistor, which change their parameters with the dynamics of illumination. The power circuit is open as long as the required amount of light reaches these devices. As soon as darkness sets in (its parameters can be set), the circuit closes. When morning comes, the process goes in the opposite direction.
Specifications
The do-it-yourself photo relay circuit should indicate which light sensor will be used: built-in or remote. The latter is characterized by small dimensions, can be protected from illumination and located in the shield. Photo relays equipped with a built-in sensor are located near the lamp. In this case, light should not affect the photocell. This option is acceptable for solar-powered lamps.
Exploitation
The photo relay circuit with your own hands or 12 V (voltage) provides that it depends on the latter from which the power is supplied. The creation of this device should provide for its operation in various extreme conditions of the region of residence.
The housing protection must be at least IP23 for home and IP44 for outdoors. The last protection class shows that splashes of water, as well as solid particles larger than 1 mm in size, will not enter the housing.
These technical characteristics are relevant for industrial designs. It is quite difficult to ensure that a photo relay assembled according to the circuit diagram with your own hands has the same characteristics. The maximum load power should be 20% greater than the total load from those devices that are connected.
FR models
Before we consider the photo relay circuits with our own hands, let’s focus on the most popular industrial models - FR-601 and FR-602.
They are as simple as possible for connection even by an untrained user and differ only in the maximum possible cross-section of the connected conductors, which also determines the differences in the rated load current (10 and 20 A, respectively). The photocell of these models is built-in and is adjustable from 0 to 50 lux.
You can repeat such devices at home on your own. This is most relevant if it is necessary to connect a large number of lighting devices. The diagram of a photo relay with your own hands is shown in the figure.
To make it you will need:
relay SHA-24VDC-S-A (Rel1);
photocell (PH, up to 100 kOhm);
bipolar transistors BC857A (2 pcs. Q1 and Q2 or domestic KT3107B instead of the latter);
resistors (R2, R4-R9: 1.5; 1 MOhm, 560, 200, 100, 75 and 33 kOhm; power 0.125 W) and R3, 220 Ohm, 2 W;
trimming resistor (WL, 2.2 mOhm);
rectifier diodes 1N4007 - 5 pcs. and one 1N4148 1N4749 zener diode or three D814A or two D814D connected in series;
capacitor (C2, 0.7 µF 400 V);
electrolytic capacitors (C4-C5, 100 µF 50 V and 47 µF 25 V).
The disadvantages of self-assembled FR can be described as follows. From a technical point of view, this photo relay is no different from the factory assembly. The main differences will be that for photo relays using a circuit for street lighting with your own hands, it is very difficult to achieve the IP44 protection standard, which the industrial design corresponds to. Also, the latter has a larger operating temperature range. A homemade photo relay may stop working in cold weather if even one connection is made poorly.
High power devices
These include the FR-7 model. It has no protection against moisture, the power consumption is quite high, the contact clamps are open, and the trimmer located on the front panel is not protected. However, this device can operate in networks with a voltage of 220 V. A specialist can set the adjustment to 10 lux, since it is very difficult to achieve this on your own.
Security alarm photorelay with self-locking
It can be used as a light detector. If light does not reach the photoresistor PR1, the LED HL1 lights up. This helps to control the security zones of any building or summer cottage. As long as PR1 is illuminated, it has a small resistance to the current, which is constant, and the voltage drop does not cause the thyristor VS1 to turn on. When the flow of light going to the photosensor is interrupted, the resistance of the photoresistor increases to 1-5 MOhm, in this case, capacitor C1 will receive energy from the power source, which helps unlock VS1 and, as a result, turn on the LED.
Thus, in the do-it-yourself photo relay circuit, switching on when it is dark is provided. The device is returned to its original state using the S1 button. Instead of the above LED and limiting resistor R2, you can use analogues - low-power EM relays with an operating current of 15-30 mA.
A substitute for the brand of thyristor under consideration can be similar devices of the KU101 series. Photo relay PR1 includes two parallel-connected photoresistors SFZ-1. Models of capacitors used: C1 type MBM or other similar ones. Any LEDs and button S1 can be used. Fixed resistors are used type MLT-0/25.
Photo relay with universal timer
This device is automatic and can be used in any populated areas, as well as in private plots. Contact with a photoresistor or two SFZ-1 devices connected in parallel for better sensitivity of even weak natural light closes transistor VT1. As the illumination of their working surface decreases, the resistance between the transistor emitter and the base reaches values exceeding 100 kOhm.
The transistor opens when there is low resistance between the positive terminal of the power source and the base of VT1. Relay K1 is activated, which helps connect the thyristor anode output to the pole with a positive charge in the power source. Next, the DA1 KR1006VI1 timer is connected with the output voltage set to 10.5 V. It is possible to connect low-power relays to the DA1 output without using a key transistor stage.
Relay K1 is activated, due to which the lighting lamp HL1 is kept on. Analogues of the thyristor are KU101A-KU101G, KU221, regardless of the letter. Analogues of transistor VT1 are KT312A, B, V and others in terms of electrical characteristics. At the same time, its current gain h21e should not be less than 40. The relay operating current is 15-30 mA at a voltage of 12 V, that is, it should be low-power.
Types of permanent resistors MLT-0.125. Types of capacitors S1 KM, S2-K50-20. In this case, the operating voltage must exceed 16 V. Using diodes VD1, VD2, the junction of the transistor VT1 and the output of the DA1 microcircuit are protected from sudden fluctuations in alternating current, which prevents bouncing of the relay contacts K1 and K2 when they are activated. The first ones can be replaced with others included in the KD522 series.
The last two circuits do not require a special supply voltage; they can work with low-power relays, transformerless and transformer stabilizers with an output voltage of 10-16 V.
Finally
As can be seen from this article, there are various DIY projects. They can operate with a voltage of 12 V, as well as 220 V. You can create devices yourself that are not inferior in technical characteristics to the quality of industrial designs. The most difficult thing is to achieve the same level of protection.
Yes, sometimes it is much easier to buy a light sensor in a store. But, if you need, for example, 20 of these sensors. I would argue about the profitability of such a purchase.
I am posting, in my opinion, a simple and easily repeatable photo relay circuit from those that are produced in mass production.
The tuning resistor WL adjusts the relay response threshold at illumination levels from 5 to 50 lux.
ZD1 - 24 Volt zener diode.
PH photoresistor, any with a difference of about 10 - 70 kOhm will do.
A jar of cream or any other container with a floor or transparent walls is perfect as a body.
Zero and phase do not matter when connecting. It depends on them whether there will be voltage on the lamp base when the relay is off or not.
In Fig. 1 above shows a typical lamp or load connection diagram. In Fig. 2 an option with a switch is proposed. Since sometimes when the relay is turned off, you need to force the lamp to turn on.
Photo relay board, top view.
Drawing of a transparent printed circuit board. View from above. The black stripes are "windows". Needed to prevent short circuits and sparking between conductors. They are not required, but recommended.
The board is wired for 2 types of relays. But, it can be easily redrawn to match the relays you have.
In the photo of the bottom side of the board, these “windows” are clearly visible.
List of radioelements
| Designation | Type | Denomination | Quantity | Note | Shop | My notepad |
|---|---|---|---|---|---|---|
| Q1-Q2 | Bipolar transistor | BC857A | 2 | To notepad | ||
| D1-D5 | Rectifier diode | 1N4007 | 5 | To notepad | ||
| VD1 | Rectifier diode | 1N4148 | 1 | To notepad | ||
| ZD1 | Zener diode | 1N4749 | 1 | To notepad | ||
| R2 | Resistor | 1 MOhm | 1 | 0.125 W | To notepad | |
| R3 | Resistor | 220 Ohm | 1 | 2 W | To notepad | |
| R4 | Resistor | 560 kOhm | 1 | 0.125 W | To notepad | |
| R5 | Resistor | 1.5 MOhm | 1 | 0.125 W | To notepad | |
| R6 | Resistor | 75 kOhm | 1 | 0.125 W | To notepad | |
| R7 | Resistor | 33 kOhm | 1 | 0.125 W | To notepad | |
| R8 | Resistor | 100 kOhm | 1 | 0.125 W | To notepad | |
| R9 | Resistor | 200 kOhm | 1 | 0.125 W | To notepad | |
| PH | Photoresistor | 0-100 kOhm | 1 | To notepad | ||
| W.L. | Trimmer resistor | 2.2 MOhm | 1 | To notepad | ||
| C2 | Capacitor | 0.68uF 400V | 1 |
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