A fluorescent lamp (LL) is a glass tube filled with an inert gas (Ar, Ne, Kr) with the addition of a small amount of mercury. At the ends of the tube there are metal electrodes for applying voltage, the electric field of which leads to gas breakdown, the occurrence of a glow discharge and the appearance of electric current in the circuit. The glow of the gas discharge is pale blue and very weak in the visible light range.
But as a result of an electrical discharge, most of the energy passes into the invisible, ultraviolet range, the quanta of which, entering phosphorus-containing compounds (phosphor coatings), cause a glow in the visible region of the spectrum. By changing the chemical composition of the phosphor, different glow colors are obtained: for fluorescent lamps (FLLs) various shades of white have been developed, and for decorative lighting you can choose lamps of a different color. The invention and mass production of fluorescent lamps is a step forward compared to low-efficiency incandescent lamps.
What is ballast used for?
The current in a gas discharge grows like an avalanche, which leads to a sharp drop in resistance. To ensure that the electrodes of the fluorescent lamp do not fail due to overheating, an additional load is connected in series, limiting the amount of current, the so-called ballast. Sometimes the term throttle is used to refer to it.
Two types of ballasts are used: electromagnetic and electronic. The electromagnetic ballast has a classic transformer configuration: copper wire, metal plates. Electronic ballasts use electronic components: diodes, dinistors, transistors, microcircuits.
For the initial ignition (start) of the discharge in the lamp in electromagnetic devices, a starting device is additionally used - a starter. In the electronic version of the ballast, this function is implemented within a single electrical circuit. The device turns out to be light, compact and is united by a single term - electronic ballast (EPG). The widespread use of electronic ballasts for fluorescent lamps is due to the following advantages:
- these devices are compact and light in weight;
- the lamps turn on quickly, but smoothly;
- absence of flicker and noise from vibration, since electronic ballasts operate at high frequencies (tens of kHz) in contrast to electromagnetic ones operating from mains voltage with a frequency of 50 Hz;
- reduction of heat losses;
- electronic ballast for fluorescent lamps has a power factor of up to 0.95;
- the presence of several, proven types of protection that increase safety of use and extend service life.
Circuits of electronic ballasts for fluorescent lamps
Electronic ballasts are an electronic board filled with electronic components. The circuit diagram of the connection (Fig. 1) and one of the options for the ballast circuit (Fig. 2) are shown in the figures.
Fluorescent lamp, C1 and C2 – capacitors 
Electronic ballasts can have different circuit designs depending on the components used. The voltage is rectified by diodes VD4–VD7 and then filtered by capacitor C1. After voltage is applied, capacitor C4 begins charging. At a level of 30 V, dinistor CD1 breaks through and transistor T2 opens, then the self-oscillator on transistors T1, T2 and transformer TR1 is switched on. The resonant frequency of the series circuit of capacitors C2, C3, inductor L1 and generator are close in value (45–50 kHz). The resonance mode is necessary for stable operation of the circuit. When the voltage on capacitor C3 reaches the starting value, the lamp lights up. At the same time, the regulating frequency of the generator and voltage are reduced, and the inductor limits the current.
Electronic ballast repair
If it is not possible to quickly replace a failed electronic ballast, you can try to repair the ballast yourself. To do this, select the following sequence of actions to troubleshoot:
- First, check the integrity of the fuse. This breakdown often occurs due to overload (overvoltage) in a 220 volt network;
- Next, a visual inspection of electronic components is carried out: diodes, resistors, transistors, capacitors, transformers, chokes;
- If characteristic blackening of a part or board is detected, repairs are made by replacing it with a serviceable element. How to check a faulty diode or transistor with your own hands, having a regular multimeter, is well known to any user with a technical education;
- It may turn out that the cost of replacement parts will be higher or comparable to the cost of a new electronic ballast. In this case, it is better not to waste time on repairs, but to choose a replacement that is similar in parameters.
Electronic ballasts for compact LDS
Relatively recently, fluorescent energy-saving lamps, adapted for standard sockets for simple incandescent lamps - E27, E14, E40, have become widely used in everyday life. In these devices, the electronic ballasts are located inside the socket, so repairing these electronic ballasts is theoretically possible, but in practice it is easier to buy a new lamp.
The photo shows an example of such an OSRAM lamp with a power of 21 watts. It should be noted that at present, the position of this innovative technology is gradually being occupied by similar lamps with LED sources. Semiconductor technology, constantly improving, makes it possible to quickly achieve prices for LDS, the cost of which remains practically unchanged.
T8 fluorescent lamps
T8 lamps have a glass bulb diameter of 26 mm. The widely used T10 and T12 lamps have diameters of 31.7 and 38 mm respectively. LDS with a power of 18 W are usually used for lamps. T8 lamps do not lose their functionality during supply voltage surges, but if the voltage drops by more than 10%, lamp ignition is not guaranteed. Ambient temperature also affects the reliability of the T8 LDS. At sub-zero temperatures, the luminous flux decreases and failures in lamp ignition may occur. T8 lamps have a lifespan of 9,000 to 12,000 hours.
How to make a lamp with your own hands?
You can make a simple lamp from two lamps as follows:
- select 36 W lamps that are suitable for color temperature (shade of white);
- We make the body from a material that will not ignite. You can use the housing from an old lamp. We select electronic ballasts for a given power. The marking should indicate 2 x 36;
- We select 4 sockets marked G13 for the lamps (the gap between the electrodes is 13 mm), a mounting wire and self-tapping screws;
- cartridges must be secured to the body;
- The installation location of the electronic ballasts is chosen to minimize heating from operating lamps;
- the cartridges are connected to the LDS sockets;
- to protect lamps from mechanical stress, it is advisable to install a transparent or matte protective cap;
- The lamp is fixed to the ceiling and connected to a 220 V power supply.
Ballast for a gas-discharge lamp (fluorescent light sources) is used to ensure normal operating conditions. Another name is ballast (ballast). There are two options: electromagnetic and electronic. The first of them has a number of disadvantages, for example, noise, the flickering effect of a fluorescent lamp.
The second type of ballast eliminates many of the disadvantages in the operation of the light source of this group, and therefore is more popular. But breakdowns in such devices also happen. Before discarding, it is recommended to check the ballast circuit elements for faults. It is quite possible to carry out electronic ballast repairs yourself.
Types and principle of operation
The main function of electronic ballasts is to convert alternating current into direct current. In another way, electronic ballast for gas-discharge lamps is also called a high-frequency inverter. One of the advantages of such devices is their compactness and, accordingly, low weight, which further simplifies the operation of fluorescent light sources. And the electronic ballast does not create noise during operation.
An electronic ballast, after connecting to a power source, provides current rectification and heating of the electrodes. In order for the fluorescent lamp to light up, a certain voltage is applied. The current is adjusted automatically, which is implemented using a special regulator.
This feature eliminates the possibility of flickering. The last stage is when a high-voltage pulse occurs. The fluorescent lamp is ignited in 1.7 s. If there is a failure when starting the light source, the filament body instantly fails (burns out). Then you can try to make the repair yourself, which requires opening the case. The electronic ballast circuit looks like this:
The main elements of the electronic ballast of a fluorescent lamp: filters; the rectifier itself; converter; throttle. The circuit also provides protection against power supply surges, which eliminates the need for repairs for this reason. And, in addition, the ballast for gas-discharge lamps implements the power factor correction function.
According to their intended purpose, the following types of electronic ballasts are found:
- for linear lamps;
- ballast built into the design of compact fluorescent light sources.
Electronic ballasts for fluorescent lamps are divided into groups that differ in functionality: analog; digital; standard.
Connection diagram, startup
The ballast is connected on one side to the power source, on the other to the lighting element. It is necessary to provide for the possibility of installing and fastening electronic ballasts. The connection is made in accordance with the polarity of the wires. If you plan to install two lamps via ballasts, a parallel connection option is used.
The diagram will look like this:
A group of gas-discharge fluorescent lamps cannot operate normally without a ballast. Its electronic design ensures a soft, but at the same time almost instantaneous start-up of the light source, which further extends its service life.
Ignition and maintenance of the lamp's functioning is carried out in three stages: heating of the electrodes, the appearance of radiation as a result of a high-voltage pulse, maintenance of combustion is carried out by constantly applying a small voltage.
Failure detection and repair work
If there are problems with the operation of gas-discharge lamps (flickering, lack of glow), you can make repairs yourself. But first you need to understand whether the problem is in the ballast or the lighting element. To check the functionality of the electronic ballasts, the linear light bulb is removed from the luminaires, the electrodes are short-circuited, and a regular incandescent lamp is connected. If it lights up, the problem is not with the ballast.
Otherwise, you need to look for the cause of the failure inside the ballast. To determine the malfunction of fluorescent lamps, it is necessary to “ring” all the elements in turn. You should start with the fuse. If one of the circuit components fails, it must be replaced with an analogue. The parameters can be seen on the burnt element. Repairing ballasts for gas-discharge lamps requires the use of soldering iron skills.
If everything is in order with the fuse, then you should check for serviceability of the capacitor and diodes that are installed in close proximity to it. The capacitor voltage should not fall below a certain threshold (this value varies for different elements). If all the ballast elements are in working order, without visible damage, and the ringing also did not give anything, all that remains is to check the inductor winding.
In some cases it is easier to buy a new lamp. This is advisable to do in the case where the cost of individual elements is higher than the expected limit or in the absence of sufficient skills in the soldering process.
Repair of compact fluorescent lamps is carried out according to a similar principle: first, the housing is disassembled; The filaments are checked and the cause of the breakdown on the control gear board is determined. There are often situations when the ballast is fully operational, but the filaments are burned out. Repairing the lamp in this case is difficult. If there is another broken light source of a similar model in the house, but with an intact filament, you can combine the two products into one.
Thus, electronic ballasts represent a group of improved devices that ensure efficient operation of fluorescent lamps. If the light source is flickering or does not turn on at all, checking the ballast and its subsequent repair will extend the life of the light bulb.
Classes with sufficient luminous flux and at the same time economical, prompted, one might even say, some searching and testing of options. At first I used an ordinary small clothespin lamp, changed it to a small tabletop fluorescent lamp, then there was an 18-watt fluorescent lamp of a “ceiling-wall” version made in China. I liked the latter the most, but the mounting of the lamp itself in the fittings was somewhat underestimated, literally by two to three centimeters, but “for complete happiness” they were not enough. I found a way out by doing the same thing, but in my own way. Since the operation of the existing electronic ballast did not cause any complaints, it was logical to repeat the scheme.
Schematic diagram
This is a large part of this electronic ballast; the Chinese did not include the inductor and capacitor here.
Actually, a diagram faithfully copied from a printed circuit board. The rating of the electronic components that made it possible to do this was determined not only “by appearance,” but also using measurements, with preliminary desoldering of the components from the board. In the diagram, the resistor values are indicated in accordance with the color coding. Only with regard to the choke, I allowed myself not to unwind the existing one to determine the number of turns, but measured the resistance of the wound wire (1.5 Ohms with a diameter of 0.4 mm) - it worked.
First assembly on the circuit board. I carefully selected the component values, regardless of size and quantity, and was rewarded - the light bulb lit up the first time. Ferrite ring (10 x 6 x 4.5 mm) from an energy-saving light bulb, its magnetic permeability is unknown, the diameter of the wire of the coils wound on it is 0.3 mm (without insulation). The first start-up is mandatory through a 25 W incandescent light bulb. If it is on and the fluorescent one initially blinks and goes out, increase (gradually) the value of C4, when everything worked and nothing suspicious was found, and removed the incandescent lamp, then reduced its value to the original value.
To some extent, focusing on the printed circuit board of the original source, I drew a signet for the existing suitable case and electronic components.
I etched the scarf and assembled the diagram. I was already looking forward to the moment when I would be satisfied with myself and glad to be. But the circuit assembled on a printed circuit board refused to work. I had to delve into and select resistors and capacitors. At the time of installation of the electronic ballast at the site of operation, C4 had a capacity of 3n5, C5 - 7n5, R4 resistance of 6 Ohms, R5 - 8 Ohms, R7 - 13 Ohms.
The lamp “fit” not only into the design; the lamp, raised all the way up, made it possible to comfortably use the shelf inside the secretary niche. Babay made the “room” feel comfortable.
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