Brightness control: circuit and device. Switches with dimmer control

To adjust the brightness of incandescent lamps, special regulators are used. These devices are also called dimmers. They exist different modifications, and if necessary, you can always find the right model in the store. Basically, they replace a switch in an incandescent lamp. The simplest modification includes one rotary controller with a handle. When adjusting the brightness, the indicator of electricity consumption is additionally changed.

If you recall the old days, the controls for adjusting the brightness were not used. Instead, special rheostats were installed. With their help, it was also possible to regulate fluorescent lamps. In general, they coped well with their duties, but they had one drawback. It is related to electricity consumption. As mentioned earlier, modern regulators spend less electricity if they are not used at full capacity. In the case of rheostats, this rule does not apply. At the minimum power, electricity is consumed in the same way as at the maximum. Surpluses in this case are converted into heat.

The scheme of a conventional regulator

A simple scheme of the brightness regulator involves the use of a linear type potentiometer, as well as pairs of transistors with low power. To suppress high frequency, the system uses capacitors. Cores in devices of this type need only a ferrite type. Directly in front of the terminals is installed a thyristor diode.

How to install the rotary regulator in the lamp?

In order for the table lamp with the brightness regulator to work properly, check the voltage on the semiconductor. You can do this with a conventional tester. Next, inspect the incandescent lamp board. If it is installed in a single-channel type, then everything is quite simple. Output semiconductors are important to attach to the outlets, on which there is a negative polarity. In this case, the maximum resistance should be 3 Ohm. To check the device, you must turn the controller and follow the brightness of the incandescent lamp.

Push the button into the lamp

In order for the brightness regulator of the incandescent lamp to work properly, it is important to carefully read the control board of the device. Next, you need to connect all the pins. If the circuit is multi-channel, then the voltage on it is checked by the tester. Direct connection of contacts is carried out by means of soldering. It is important that during operation do not touch the resistors. Additionally, care must be taken to insulate the wiring. Before switching on the regulator, check the reliability of all connections. After power supply, you must try to change the brightness by pressing the button.

High-voltage brightness controllers

The high-voltage dimmer control, as a rule, can be found in theaters. There incandescent lamps are used rather powerful, and the devices must be able to withstand heavy loads. Triacs for this purpose are high-voltage (with the mark KU202). Transistors are used bipolar, but their usual modifications are also installed.

Diode bridges are soldered near the thyristors and are necessary for rapid signal transmission. Zener diodes can often be found with the marking D814. They cost the store quite expensive, and this should be taken into account. Variable resistors in the system limit voltage can withstand at 60 ohms. At this time, ordinary analogs are fused only with 5 ohms.

Models with precision resistors

The brightness control with resistors of this type is designed for incandescent lamps of medium power. Zener diodes in this case are applied to 12 V. Variable resistors in regulators are quite rare. Low-frequency modifications can be used. Increase the coefficient of conductivity in this case can be due to an increase in the number of capacitors. Behind the triac, they must be in pairs. In this case, the heat losses will be minimal. Sometimes the negative resistance in the network is a serious problem. Ultimately, overloading leads to a breakdown of the zener diode. Electrolytic capacitors with low-frequency noise are quite successful. The main thing in this case is not to give a sharp high voltage to the lamp.

Regulator circuit with high-mega-resistor resistors

The brightness control of this type can be used to control lamps of different types. Its circuit includes high-megamonic AC resistors , as well as a conventional zener diode. The thyristor in this case is installed next to the condenser. To reduce the frequency limit, specialists often use fuse- type fuses . They are able to withstand the load at the level of 4 A. In this case, the limiting frequency at the output will be a maximum of 50 Hz. Triacs of general purpose input voltage can withstand at 15 V.

Switches with FET regulators

Switches with a brightness regulator on the FET are good protection. Short circuits in the system occur quite rarely, and this, of course, is an advantage. In addition, it should be borne in mind that zener diodes for regulators can only be used with the KU202 marking. In this case, they are able to work with low-frequency resistors and deal well with interference. Triacs in the circuits are located behind the resistors. The limiting resistance in the system must be maintained at 4 ohms. Input voltage resistors hold approximately 18 V. The limiting frequency, in turn, should not exceed 14 Hz.

Regulator with trim capacitors

The dimmer control with trim capacitors can be used successfully to adjust the power of fluorescent lamps. Switches in this case should be located behind the diode bridge. Zener diode in the circuit is needed to suppress interference. Resistors of a variable type, as a rule, can withstand a maximum resistance of 6 ohms.

At the same time thyristors are used exclusively to maintain the voltage at the proper level. Triacs through themselves are capable of passing current at around 4 A. Fuses of a fusible type in regulators are quite rare. The problem with the electrical conductivity in such devices is solved by using a variable resistor at the output.

Model with a simple thyristor

The brightness control of light with simple thyristors is most suitable for button models. The protection system, as a rule, does not exist in it. All contacts in the regulator are made of copper. Maximum input resistance of a conventional thyristor is capable of withstanding 10 V. For rotary controllers, they are not suitable. Precision resistors with such regulators can not work. This is due to the large level of negative resistance in the circuit.

High-frequency resistors are also installed quite rarely. In this case, the interference level will be significant and lead to an overload of the zener diode. If we talk about conventional table lamps, it is best to use a conventional thyristor for a couple of wire resistors. The conductivity of the current is at a fairly high level. They rarely overheat, the power dissipation on average fluctuates around 2 watts.

The use of variable capacitors in the circuit

Thanks to the use of variable capacitors, it was possible to achieve a smooth change in the brightness of incandescent lamps. In this case, electrolytic models work quite differently. Transistors for such capacitors are best suited for 12 watts. The input voltage must be maintained at 19 V. Also use fuses. Thyristors, as a rule, are used with the marking KU202. For rotary modifications, they fit well. To increase the conductivity coefficient, potentiometers are used with circuit breakers.

Single-Shift Controller

The unijunction light dimmer is famous for its simplicity. Resistors in it, as a rule, are applied at 4 watts. At the same time, the maximum voltage it is able to hold at 14 V. When using it, it is important to consider that during operation, the light bulb can flicker. Fuses in devices are used rarely.

At the input, the rated current can be a maximum of 4 A. Thyristors such as KU202 are able in such a system to work only on a pair with a diode bridge. A triac in the device must be connected behind a resistor. To connect the brightness control to the lamp, all contacts must be cleaned. The housing for the device is important to use dielectric. In this case, the safety of work will be guaranteed.