Dimmer light switch circuit with Triac

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Dimmer light switch circuit with Triac, potency control in loads as illumination of bulb. Dimmers are devices used to lower the brightness of a light. By changing the voltage waveform applied to the lamp, it is possible to lower the intensity of the light output. Although variable-voltage devices are used for various purposes, the term dimmer is generally reserved for those intended to control light output from resistive incandescent, halogen, and (more recently) compact fluorescent lights (CFLs) and light-emitting diodes (LEDs). Dimmers range in size from small units the size of a light switch used for domestic lighting to high power units used in large theatre or architectural lighting installations.

Attention: circuit working directly with the net of high tension, risk of fatal shock, care when handling the equipment. Always of it turns off of the net of energy before moving in the circuit.

About the 110V or 220V Dimmer Circuit with TRIAC

When the Diac terminal reaches its breakdown voltage (typically 30v), the DIAC conducts and allows the capacitor to discharge at the thyristor gate, causing it to conduction and the load to be fed. The network formed by C4 and R5 in parallel with the thyristor is to prevent the component from damage because when the dimmer is controlling inductive loads it can form high voltage spikes at switch-off time. So the capacitor absorbs the generated overvoltage and the resistor limits the discharge current of the capacitor over the triac.
The network formed by capacitor C1 and coil L1 serves as a filter to prevent the propagation of RF interference through the power grid.

You should use a fuse in series with the load to be controlled to protect against short circuit. The TRIAC can be chosen according to the load to be controlled. In this circuit, a TIC225D for 8 Amps at 400 volts is used. The TRIAC will get hot, so a heat sink may be required. Coil L1 can be constructed at home, with 40 turns of #22AWG wire in two layers of 20 turns on a ± 2 cm ferrite stick. The L1 coil and C1 capacitor are optional.

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  • Use a small heatsink in the Triac.
  • You can use an incandescent bulb or LED bulb (dimmable), a fan, speed a drill, soldering iron temperature and more.
  • You must use a fuse to protect the circuit, this fuse will have a nominal value 30% higher than the load to which it will be connected.
  • Also, optionally a switch can be used to turn off the circuit
  • The Triac to be used must be according to the load with at least 30% tolerance to the current. In relation to the voltage these should be at least 30% of the peak voltage where it is installed. The VPP is 155V in 110V and 311V in 220V.
  • You may need to change capacitor C1 to achieve full operation. Values between 69nF and 220nF can be tested.
  • Various TRIACs can be used according to your needs, only adapting the voltage and current you need. Common in market are Bta16-600, Bta16-700, Bta16-800, Bta41-600, Bta10-700, Bta12-700, T410-600, Bta24-800, Bt136-600, Tic226, TIC236, TIC246. Just watch out for the suffixes and codes of each Thyristor because they tell you what current and what maximum voltage they support.
  • The bulb used be the dimmable type (dimmable, dimmable, DIM, attenuators, adjustable). Dimmer switches for LED lights (dimmable) and Incandescent bulb.

Diagram schematic Dimmer light switch circuit

Diagram Schematic Dimmer Light Switch Circuit
Dimmer Light Switch Schematic

Printed circuit board Dimmer light switch circuit

Printed Circuit Board Dimmer Light Switch Circuit
Dimmer Light Switch Circuit Led Pcb Layout
Dimmer Light Switch Circuit Led Pcb Layout
Dimmer Light Switch Circuit Led Pcb Layout

Last Update: 22/11/2021 14:53

Part Value Description Quantity
Capacitors
C1, C2 100nF /630V Capacitor film 2
C4 47nF /630 Capacitor film 1
Resistors 1/4W
P2 470K Potentiometer 1
R1 10k Brown, black, orange, gold 1
R2 2.2K Red, red, red, gold 1
R3 470k Yellow, violet, yellow, gold 1
R4 330 ohms 1/2W Orange, orange, brown, gold 1
Semiconductors
D1 DB3 or equivalent DIAC 1
T1 TIC226 or equivalent, see text Thyristor Triac 1
Miscellaneous
LOAD Connect the load to be controlled. Terminal block 2 pin 5.08 mm 1
INPUT Connect the input voltage. Terminal block 2 pin 5.08 mm 1
L1 100µH Coil with current according to load 1
Wires, PCB, knob, box, solder, etc.

Attention: circuit working directly with the high voltage network, risk of fatal shock, be careful when handling the equipment. Always disconnect from the mains before tampering with the circuit.

If the circuit is used to control the lighting of bulb, the board can be inserted in the standard switch box and use the potentiometer instead of the switch to control the brightness of the bulb.

For use with LED bulb they must be dimmable, it cannot be used with ordinary LED bulb and fluorescent bulb, it can be used with halogen and incandescent bulb.

The Triac to be used must conform to the load with at least 30% tolerance relating to the current. As for the voltage, it must be at least 30% of the peak voltage of the network where it is installed. The PPV is 155V in 110V networks and 311V in 220V networks.

It may be necessary to change capacitor C2, to achieve full operation. Values between 69nF and 220nF can be tested.

Several TRIACs can be used according to your needs, just adapt the voltage and current you need. Common ones in our market are Bta16-600, Bta16-700, Bta16-800, Bta41-600, Bta10-700, Bta12-700, T410-600, Bta24-800, Bt136-600, Tic226, TIC236, TIC246. Just pay attention to the suffixes and codes of each Thyristor because they tell you what current and what maximum voltage they support. You can use other equivalent Triacs.

Download files for this project – PDF PCB, Schematic in PDF, silk screen.

Download

Mirror 1

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