Friday, February 25, 2022

3500W Dimmer for 110V or 220V using TRIAC TIC246 with PCB

Fig. 1 - 3500W Dimmer for 110V or 220V using TRIAC TIC246M with PCB

This is a dimmable load controller circuit, its operation is based on the control of the sine cycle, keeping it off during a small period of the wave. And work only for a specific part of the wave keeping the load with part of the wave controlled by period, similar to PWM.

With this type of circuit we can control the intensity of an incandescent light, ceiling fans, resistive load, among others, through the decay of the cycle regulated through a potentiometer.

The Dimmer Circuit 

The 3500W Dimmer for 110V or 220V using TRIAC TIC246M with PCB circuit diagram is shown in Figure 2 below. 

It uses a 16 Amp TRIAC TIC246, this is enough to handle loads up to a little over 3500W, obviously with heat sink.
Fig. 2 – Schematic Circuit 3500W Dimmer for 110V or 220V using TRIAC TIC246M

If you need to increase the power of the circuit, you can replace the thyristor in the circuit. Using the simple formula of Ohms Law, P = V * I, through current and voltage, we can find the power of the circuit with each of the Thyristors:
  • TIC246 = 16A:
    • At 110V => P = 110 * 16 = 1760W
    • At 220V = P = 220 * 16 = 3,520W

  • TIC256 = 20A:
    • At 110V => P = 110 * 20 = 2,200W
    • At 220V => P = 220 * 20 = 4,400W

  • TC266 = 25A:
    • At 110V => P = 110 * 25 = 2750W
    • At 220V => P = 110 * 25 = 5,500W


This circuit works directly connected to the 110/220V electrical network, and has a high power load, any carelessness, or wrong connections, error in the project, or any other occasion, can lead to irreversible damage. 

We are not responsible for any type of event. If you do not have enough experience to assemble this circuit, do not do it, and if you do, when testing, be sure to have the proper protections and be accompanied by someone else.

How it works

When we connect the AC mains to the circuit, there is a charging of the capacitor C4 through the voltage set in the Trimpot RP1. When biased, there is a sending of this voltage to the DIAC through the current limiting resistor R3

The DIAC is a bidirectionally biased diode, and is triggered when it reaches its breakdown voltage, about 30V, as it is connected to the Gate of the TRIAC. As soon as it reaches its breakdown voltage, both positive and negative pulses are activated in the Gate of the TRIAC

However, this also charges the capacitor with reverse voltage from the negative half-cycle, and in this charging time the TRIAC stays open until the cycles compound.

This is repeated with each cycle of the AC sine wave signal from the grid, which maintains its drive and cut cycle repeatedly, leading to an output voltage lower than that of the input.

The network formed by capacitor C1 and coil L1 works as a filter to inhibit RF spurious propagation through the power network. While R1 and C2 are employed for transient reductions.

The network formed by C4 and R5 in parallel with the TRIAC, serves to prevent the TRIAC from burning out, because when the dimmer is controlling inductive loads, reverse voltage spikes are formed at the moment of switching. 

Thus, the capacitor absorbs the generated overvoltage and the resistor limits the discharge current from the capacitor onto the TRIAC.

The resistor R4 connected in parallel, is used to decrease the ohmic rating of variable resistor RV1, since the applicable value for RV1 is 150k ohms.

Since it is not easy to find this variable resistor, we made an association of resistors to get it close to 150k ohms.

The network formed by capacitor C1 and coil L1 works as a filter to inhibit RF spurious propagation through the power network.

The L1 coil consists of a small ferrite rod, 1/4" diameter and 11/4" long, wound with 55 turns of 28 SWG enameled copper wire.

You can be using the ferrite coil from a PC power supply to make your coil, or you can be buying a commercial 40uH coil. 

Components List

  • Semiconductors
    • U1 .............. TIC246 Triac *See Text
    • D1 .............. DB-3 DIAC Diode

  • Resistor
    • R1 ................ 56Ω (green, blue, black, gold
    • R2 ................ 2K2Ω (red, red, red, gold)
    • R3 ................ 5K6Ω (green, blue, red, gold)
    • R4 ................ 390Ω  (orange, white, brown, gold)
    • R5 ................ 250KΩ Potentiometer
  • Capacitor
    • C1, C2, C4 .... 100nF / 600V Polyester Capacitor 
    • C3 ................. 47nF Ceramic/Polyester Capacitor

  • Miscellaneous 
    • P1, P2 ......... 2-pin PCB soldering terminal blocks
    • F1 ................ Fuse 15A with soldering terminal blocks
    • L1 ................ 40uH Inductor *See Text
    • Others ......... PCB, heat sink, wires, etc.

Printed Circuit Board

We are offering the PCB - Printed Circuit Board, in GERBER, PDF and PNG files, for you who want to do the most optimized assembly, either at home.

If you prefer in a company that develops the board, you can is downloading and make the files in the Download option below.
Fig. 3 - PCB - 3500W Dimmer for 110V or 220V using TRIAC TIC246M with PCB

Files to download, Direct Link:

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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My Best Regards!!!

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