Dimmer circuits

That are the AC light dimmer circuits. We can control a light bulb, speed AC motor. They use the TRIAC and SCR as main components, and adjust potentiometer and switches. See more projects circuits below:


1. Low volts AC Dimmer for 6.3V Lamp

AC Dimmer for Lamp 6.3V

This is a low voltage AC dimmer circuit, for lamp 6V. While friends may not see the benefits of this circuit. But I think the advantage in the first step, we will be learned the TRIAC work. And have high safety , because of use AC Low Voltage.

Which they has the working is simple, the UJT-Q1,D1,VR1,C1,R1,R2 will generate frequency to TRIAC active, then it makes the Lamp bright up.

With working rate of the TRIAC can control by R1 – potentiometer or it is simple dimmer.

We may apply other level voltage power supply for example 12VAC.
The Q1 use UJT – 2N4891 or others.

Hope this circuit will be ideas for friends.


Very cheap AC light dimmer

Very cheap ac light dimmer
Next,this is a very simple AC light dimmer circuit,easy and cheap.

In above circuit, we use the dimmer circuit with the power line,so we must be very careful.

Turn on S1 to ON and Select S2 to dimmer mode.

We use a capacitor in series with a lamp, the capacitor reduce power to lamp.

The S2 is an option to output size to full size or less.

The value of the capacitor C1 depends on the size and power of the lamp brightness as required.

We may use several capacitors, to select the different capacity.

The C1 capacitor should be a polyester capacitor type or metalized polypropylene capacitors type, and higher voltage than 300V.

Do not use the electrolyte capacitor in this circuit .

If the output short circuit, C1 capacitor is damaged immediately.

AC 100W lights dimmer using a triac

Simple AC light-dimmer-120watts

This circuit has can to turn down a light bulb arrives at 100W. If Triac there is tall temperature should hold Heat Sink or let off the heat. The Diac be diode that perform be formed encourage or Trigger Diode 2 kinds are way or Bidirectional. The VR1 use for fine decorate turning down fire. Caution this circuit must is in a box closes all the time that have the electricity flows through.

AC lights dimmer circuit using Triac and Diac

In figure 2 well than the first circuit

Operation of the circuit be Lamp L1 is adjusted by adjusting the light of VR1. This will serve to control the speed of charging of C1, Because triac will work.
When C1 has charged to the voltage at the triac work.When adjusting the VR1 C1 will charge as little faster lamp is lit.If the adjustment of VR1 C1 will charge very slowly.The little light bulb. Because the triac does not work over the triac during the work.The light bulb will dim down by adjusting VR1.The R1 is placed for protection VR1 prevent damage.The R2, C2 is used to eliminate signal disturbance. Both produced and external circuit.


1200 Watt AC Dimmer by Triac Q4006LT

This is Power AC Dimmer 1200 watt size. It is use a triac Q4006LT. Friends ever tour is the foreign land has and to ever reach rest a hotel. On bed head has will head bed fire decorates. It has a button opens-close and a button controls the brightness with the equipment this/these be AC Dimmer follow our circuit can fine to decorate.

1200 Watt AC Dimmer by Triac Q4006LT

The VR1 for control the light besides when friends apply TRUE work. The Q1 -Q4006LT , should hold heat sink with and should be careful specially prohibit catch one ( part ) which part in the circuit , because read will bump against the electricity can suck. I hopes this circuit , friends can induce apply be AC Dimmer with electric other appliances bump against emphasize kind coil heat equipment , be lucky please yes.

pcb-layout-of-1200-watt-ac-dimmer-by-triac-q4006lt
Figure 2 the pcb layout and Components layout of this circuit.

Note: Fuse you should as current load. for example we use 100Watt lamp we will use fuse current is 100 watt / 220V = 0.45A or 0.5A.

Mr Gerson said about: 1200 Watt AC Dimmer by Triac Q4006LT
How can this be a 1200W dimmer when it uses a 0.5A fuse? If anything it should be 5A fuse no?

Sounds more like a 120W dimmer by the maths.

Let’s justified with calculation:

Power (apparent since AC) = VI(rms) = 220Vac x 0.5A = 110VA (max, due to limitation of fuse)

Let’s assume a power factor of 1 (not possible in real life, unless 3 phrase)

Power_in (max) = 110W.
Power_in (let’s said pf=0.7, realistic case) = 110 x 0.7 = 77W, this is more realistic power input.

So if power input is only about 77W, please tell me how it could output 1200W? It’s impossible according to law of conservation of energy. The fuse will just BLOW every time it switches on at full brightness.

To get 1200W input for typical realistic case, you need
fuse rating (Irms) = Pr / (V * pf) =
= 1200 / (220 * 0.7) = 6.5A

Sure you may not need that many current since it is a dimmer, but at maximum brightness you need 6.5A otherwise i’m sure something will blow (the fuse).

9 Comments

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