Many electronics circuits and projects for learning in simple ways.

5 Simple Dimmer circuits

If you are looking for the AC light dimmer circuit. Here is simple and TRIAC dimmer circuit.  They can control a light bulb, speed AC motor. They use the TRIAC and SCR as the main component, and adjust potentiometer and switches.

See more projects circuits below:

5 Dimmer circuits

1.) Low volts AC Dimmer for 6.3V Lamp

Low volts AC Dimmer for 6.3V Lamp

This is a low voltage AC dimmer circuit, for lamp 6V. While friends may not see the benefits of this circuit. But I think that its advantage in the first step, we will learn the working of  TRIAC. Second, high safety, because of Low AC Voltage.

Which they have the working is simple.  The UJT-Q1, D1, VR1, C1, R1, R2 will generate frequency to actives the TRIAC. Then it makes the Lamp bright up.

Which the working rate of the TRIAC can be controlled by potentiometer-VR1.

So It is simple dimmer.

We may apply other level voltage of power supply, like  AC12V.

The Q1 is UJT – 2N4891 or others.

I hope this circuit will be ideas for friends.

2.) Very Cheap AC light dimmer circuit

Very Cheap AC Light Dimmer

Next, this is a very simplest AC light dimmer circuit, easy and inexpensive.

In the above circuit, we use the dimmer circuit with the AC power line.

So we must be very careful.

How it works
Turn on S1 to ON and Select S2 to dimmer mode.

We use a capacitor in series with a lamp. The capacitor reduces power to the lamp.

S2 chooses an output power, full or less.

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

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

C1 should be a polyester capacitor or metalized polypropylene capacitors.  And higher voltage than 400V.

Do not use the electrolyte capacitor in this circuit.

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

3.) AC 100W Lights TRIAC Dimmer circuit

AC 100W Lights Dimmer Using A TRIAC

This is a simple AC TRIAC dimmer circuit. This circuit can dim the lamp up to 100W. If the TRIAC is a high temperature. It should be held with a large heat sink.

The DIAC(Diode AC bi-directional switch) is kind of diode. It switches AC voltage or trigger to a gate of the TRIAC.
Adjust  VR1 to dims the brightness of the lamp.
Caution!  this circuit must be in an electricity insulation box that closes all the time. It has high voltage electricity flows through.

4.) AC light dimmer circuit using TRIAC and DIAC

AC lights dimmer circuit using Triac and Diac

 AC light dimmer circuit using TRIAC and DIAC (update from the Previous circuit)

Operation of the circuit
The lightness of lamp-L1 is adjusted by  VR1.  The VR1 controls 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.

R2 and C2 eliminate the disturbance signal, both inside and outside the circuit.

5.) 1200 Watts AC TRIAC Dimmer circuit

This is Power AC Dimmer 1200W. It uses the 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 of the equipment this/these be AC Dimmer follow our circuit can adjust to decorate.

1200 Watt AC Dimmer by Triac Q4006LT

The VR1 for control the light beside when friends apply for 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 hope this circuit, friends can induce apply be AC Dimmer with electric other appliances bump against emphasize kind coil heat equipment, be lucky please yes.

Figure 2 the pcb layout and Components layout of this circuit.

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

Good suggestion

Mr Gerson said about: 1200 Watt AC Dimmer by Triac Q4006LT
Why is 1200W dimmer when it uses 0.5A fuse? Is it should 5A fuse?

When you 0.5A fuse. It should be 120W dimmer by the maths.

Let’s calculate again:

Power (apparent since AC) = VI(rms) = 220Vac x 0.5A = 110VA (maximum, because of limiting of fuse)

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

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 the law of conservation of energy. The fuse will just BLOW every time it switches on at full brightness.

To get 1200W input for the typical realistic case.

You need:
Fuse rating (Irms)
= Pr / (V * pf)
= 1200 / (220 * 0.7)
= 6.5A

Sure! You may not need the many currents. Since it is a dimmer. But at maximum brightness. You need to use 6.5A current. Otherwise, I am sure something will blow (the fuse).

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This Post Has 10 Comments

  1. what is the name of software this schematic is created by?

  2. how can i design atriac circuit to control speed of motor 0.5kw?

  3. can i havve the ckt for time period of 10 sec

  4. I’ll try to use R2, C2 to eliminate the noise. thx.

  5. Can you be mo specific on what kind of diac to use in you figure 2 by L circuit?


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  8. sir, i have 0.36uf/400v capacitor, what are the changes needed to the circuit

  9. The English in this article is very poor, at times its hard for a student such as myself to understand. I ask the author to please make an effort to fix this otherwise fantastic article.

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