230V AC PWM Dimmer Controlled by Arduino, Raspberry Pi

Cheap, easy, galvanic isolated and powerful 230VAC dimmer controlled by PWM output from Arduino, Raspberry Pi etc.

Step 1: How Does It Work

Buy cheap AC dimmer on eBay, which is controllable by manual adjustable resistor. http://www.ebay.com/itm/4000W-AC-220V-SCR-Voltage-...

Connect parallel to manual adjustable resistor photoresistor, place photoresistor to dark box together with LED.

Control LED light by PWM output.

Step 2: What Do You Need

• AC dimmer http://www.ebay.com/itm/4000W-AC-220V-SCR-Voltage-...
• Photoresistor eg VT431N http://www.promelec.ru/pdf/DTS_vt400.pdf
• LED (white)
• resistor (approx 20kOhm)

Step 3: Schema

Comments

[VincentT57]

I received same dimmer, but it doesn't work. Above rotating potentiometer, it has one more variable resistor (blue box). I just guess it have to be adjusted to some Ohms, I tried all, but dimmer still produce full voltage. Guys, can you help please, what to do with it?

[bcsedlon]

How did you test it? Best way is use old style bulb with fiber.

[Orngrimm]

safety is always good. thanks for posting the 'ible.

I really would suggest to remove the adjustable resistor and have only the LDR there. Be sure your LDR and the removed adjustable resistor have the same value-range to be able to use 0-100% PWM.

If you connect the LDR in parallel, you will NOT be able to use it 0-100% since you will create a parallel circuit...
you know the formula:
1/Rtot=(1/Rldr)+(1/Radjust)
so the worst thing: if you have the adjustable resistor on 0ohm, would will always have 0 ohm across all. with changing the adjustable resistor, you change the complete range of possible PWM...

just save the hassle and replace it with the LDR... don't go parallel... ;)

[bcsedlon]

You are right. During my test adjustable resistor was so high that I was able control full range in parallel connection. This gives a possibility to control manually or by PWM. For sure adjustable resistor has to be set maximal resistance position to control only by PWM.