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

Step 3: Schema

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    4 Discussions

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    VincentT57

    1 year ago

    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?

    1 reply
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    bcsedlonVincentT57

    Reply 1 year ago

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

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    Orngrimm

    2 years ago

    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... ;)

    1 reply
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    bcsedlonOrngrimm

    Reply 2 years ago

    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.