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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

safety is always good. thanks for posting the 'ible.<br><br>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.<br><br>If you connect the LDR in parallel, you will NOT be able to use it 0-100% since you will create a parallel circuit...<br>you know the formula: <br>1/Rtot=(1/Rldr)+(1/Radjust)<br>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...<br><br>just save the hassle and replace it with the LDR... don't go parallel... ;)
<p>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.</p>

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