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Can you dim a lamp with an arduino module and a solid state relay? Answered

I bought a Crydom D2425 Solid State Relay 240 Vac 25 Amp relay and I've been able to use it in tandum with my arduino uno to turn on and off a desk lamp so far. I've been reading up on pulse width modulation and was wondering if it was possible to control the lamps light level (something more than just on and off) with it. All help is greatly appreciated.

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twcochran (author)2013-11-12

I've done this with MOSFET transistors, the only catch is that whatever light you are using needs to be able to run on DC; basically any incandescent, halogen, or LED. I was able to find fets that go up to 16A, so with a good heat sync you should be able to control just about any size you want. If you are anywhere near the capacity of your transistors you'll also need either a thermistor or intermediate means of turning your lights on, as there is a pretty substantial inrush current that can burn out your transistors.

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jzpearson (author)2012-10-31

I had the same curiosity about an arduino dimmer.
I tried it, and just like steve indicated, terrible flicker.
I am curious if it would be possible to use an audio amplifier (100watt), in conjunction with an arduino for controlling 'volume', to dim a 110v incandescent (60Hz) bulb.?

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steveastrouk (author)2012-10-15

SSRs, like the D2425, are usually zero crossing switched. You'll find that a lamp load will flicker terribly if you try and control it with an SSR. What you WANT is phase control, which you'll only get with a TRIAC and a firing circuit. Ideally, you want a zero crossing detector, to keep everything synchronised nicely.

Steve

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Would one like this do?

http://www.ebay.com/itm/Carlo-Gavazzi-Relay-TRIAC-RA2425-D06TFS27-SSR-ZS-240V-25A-3-32VDCT-/230860010322?pt=LH_DefaultDomain_0&hash=item35c0543352

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user

Find out if it has "random firing".

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rickharris (author)2012-10-15

To PWM an AC waveform you need to chop it on and off every half cycle.

As in the diagram below - the red part is off and the black on.

If your relay can operate at this speed then it may work.

Normally a thyristor is used to chop the AC with a trigger circuit that is set by the rising voltage of the wave form.

In Ac use the thyristor conveniently resets itself every half cycle.

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bwrussell (author)2012-10-15

I'm not sure at all but from the pieces I've picked up I believe you will need a transistor with a operat9ing frequency greater than the max PWM frequency you wish to use to achieve the switching speeds required for PWM. Maybe solid state relays are different though.

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