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Topic: controlling 12v and 220v circuits (Read 4144 times) previous topic - next topic


Hello All!
(hope I'm posting it on the right forum...)

I'm planning an Home Automation system using the Arduino Board.
I looked A LOT around the internet and still couldn't find specifically what I was looking.
I need two things which are theoretically pretty similar but I know they are not... (different electronics).
I'm interested in using the Arduino to trigger a 12v circuits in order to connect 3w/10w RGB LEDs (for "mood" light) using an external power source (so I can control many of them).
a sample of something like this is this:
I guess it shouldn't be that difficult and I rather build this than buy this... (cheaper and MORE FUN!).

The second thing is doing the same but with a regular 220v Incandescent light bulb, so I can control my home lights.
I know I should be using an SSR but I also understand that an SSR alone cannot do the job because It has to be connected to some circuit that identifies Zero-Crossing for it to work well.
I know all about being careful dealing with high voltages.
I guess there is no problem using an external TLC5940 to get more PWM exits for controlling more outputs. the Arduino should only be the trigger.

I wandered all around different electronics sites, Arduino sites and more and couldn't find a SPECIFIC circuit (and a sketch). in each of the sites there are many different recommendations and on every reply that someone wrote, there are at least 2 other replies saying that is should be different.
Like I said, nothing specific... (I'm sure there are, but couldn't find'em).

I would be more than happy if someone can guide me and share some sketches of working (or known as working) circuits and components I should buy in order to build them.
after all, I'm not looking for "squeezing the juice" out of the Arduino, only controlling other circuit using PWM...
it's only 5v controlling 12v circuit (which I believe is easier).
and a 5v controlling 220v circuit.

Thank You all very much!


Feb 09, 2011, 11:35 pm Last Edit: Feb 10, 2011, 12:05 am by Grumpy_Mike Reason: 1
I know I should be using an SSR but I also understand that an SSR alone cannot do the job because It has to be connected to some circuit that identifies Zero-Crossing for it to work well.

You are wrong about this. Dimming SSRs work autonomously.

like this one:-


For controlling the 220v circuits, you'll need a relay.

I'm in the process of doing a project with similar requirements and have come up with the following schematic (see attached).

It's a lot like other relay driver circuits available on the net, just using a ULN2003A to drive instead of individual transistors.

That circuit is modified from my original post with LEDs to indicate status (that one needs a rework to move the LEDs off the 12v rail to the 5v input) that I posted here http://arduino.cc/forum/index.php/topic,51342.0.html

If you're sourcing 5v relays, you can just change the 12v VCC to 5v. You'll need to have a separate power source to drive the relays (even with 5v) as:
a) the arduino doesn't have enough grunt to drive multiple relays directly
b) you want to protect the arduino from the back current generated by the relays disengaging.

The ULN2003 covers a) and b) for for you directly, but if you're going to use SSRs, I'm not sure b) applies.


I think I didn't make myself clear...
I want the lights to be dimmable, so I cannot use a relay.
Gorbs, I can use your circuit with relays for trigerring a garden watering system or even a shower boiler but not for dimming lights.

and Mike, that SSR costs almost a $100 A PIECE...
I'm sure there's a way to build one, much much cheaper...
I need your help, all the electronics geeks...  :)

I need something like this:

I know this one is very dangerous but all I need is the circuit, and I'll buy the components and build it myself inside a closed box.
What I need is the circuit sketch and list of components.



that SSR costs almost a $100 A PIECE...

How much does your house cost?  Say, if it burned down because you screw up?

Look for SSRs at surplus sites like allelectronics.com, or on ebay.




I'd suggest replacing your light switches with these and then using infrared from the Arduino to control them.  Cheap, complete isolation, certified products - happy days.


and Mike, that SSR costs almost a $100 A PIECE...

Yes but it is rated at 50Amps, you can get much smaller ones. It is just it was the first one I came across.


daveg360 has a good idea.

Someone has interfaced X10 to the arduino, IIRC.  That's another option.



Highly recommend some isolation too.  Preferably opto-isolators such as the Sharp PC817 series.  http://www.google.com/search?client=ubuntu&channel=fs&q=Sharp+PC817&ie=utf-8&oe=utf-8

I attached the datasheet.  I also attached a neat project using SCR's and Christmas light you might be interested in.

- Regards
Arduino UNO R3

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