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Simple digitally controlled AC gate/relay/switch

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cjc061000

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Hello everyone,

I am pondering on starting a new pet project. It involves controlling a wall plug using a microcontroller. I want to turn on/off my living room lamp. simple i know but the analog side im unaware of what is out there.

I want to be able to turn off/on the wall outlet's AC 120V signal using the microcontroller. I have heard that IGBTs are used for this kind of work, since I know they can be used for DC, but not sure if it will work with AC from the wall.

*EDIT* Doing a bit more research, i have seen that Solid State Relays might also work.
I found a part that might work.
https://www.opto22.com/site/pr_details.aspx?cid=4&item=MP120D4
These seem a bit too big though. any other suggestions for creating a small pcb are welcome.

- Can you suggest which part in the market can be used (surface mount or small dip)
- Can you suggest a simple circuit to do this?

My guess to connect this is: LiveWall->Collector. Emiter->lamp. LampGND-> WallGND. MCU->Gate

Thanks all.
 
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If you are requiring only two state control, on or off, a commonly utilized device, as you have recently discovered, is the Solid State Relay (SSR). SSRs have several advantages over their mechanical cousins, including some devices offer built-in snubber circuits, opto isolation, lack of back EMF, longer MTBF, etc. Choosing the correct SSR for the application requires considering the power requirements of the device to be controlled, i.e., voltage and both load and surge current. The device driving the SSR is another factor to consider, in your case a microcontroller, the SSR control input requirements, i.e., I/O pin voltage and current sourcing capabilities.

There are numerous manufactures of such devices, Panasonic produces a reliable line of SSRs which I have used in past designs:

Panasonic AQ-G Relays Datasheet



**broken link removed**

The AQ-G SSR Relay line is available from many parts distributors, including Digikey and Mouser, in single quantities in the $5 to $7 USD range.

Of course when selecting a part you should always select a device which offers a safety margin over the designs minimum requirements.

BigDog
 

To control the AC power from the mains you need isolation between the control signal and the mains for safety, which the SSR provides with an internal opto isolator. Thus as bigdogguru suggested, I believe the best part for your requirement is one of the referenced SSRs. Trying to build you own will save you very little, if any, money and requires a more complex circuit.
 

To control the AC power from the mains you need isolation between the control signal and the mains for safety, which the SSR provides with an internal opto isolator. Thus as bigdogguru suggested, I believe the best part for your requirement is one of the referenced SSRs. Trying to build you own will save you very little, if any, money and requires a more complex circuit.

Thanks all for the replies. I just wanted to make sure I was not getting something that was just not going to work and waste time/money on it.
 

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