Easiest Way to turn low-power, 115 VAC circuits on/off


Can anyone recommend some easy ways to turn a 115 VAC device on and off using a digital pin off of an Arduino? I am thinking of the following types of circuits to turn on/off: 1) a small Compact Flourescent lighting load (total amperage </= 2 Amps AC and 2) a small AC-powered LED circuit (total amperage </= 2 Amps AC).

I want to avoid having to use a relay board with the “clack” noise associated with it when it opens and closes. Any ideas are appreciated.

There's no such thing as "low power." The circuits in your house are probably fused for 20A so an screwup in your circuit could easily deliver 2300W into your skin.

There used to be a thing called the "power switch tail". I don't know if it's still available.

SCR's or Triacs are available to switch mains voltage with no relay. Usually they're sold as a "solid state relay". Search for that.

The fluro load is most likely going to be inductive, while the LED psu could go either way. How you handle them depends on several factors.

Yes, you could use mechanical relays, Triacs or SSRs designed for the right types of load, but ensure they are ISOLATED, and all your wiring is SAFE - and FAIL SAFE !

it could be a good time to practice with the control methodology and code - then talk to someone experienced for the mains control.

The website for the Power Switch Tail mentioned by MorganS is here.

Thank you for the links!...... The Power Switch Tail looks exactly like what I want for this but I might economize with my own SCR or TRIAC circuit.

Thanks everyone!

but I might economize with my own SCR or TRIAC circuit.

You did ask for easy... If you do builld it yourself, don't forget the optical isolation!!! There are special optical isolators for driving TRIACs. And, it's a good idea to buy some extra components whenever you're experimenting with power-line voltage... It's pretty easy to fry something. And of course, 120VAC can KILL YOU, so BE CAREFUL when testing & troubleshooting!!!

Another option is a [u]Solid State Relay[/u]. (They have the TRIAC & optical isolation and everything else inside.) The high-power industrial kind with screw terminals are easy to wire-up and easy to mount, and reasonably safe as long as you hook-up the AC side when power is disconnected. Make sure to get one that can be controlled with 5V and that's rated for 120VAC (or more) and the required amperage (or more).

Yes thank you Doug! I was an ET in the Navy and I appreciate all of the advisories given by all who answered who have to assume that a lot of the people don't know a lot about the hazards of working with mains voltages....but I know enough to be REALLY dangerous! :slight_smile:

Thanks again everyone......I have been out of the electronics hobby area for awhile now and need a hobby to keep me out of the bars and whorehouses....