Controlling 240V with arduino

Hi Everyone, I want to write a circuit up so that a device that runs on a 240V mains power can be controlled via arduino. Reading forum posts before me it seems I need a relay that can be controlled via 5V and can hold 240V?

Can anyone recommend a part that I can buy to solve this issue? Thanks Mathew


The best way is to use optocoupler and triac, more secure and quiet (no contact, no noise, no spark?)

I use the tuto gived in the wiring web site (excellent tutos)

Hope that helps


Fatastic, Tho I was looking forward to the 'Click' sound but nevermind . lol

Thanks for your help. Mathew

for the click, you can replace the optocoupler by a relay, but the triac is definetly more secure than a little relay?

but the triac is definetly more secure than a little relay?

Not so sure !

A relay does not have any exposed parts connected to 220V lines, or get an SSR 'Sharp has goos ones) the optocoupler is already in !

If you want an authoritative click you'll need a contactor

If you get one surplus they are pretty cheap. It's just a relay writ large.

You may have to get a much heftier transistor to activate one. If you choose one of these you will need a 24 or 28VDC power supply. If you look around you might find one that runs on a lower voltage but I've not seen one that runs on 5v.

Be sure it's a DC coil one, there are ones that have a coil that needs AC.

Your next project could be a motorized switch, they look so rube goldberg!