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5v DC Relays and Arduino

Posted: Sat May 04, 2013 1:50 am
by william_stevens
I want to create my own circuit board to run 8 x 240v rope lights controlled by the Arduino Eleven (4 reindeers in motion). Are there any examples available that show the 240v input to 8 output? I have looked at a couple of kits built by other people but the details are always incomplete. Anything that shows 240v items controlled by Arduino boards would be helpful. :roll:

Re: 5v DC Relays and Arduino

Posted: Sat May 04, 2013 2:15 am
by william_stevens
If you sell anything that would suit the function, just let me know.

Re: 5v DC Relays and Arduino

Posted: Thu May 09, 2013 9:56 pm
by angusgr
Hi William,

Sorry this post didn't attract any replies earlier. However, please don't make duplicate posts in multiple forums - if you change your mind about where to post, please delete the original thread before you create the new one. I've taken the liberty of deleting the duplicate post.

Working with 240V mains is inherently very dangerous, and certain types of homemade 240V wiring may not be legal depending on where in the world you are located. If you are unsure about how to proceed with a project that involves 240V, please don't do so. Consult an electrician or an electrical engineer before plugging in any 240V project.

Freetronics has no off the shelf solution, but we do have some products that may be of use in designing and constructing one. The relay8 relay driver shield can drive up to 8 relays with coil voltages from 5v to 24v: ... ver-shield

You can get standard DIN rail mount relays (or relay sockets) from electrical suppliers, or there may be other options you can connect using screw terminals. The whole assembly will need to be designed to be safely wired and installed in a safe insulated enclosure. Again, please don't consider this project until you have sought out the knowledge required to do it safely and in a way that meets the standards of the country you are in.

A safer option would be to use a set of wireless remote control power points. This way the 240V stays encapsulated in a predesigned approved product, and you just send RF signals to turn each one on and off.

One way to do this is to send the 433Mhz signals yourself. You can use remote control power points like this (that model supports up to 8) with a 433MHz transmitter module like this and an Arduino library like this to generate the signals. Those URLS are for Australia (though not Freetronics products), I've used these devices in combination before to control a single power point. Assuming none of the internals (chip types, etc.) in that power point model have changed it should still work.

There are other alternatives people have used successfully too, you can find them online if you search for similar keywords.

A final alternative to sending RF remote control pulses directly from the Arduino is to hack open the remote control transmitter and use the Arduino to drive its button presses directly, something like this.

Hope this helps,


Re: 5v DC Relays and Arduino

Posted: Thu May 09, 2013 10:42 pm
by angusgr
Ah, I forgot other Freetronics people have done this too!

A chapter in Jon Oxer's Practical Arduino book, and also our own John Boxall ("tronixstuff").