Build Your Own Relay-Triggered Power Cord

Build Your Own Relay-Triggered Power Cord

I’m a big fan of the PowerSwitch Tail. It’s an awesome power cord equipped with a relay board that enables a relative neophyte maker (say, can run the Blink sketch in Arduino) to safely control high-voltage electrical sources. It’s great because it’s pretty much foolproof and as safe as any extension cord.

Ryan Edwards of Sparky’s Widgets shot this YouTube video showing how to build a DIY version of the PowerSwitch Tail that can switch up to 120VAC/12A.

YouTube player

Ryan reports that the total cost is under $20, which doesn’t compete much against the $27 PowerSwitch Tail (available at the the Maker Shed) but it’s always cooler to make one yourself!

12 thoughts on “Build Your Own Relay-Triggered Power Cord

  1. JD90 says:

    “This video does not exist”

    1. John Baichtal says:

      Oops, apparently he’s disabled embedding… here’s the URL to his YouTube page:

      1. Sparky's Widgets (@SparkysWidgets) says:

        I saw a lot of traffic this morning :)
        Great to see this video get onto Make! Thanks for the shoutout John!
        Also the video should embed(I have it switched on for play everywhere)

        1. JD90 says:

          I still don’t see it here, I think this is the intended link:

          1. iso2013 says:

            That one still doesn’t work, at least for me.

  2. Alan S. Blue says:

    Having used the PowerSwitch Tail, I’ll note that the cords are very rarely a good length.

    If you’re making your own, make it with a IEC C13 on one side, and an IEC C14 on the other. That is, the standard computer in-and-out plugs and receptacles. Or at least the US standard NEMA 5-15 plugs and sockets. (Or local equivalents).

    Quite a few bins of “antique electronics”, and a significant slice of that is just the heavy duty power cords. Make it without a cord, make it easier to store.

  3. ameyring says:

    There’s a safety concern with the drilling – I suggest drilling with the plastic on a stable surface so you don’t drill into your fingers :-)

    Otherwise, a useful video with an alternative place to get these relays. I do know of a source of a different relay to do the same job, but when I inquired into it, it was a two-month wait.

    1. Sparky's Widgets (@SparkysWidgets) says:

      You are right about the drilling, I am a bit cavalier which such things, but its really a good idea to secure the object to be drilled without using ones fingers :) Also those relays are a bear to get ahold of I have since had to switch to RZSchracks and order them well in advance. This relay form factor really makes the most sense but is losing out in terms of popularity it seems.

  4. Sparky's Widgets (@SparkysWidgets) says:

    I just updated the relayPCB ( ) project page with github repo info of this same project (master is of course most current version), for those more interested in a brief write up I will get one up but the video does a pretty good job of showing the basic idea!

  5. Paul Bonneville says:

    Apparently the author of the relay video pulled it down and removed it from his site…

  6. Laughmore says:

    Still no video or relevant details in 2017

Comments are closed.

Discuss this article with the rest of the community on our Discord server!

My interests include writing, electronics, RPGs, scifi, hackers & hackerspaces, 3D printing, building sets & toys. @johnbaichtal

View more articles by John Baichtal
Maker Faire Bay Area 2023 - Mare Island, CA

Escape to an island of imagination + innovation as Maker Faire Bay Area returns for its 15th iteration!

Buy Tickets today! SAVE 15% and lock-in your preferred date(s).