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5v usb powered relay

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  • 5v usb powered relay

    This is doing my head in
    I need to switch on/off a 12volt powered 5v regulated power supply when my laptop fires up/shutdown via the laptops usb port (so I can power a usb hub). I tried a few 5v solid state relays but they dont work I ended up with high resistance on the load side of the relay, so Im assuming from my basic eletricky knowledge that they are not suitable for this application. Can anyone post up a link to a suitable relay(ebay) and anything else I need to get this final headache done
    Thanks in advance
    Last edited by Wozza; 09-14-2012, 09:36 PM.

  • #2
    Not that I like solid state relays, but a 5V SS relay should work, unless it's intended for an AC load.

    But google 5V relays and you should find various examples including mechanical relays with 20mA & 40mA coil currents costing ~$5.


    • #3
      Thanks Oldspark
      Hmmmm didnt think an AC load would make a difference... but double checked and 1 set are DC load the other where AC
      I grabbed one of everything in the 5v range at my local Jaycar store
      I did just that(googled 5v relays) and its like being 5yo with a pocket full of money in a sweet shop......... why oh why cant we just have 1 ver of everything


      • #4
        LOL! I knew many were for AC loads but some are for DC.
        However checking my Jaycar catalog, only ONE is for DC! (Except for others that switch ON when power is OFF, all seem to be AC.)

        LOL x2 - now I really don't like SS relays ha ha! Even I was surprised to see how few DC-load SS relays Jaycar have. Not that I ever sought them (I prefer un-puncturable robust primitive mechanicals), but I thought more SS relays would be suited for DC loads.

        Damn it. I've done the UIBI and killed "smart" and diode battery isolators (for systems with charge lights). Maybe it's time for for a "true" solid state relay - dc or ac loads irrelevant!
        But I'll see what's on tonite's TV program first...


        • #5
          I'm using one of these:

          It's not just wired to 5V power from the PC, because in my setup I'll be running the PC 24/7, so it's hooked up to an arduino and switched that way, but if you give it a 5V signal it'll handle up to 5A @ 30VDC. They also have a bigger version: It'll handle 20A.


          • #6
            Thanks Guys
            finally got it working with this relay
            dont know what happened to the first one I tried(prob connected wrong and fried it)