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12V supply with 4 Channel Relay Issue

Posted: Mon Sep 17, 2012 4:59 am
by eatonj
I have a 4 Channel Relay shield connected to Pins 10, 11, 12, 13 and Gnd of a USBdroid. Works fine while connected to USB port on the Laptop or an External 9V (9.42V actually). However when I connect 12V (11.43V actually) all 4 relays activate instantly. Same 12V supplies power to relay board in all cases.
Spec recommends 7-12V, Max 20V for the USBdroid.
Can anyone suggest a reason or is it a faulty board.

Re: 12V supply with 4 Channel Relay Issue

Posted: Fri Nov 09, 2012 5:21 am
by csconsulting
Sorry for the late reply, this is in the wrong forum section, thats why.

Do you have a multimeter? It sounds like you are missing an earth somewhere thats applying bias to the transistors and turning the relays on.