Strange 3-way switch

Thread Starter


Joined Jun 3, 2008
5's a strange one. I constructed a three way switch using: a 12v, 100ma PS, two SPDT switches, two NTE R72 relays and two LEDs. Both switches control another connection simply open/closed, but the key is that when either switch is thrown the LEDs go on (or off as the case may have it). The relays have NO/NC cross connected to enable the three way. The switches are separated by 220' and it is really helpful to have the indicator LEDs and the three-way feature--but a serious bit of walking to test them.

Currently the LED merely goes from on to on and bright, not on and off as previously. I have swapped out a relay (as I do not believe one of them is working, the other I have confirmed is working). I have checked every connection and even re-soldered all of the connections on the side which got the new relay.

Lastly, this on and then on and bright when either switch is thrown is the behavior I had before the new relay and all of the soldering.

I have even tried a benchtop PS and different voltages and current--nothing but an even brighter version of the same problem. All that being said, on two occassions today I did, for five minutes each time, have it working properly.

Any wisdom, insight, suggestions would be appreciated.