trying to make a wireless door chime trigger a relay...

First off , get out the multimeter and check your voltage across the speaker wires. There most likely won't be enough current in it to operate a relay directly even if you get the needed voltage. From here you could build a simple transistrorswitch to trigger the relay. Of course you would have to do the math to get the needed specs, but IMO it would probably be the simplest method to achieve your goal.

You might use an NPN transistor as the switch. A diode going to the transistor base from one sife of the speaker wire with the emitter connected to the other wire may allow the transistor to work.

John Fields wrote>

Yes

--- The chime sound you're getting from the speaker is AC, so there's no way you could just hook a DC relay across the wires and have it be energized by the AC signal.

If you had enough power available out of those two wires it's conceivable that you could rectify the AC, smooth it, and use it to drive a relay directly, but it's not likely that you have enough power available.

In any case, it would be informative to know what's going on there, so if you could measure the DC resistance of the speaker when it's not hooked up to the wires and then the AC voltage of the signal across it when it's chiming, that would be the place to start, I think.

It would also be nice to know what the DC supply voltage used to run the receiver is, and if one side of the speaker is referred to either the supply voltage or to "ground", the supply return.

It would also be VERY nice to know if the circuitry is isolated from the mains, since that could very well keep an assumption from killing you!

What I have in mind is rectifying and smoothing the signal on the speaker wires and using the resulting DC to turn on a transistor which will in turn turn on a relay using the receiver's DC supply, and since you indicated that you do have a multimeter, we'll need for you to make the measurements outlined above and to post what you find before we can proceed.

When you make the measurements to determine whether the speaker wires are isolated from the mains, what you'll need to do is to completely disconnect the receiver from the AC mains and then measure the resistance from both sides of the speaker to both sides (and ground, if it's 3 wires) of the mains and post what you find. If it's completely isolated you should get a very high resistance from either of the speaker terminals to either mains hot or mains neutral. If it's not high, or if you get a low resistance between the speaker and ground or the speaker and neutral, then since your electronics knowledge is "pretty limited" it may not be a good idea to go any farther unless you get an isolation transformer for safety's sake.

-- John Fields

thanks for your help John, this is going to be a bit more difficult and/or dangerous than I imagined.

I will take your instructions and play with it just to learn, but I think this has gone beyond my "limited" skill-set.

In the meantime- since I posted this message, I found an existing circuit available in either kit form or completed. It does EXACTLY what I need it to do and it is in a small package ready to go

a remote control with either latching or momentary control.

hurray!