Simple circut

[randyallen]

HI,

This is my first post. hopefully someone can help me out. I have created a device to melt the verdigris on Steinway piano hammer flanges. Basically it is 12 volts, 2 Amps AC running through a of pair of insulated tweezers. Squeeze the tweezers together on a metal piano center pin and a short is created. The heat generated melts the verdigris in a couple of seconds. It works fine but I would like to a have a beeper or buzzer sound when the temporary short circuit is created. For safety's sake.

 

[Martaine2005]

How about showing your circuit?.
The batteries need charging in my crystal ball.

Martin

 

[Bluejets]

Fit a 12v AC relay across the supply.
Connect the buzzer to the normally closed contacts.
When the voltage drops due to the short, the relay drops and turns on the buzzer.
Naturally you would need another supply for the buzzer.
If AC relay hard to find, fit a bridge rectifier to just the relay coil section.

 

[randyallen]

Fit a 12v AC relay across the supply.
Connect the buzzer to the normally closed contacts.
When the voltage drops due to the short, the relay drops and turns on the buzzer.
Naturally you would need another supply for the buzzer.
If AC relay hard to find, fit a bridge rectifier to just the relay coil section.

Thanks! This is good information. I'll report back after some experimentation utilizing your suggestions.

 

[randyallen]

Thanks! This is good information. I'll report back after some experimentation utilizing your suggestions.

YES!!! I installed a DPDT AC relay and it works as advertised. Very cool! There is a caveat, though. Because I'm using a 9 Volt battery to power the buzzer, it stays on once I unplug the main power. No problem, I will incorporate a small AC to DC transformer to power the buzzer which will source from the main power.. Maybe from my box of wall-warts. I should then be good to go. Thanks so much for sharing your knowledge.

 

[Bluejets]

There is a caveat, though. Because I'm using a 9 Volt battery to power the buzzer, it stays on once I unplug the main power

Yes I was fully aware of that but thought you would be able to sort it for yourself.
One could simply use a normally open momentary contact push button in the buzzer circuit also to operate as a "push-to-test."

 

[randyallen]

I had to laugh when the buzzer stayed on. Don't know why. Guess I was just glad it all worked. I found and ordered a compact power supply online - about the same size as a 9 volt battery. Seems like a viable solution. I'll let you know and may be back more questions. Thanks, again.
https://www.trcelectronics.com/View/Mean-Well/IRM-15-12.shtml