EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: edy on August 30, 2014, 06:59:31 pm
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Hi folk,
I have a piezo-electric tool that has 2 wires going to it (red and green) from what I presume to be the signal transducer or generator unit that powers it. The tool unplugs from the cable with 2 wires. It wasn't working so I thought the cable must have a broken wire so I thought I would use my continuity tester on the multimeter to check it out.
To my surprise, probing the green and red wires at the same time I had continuity. Obviously this would make no sense if it was a DC supply as it mean they were shorted to one another. But somehow this is happening in this AC supply and I am trying to understand how I can have continuity between both leads heading to the piezo-electric tool. Both green and red leads are somehow connected inside the generator or shorted in some way, yet both are necessary to power the tool.
I'm thinking the green/red wires form a continuous loop that is electrically isolated in the power supply but that runs through a transformer. So I can get red/green continuity and the AC transformer drives or oscillates the polarity which causes the piezo-electric to vibrate.
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More information is required.
A piezo transducer is capacitive so should normally read open circuit but it probably isn't just a transducer.