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Sound activated switch problem with relay Help!? Answered


I bought a kit of electronic sound activated switch but the relay just turns of and on constantly. The power supply is 12v 500ma. i tried a power adapter 15v 1.2a from my router and it work but i cant find to buy one like that. Can i maybe put another relay to solve the problem or anything else?
Here is scheme and parts.

http://www.flickr.com/photos/54844690@N03/

Sorry for bad English

Thanks.

6 Replies

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Jack A Lopez (author)2010-10-15

I think your power supply is good, and the problem lies somewhere else.

I am guessing this circuit is designed to respond to short bursts of sound, like clapping one's hands, and that it toggles.  If it was off, then a clap of sound turns it on.  If it was on a clap of sound turns it off.

I did not understand this circuit at first, so I decided to re-draw it.  This drawing is attached below.  I see 3 stages:  sound detection stage, flip-flop stage, and output relay stage.

Try testing each stage independently.  If all 3 stages are working, then everything should work.

Also I am guessing the potentiometer is some kind of sensitivity adjustment on the sound detection stage.  Even if everything else is wired correctly, you might have the sensitivity turned up too high, and this is why it is reacting constantly.

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user
Re-design (author)Jack A Lopez2010-10-15

If the power supply is right then why would it work right on 15 volts but not on 12 volts.

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steveastrouk (author)Re-design2010-10-15

because the relay drive transistor isn't saturating, because its not driven well enough. The extra volts helps, but the relay drops out ?

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Jack A Lopez (author)Re-design2010-10-15

Hey, that's a good point. I misread the question before, and I thought he was using a 12 volt supply.

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user
Re-design (author)2010-10-15

What are the power requirements listed in the instructions?

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acakostic (author)Re-design2010-10-15

Thanks all for response

For power supply 10-15v. They recommended 12v and at least 300ma so I bought 12v 500ma. But with that power supply the relay doesn't work properly it constantly turns on/of. With the other one 15v 1.2a it works good. Any ideas?

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