external sounder piezo

[keendiyer25]

hi there its the guy who got shocked by strobe or piezo transformer, hi sorry for the very late reply but im just curious to know how piezos work on an alarm sounder i understand they use a transformer and reverse polarity waveform or something but what voltage are these piezos i noticed that the voltage idicator lite up red, are these piezos transformers high voltage or are they a special transformers cheers

im just a bit confused how they work i think they put an electric current on the negative but after that im at loss any help would be great thanks

 

[ekmdgrf]

Hi. It looks like the shift and full stop keys on your keyboard have stopped working. You should have a look at getting a new one, as they're only a few quid and make your posts much more readable.

Piezo crystals change shape when a current is passed through them and vice-versa. I imagine to make a sounder you just need to attached one to a loudspeaker and switch it on and off at the required frequency to get the desired tone.

Alarm systems are generally 12V.

 

[Taylortwocities]

Yes, it does look as though all of the punctuation keys on his keyboard just don't work.

I have seen this problem before, usually with anybody under the age of 20.

 

[viewer]

Pity, another neurone and he could have been a geranium.

 

[Taylortwocities]

It is nice to see that sensitivity is still alive and well and living in Scotland.

I wish I knew the answer to his question though. Though its been much more fun to wind him up from Toryland.

Oh no! Suppose the independence vote says yes by only one paper. You'll all blame me for making the Salmon King