I have a friend with arthritic hands who needed amplification for a mouth organ. Because she can't hold a normal microphone as well as the mouth organ I got a guitar piezo pickup to stick on the top of the mouth organ and fed it through an amplifier (see attached circuit).

Using a scope and a signal generator I have verified that the amplifier is operating normally and is putting out a significant signal. However, all attempts to get a reasonable volume from the piezo have failed miserably. I do get some sound when tapping the piezo which verifies the amplification path, connections etc but hopelessly insufficient level for practical use. A number of different guitar pick ups have produced the same result.

I'm now building an electret microphone on a small bracket for her, but I can't get out of my head the idea that the piezo should have worked.

Any thoughts gratefully accepted.

Cheers

Barrie Davis

 

What is your guitar piezo, does the function can be a buzzer, could you attach the picture?
And how is the mouth organ, does it like the brand of Butterfly?
Have you try to using a small Condenser Microphone, maybe using that could be better, just maybe, because I didn't see the details.

Try to remove the 0.1uf capacitor and try it again.

 

how was the piezo stuck on? if it were placed flat on the mouth organ, it night not have been able to vibrate properly. you might try mounting it to the edge with a couple of spots of rtv, so the center could viberate seperatly from the edges.