Greetings...

I've wired an hearing aid circuit found on internet. it works well except annoying high-pitch sound at the ear phone. when not high-pitch sound heard it works quite well..

How can i eliminate this unwanted high-pitch sound...

any suggestion please...

thanks,

 

It sounds like it could be unstable and oscillating, this could be down to either poor circuit design, or poor construction.

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It sounds like it could be unstable and oscillating, this could be down to either poor circuit design, or poor construction.[/quote]

So, you mean i should try another circuit or reconstruct it by replacing the component with more spacing ( i tried to put the component as close as possible for making it real small and didn't pay attention for oscillating)

anyway thanks for the quote.

Now at least i have an idea how to solve the problem..

Thanks Nigel....

 

Hi Sarak,
I think that the sound is accoustic feedback. This happens when the microphone can hear the earphone, is amplified, makes more sound and is heard and amplified again and again. So the sound goes around and around. When it does work well, then the microphone cannot hear the earphone very much maybe because the earphone has a better fit into the ear canal (and therefore the sound cannot escape to the microphone), or then the gain is not too much.