|Aug11-12, 04:57 AM||#1|
Personal Voice Amplifier Background Hum Trouble
Long-time lurker, first post, here goes.
So I'm working on a personal voice amplifier for a face mask. I have the dynamic mic element (datasheet), which feeds into a 3v class A preamp, through a 100k audio taper pot, to a 6v lm386 amp with the gain set for 200.
The problem is that there is a very loud buzz present while using the preamp, which is not present while using on the lm386 amp. However, if I put my finger across the pins for the potentiometer the sound clears and be comes noticeably louder and operates correctly.
The only difference between my circuit and the one schematic I linked to is that I substituted polyester caps in place of the ceramic, I didn't think it would make much difference, but I could be wrong.
Schematics available on demand.
I'm at my wits end, any help would be appreciated!
|Aug11-12, 12:38 PM||#2|
You need to post the schematic and preferably a picture of your circuit. It is hard get what you circuit is by reading.
|Aug14-12, 02:57 AM||#3|
Examine the audio on an oscilloscope and determine its frequency, is it identical with your mains frequency? Then probably your finger is performing the earthing function.
|amplifier, audio, noise, preamplifier|
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