# Electret Mic signal amplification without DC offset

I'm working on a small audio project and I need a circuit that does the following: take a signal from an electret mic, rectify the signal, amplify it, and remove the DC offset. I have tried many circuit designs but they are not working fine with me (too much noise and with DC offset). Should I mention that the electret mic's resistant is approximately 2.8 kΩ. Thanks in advance. any help will be appreciated :)

• Maybe you should share with us the "many circuit designs" you have tried - this would save folk wasting their time on lost causes that you would inevitably reject. Alternatively, sit back, pay attention and if someone proposes a circuit (you have rejected) (and others agree it should work) try and learn why it didn't originally work for you. Firstly though, what are you trying to achieve with the rectification and do you mean full-wave or half wave? Mar 8 '14 at 20:43
• A lot of this depends on the details of whether it's supposed to be single supply etc. Andy's suggestion is perfectly reasonable. One key take-away from his answer is that you should block the DC offset from the electret before rectifying. Mar 8 '14 at 21:16
• @spehro I did say that in my answer for input and output. Mar 8 '14 at 21:57
• @Andyaka He should accept your answer. Mar 8 '14 at 22:14
• @SpehroPefhany - I don't think he listens too well dude LOL!!! Mar 8 '14 at 23:06

This is what wiki says: -

This will work fine providing you AC couple your microphone to the input and AC couple the output. Simple series capacitance will do the decoupling of the DC signal.

PS it's only half wave rectification shown above.

This is a full wave circuit

• ok I tried this circuit: link , the circuit's amplification is not high and with high noise yet it removes the DC offset. link has an excellent amplification yet it does not rectify or remove the DC offset. Mar 8 '14 at 21:19
• sorry dude but these circuits work. They are standard circuits and if they didn't work for you then you did something wrong Mar 8 '14 at 21:32
• any advices on how to optimize the second circuit, I mean how to fully rectify it and remove the DC offset? Excuse me but I'm new to this. thanks in advance :) Mar 8 '14 at 21:45
• ac coupling the input and the output gets rid of unwelcome offsets. Mar 8 '14 at 21:55
• sorry I'm only commenting on circuits in my answer dude. Mar 8 '14 at 21:58