[SOLVED] Mic amp, very simple design. Help with gain

[zerodegreec]

Thanks everyone.

With the way the intercom is setup in our cars, there is no practical way to tie into the amp itself and or tie into the other mic and speaker. I am stuck with just the 3 wires going to the amp from my side.

 

[erikl]

kak's suggestion would be the right way.

Now is there a way to get the side tone without taping into the speaker B line? Somehow use my mic output (either before or after my pre-amp) through what ever black magic is needed and into my own speaker?

But if there's no way to access the "B" speaker(+) terminal, your a.m. black magic would be an external amplifier (plus its power supply: small battery) between your yellow mic(+) and green speaker(+), best with kak's 2-resistor + 1 poti solution to allow for volume adjustment.

For (a standard stereo plug), double plug adapters

are available, which directly connect all 3 electrical connections of the plug in parallel to the 2 female jacks. So you could insert your ZeroDegreeC part into one jack, and a custom-made amplifier (+ battery and volume control) into the other one.

 

[BradtheRad]

Yes, the stereo Y-plug mentioned by eriki looks most feasible.

If you adjust the additional amp carefully it will only need 1 transistor, powered by a 1.5V AAA or N cell.

Or if you need more voltage then a 3V lithium calculator/watch battery.