Simple transconductance amp powered by 48VDC@2mA?

AnalogKid said:

If you don't want to hand solder a circuit, Adafruit has microphone+preamp modules, one with AGC and one without. You can remove their mic and run (short) wires to the TRRS jack.

Electret Microphone Amplifier - MAX4466 with Adjustable Gain

Add an ear to your project with this well-designed electret microphone amplifier. This fully assembled and tested board comes with a 20-20KHz electret microphone soldered on. For the ...

www.adafruit.com

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That's good to know, but personally I find most of the enjoyment is found in understanding the principles and building a solution, albeit needing a push in the right direction from those with far more expertise! Thank you for the tip, I might fall back on the Adafruit options if I need to expand the number of headsets in future.

Well, I've made one of the emitter follower buffers, and it works just fine

Follow-up question: where in this circuit can I fit a normally-open single-pole switch so that I can have a push-to-talk function, with minimal audible click?



I thought that it could go between either of the DC blocking 0.47uF capacitors and their adjacent 100k resistors, as marked in blue on the diagram? That side should not have any DC offset to cause switching clicks, no? And by leaving the Zener reverse biased and the electret powered, there wouldn't be any 'power up' clicks either, right?!

Or, would it be better to mute the electret by interrupting the 12V either side of R3, so that when you push-to-talk the 12V is connected to bias the electret?