This circuit allows the use of an electret microphone with a 1.5 V source. We found it in the Encyclopedia of Electronic Circuits volume 5 from 1995.
We found this circuit in the Radio Electronics magazine of January 1986. The frequency is given by the...
This circuit has a type of bias called "virtual earth" providing good gain, given by R2. The...
The figure shows how to convert a rectangular signal into a triangular signal using an integrator. The...