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.
The oscillator shown in the figure generates a 1 kHz tone that is reproduced on the speaker with...
In the figure we have the photo-conductive way of using a photocell to control a small motor with...
This circuit was found in the June 1991 issue of Radio Electronics magazine. The circuit uses two...