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.
This circuit is from a 1996 publication, but it can be assembled with several equivalent...
This conventional Hartley oscillator circuit with an audio output transformer was found in a...
The oscillator in the figure has its frequency determined by the crystal. The indicated value is...