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 was obtained in a 1965 American magazine translation. The photocell can be the type...
This circuit consists of a mixer with some additional features, having been found in a 1990...
This digital instrument input circuit was found in the September 1989 issue of Radio Electronics...