This optically coupled circuit was found in the February 1968 Radio Electronics magazine. The circuit uses an LDR in modulation. Transistors are types of the time.
We found this code switch circuit in the January 1999 Electronics Now magazine. Some of the...
We found this circuit for musical instruments in the March 1992 Radio Electronics magazine. The...
This circuit was found in documentation from 1977. Its purpose is to diode-switch the frequency of a VFO....