This voltage-controlled potentiometer using an LDR was found in an English documentation. LDR is common and LED of any type.
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....