We found this circuit in the Radio Electronics Handbook magazine special edition of 1992. The circuit uses an optocoupler as an electronic potentiometer.
This circuit was found in a 90s Wels' Think Tank. The frequency depends on C2 and R3. The handset...
We found this circuit in a 1981 publication. We applied an audio signal, for example, a music...
This circuit was suggested by General Electric in 1969 documentation. It provides a maximum output of...