Found in a Popular Electronics from the 90's, this circuit is used to indicate the operation of telephones of the time. The circuit is TTL.
This optically coupled circuit was found in the February 1968 Radio Electronics magazine. The...
We found this circuit in the April 1978 issue of Radio Electronics magazine. The power supply must...
This circuit supports several sets of coils and can oscillate from 1 to 44 MHz. The transistor is an old...