Found in an American 1980s documentation, this circuit compares signals from two TTL sources, providing an output that depends on the frequency difference. The circuit can be used as a shield.
I found this circuit in an English magazine from July 1982. The circuit is still viable as all...
The circuit is from the 1990 Motorola Linear Databook. The circuit can be implemented with other...
This indicator makes use of an LM339 voltage comparator circuit that contains 4 internal...