The LM3909 tone generator integrated circuit of this application is uncommon nowadays. The circuit can operate on a single battery and is very sensitive.
This circuit is from a 1966 General Electric documentation. The circuit applies to sensitive SCRs for...
In the figure a circuit that is the basic application of NE567 for the detection of a tone applied to...
Found in old documentation, this circuit is the receiver for the previous circuit. Components are...