Found in a Popular Electronics from the 90's, this circuit is used to recognize the frequency of a modulated infrared signal. The LM567 circuit must not be supplied with voltages above 9 V.
We found this circuit in an old publication (1977) using common transistors at the time and now...
This circuit uses an operational that is not currently common. We found it in an old American...
Bis This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine. The...