Found in General Electric documentation from 1967, this circuit uses an unusual PUT today. The frequency depends on C1.
Found in an EDN from the 80's, this circuit makes use of an operational one of the time. The...
This circuit can either directly supply a piezoelectric transducer (BZ) or a stage with a...
Only for reference this is a circuito f a commercial receiver of the year 1958. The circuit uses...