Found in older Signetics documentation, this circuit generates signals from 30 Hz to 25 kHz. Operational amplifiers are from the time, as is the matching pair of transistors.
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
Obtained in a 1968 Electronics World, this circuit uses transistors from the time and the sensor...
The basis of this circuit is a CA3130 operational amplifier. The transistor can be BC548, and the...