Found in 1980s Electronics Design, this circuit covers 4 decades of frequencies with a unique control. A multi-turn trimpot is used for fine adjustment. The frequency range depends on C1.
This circuit produces a 300 Hz signal from a 10V input. The circuit is from a 60's documentation, making use...
This is a circuit from the time when some still called the transistor a crystal triode. It...
We found this circuit in a 1975 circuit manual. The operational amplifier is of the old type and...