We found this circuit in a 1966 US documentation. It simulates a variable capacitor that can vary capacitance from 1,000 to 1. Transistors are general purpose types.
In the figure we have a circuit suggested by National Semiconductor, using an operational...
Tone controls for audio applications can also be considered filters that must attenuate certain...
This circuit was found in an Argentine publication from 1973. It uses a common AM coil (50 + 50...