We found this circuit in the Linear Applications Handbook by National Semiconductor. It uses the LM3900, an operational transconductance amplifier as a base. Q1 can be a 2N2222 or similar.
This circuit was found in old documentation. The components can be replaced by modern ones. The...
This transistor circuit consists of a well-known bass and treble control configuration. The...
With the circuit shown, you can have a fast response with a Darlington configuration. The circuit is...