This circuit was found in the February 1990 issue of Radio Electronics magazine. The gain is given by the capacitors according to the table next to the diagram.
This circuit was found in a 90s Hands-on Electronics. The transistor can be a BC548. What it does...
This circuit separates the bass from the treble in an audio signal. The circuit is from a Hands On...
The frequency of the signal produced by this circuit depends on the temperature of the diode used...