This circuit for frequencies of 20 to 2 kHz was obtained in English documentation from 1966. The transistor can be any general purpose and powered by batteries.
The operational amplifier used in this circuit is not common today, but it can be implemented with...
This circuit is used to test triacs. It can be connected in series with a resistive load such as...
In the figure we have the configuration of a transistor as a temperature sensor. The circuit is...