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.
This circuit from an old documentation includes the power supply for the 117 V power grid. It can be...
The frequency of this circuit is approximately 1 Hz. Whenever the output is at low level, the LED...
This circuit has been found in an old documentation and therefore uses a lamp as an indicator. In a...