This circuit makes use of components from the time it was published. The TCA151 is not a common component today. The circuit generates 10 to 10 kHz signals.
This circuit is from an English publication from 1978, but it can be assembled with BC548 for TR2...
This simple voltage regulator with FET was found in American documentation from the 1980s....
This circuit was used to regulate the speed of small DC motors of cassette recorders. However, if the...