This simple audio signal tracer or follower can be made with a BC548 instead of the original transistor. The output is made in a small crystal phone. The power can be from 5 to 9V.
The project is from a 1992 publication, but totally current by the components it uses. The LEDs...
This circuit was found in Radio Electronics from the 90s. The transistor is for general use. The...
This circuit is suitable for testing motor starting capacitors. Capacitors from 2 to 8 uF are...