This circuit was found in a 1967 Electronics World. Transistor Q1 can be a TIP321 and Q2 can be a BC558. The indicator lamp is optional.
This is the traditional configuration of an unregulated bridge rectified power source. The circuit...
In the figure we have a circuit that produces interval pulses, reproduced in the piezoelectric...
Found in American documentation from the 90s, this circuit passes frequencies above 1 kHz. The...