This circuit is intended to recover a very weak signal at a receiver, for example, a CW signal or a tone signal. The circuit is from a Popular Electronics from the 90s.
This two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The...
Suggested by Radio Electronics from the 90s, this circuit is suitable for NiCAd batteries with a...
082E) We started with a simple Hartley oscillator circuit using a bipolar transistor that can...