This sophisticated remote field strength meter circuit was found in a 73 magazine for radio amateurs from the1990s. The circuit measures signals in the 1650 kHz range.
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...