This circuit uses an MW radio tuned to around 540 kHz to detect atmospheric signals, for example, from an approaching storm. The circuit was taken from a Popular Electronics from the 90s.
This basic oscillator with tunnel diode generates a 100 kHz signal with 1 uW output power. The...
This amplifier for medium or high impedance magnetic headsets (above 200 ohms) was found in an...
This circuit provides precise signals of three frequencies, using CMOS technology. The integrated...