This is a field strength meter found in an 80's Hands On. The circuit operates at frequencies up to 500 MHz and has a buzzer as its indicator. Can be used as a detector for spy transmitters.
Waking up to a loud and clear sound from an audio oscillator, after up to 5 hours of sleep, or...
This circuit was found in a publication from the 90s. The circuit can be assembled with modern...
This conventional oscillator with the 741 can be precisely adjusted to produce a 400 Hz signal. The...