This circuit can be used with 3 receivers and is intended for low frequencies (medium wave range). We found it in the September 1995 Electronics Now magazine.
This is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time....
This traditional crystal radio circuit, but which has a modern version with diode, was found in an...
This headphone amplifier using a pickup coil can be used as an extension for devices such as TVs,...