Found in the February 1990 Radio Electronics issue, this sophisticated 100 MHz probe uses a period display module. The circuit has an external power supply.
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,...