This circuit, which can be used as a shield or in other applications, can be found elsewhere on this website. The supply must be made with 5 V.
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,...