This circuit was found in a 90s RF Design. It is an oscillator that can reach 800 MHz, with the frequency controlled by an input voltage.
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,...