This circuit consists of an improved version of the CIR5892, using two transistors and adjusting the operating point. The transistors can be the BC548.
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,...