This circuit was found in Motorola documentation from 1969. The transistors are from that time. The pulses are 200 ns with 500 mA. Observe the high supply 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,...