This circuit incorporates the passive control of the previous circuit and was also found in the March 1995 Electronics Now magazine. The power supply must be symmetrical.
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,...