This circuit is from a technical documentation on the National Semiconductor LM3909. The tripping transformer has a 1:1 turn ratio and the circuit is powered with 5V.
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,...