This two-port configuration of the 4001 was found in the April 1988 issue of Radio Electronics magazine. The timings are given by R1 and C1 as a function of the desired behavior of the circuit.
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,...