This is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time. The circuit is from the 90's, not being given the power supply.
This circuit is from a Radio Electronics from April 1965. It uses an incandescent lamp, and the...
This circuit was found in a 1968’s publication and uses germanium transistors. The characteristic...
This is a single IC voltage regulator that can acts in the range from 1.2 to 20 V. Output currewnt is up to...