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.
The integrated circuit used in this 80's application is very hard to find today. The circuit is of an...
This circuit was found in a 1970 US publication. Transistors are still common and the circuit can be...
The circuit shown in the figure can be used to detect vibrations or to provide amplified acoustic...