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 configuration of this circuit was suggested by an old English publication that comes to...
Using comparators, this circuit can be used in a measurement bridge. The balance indication is...
Found in a 1999 documentation, this circuit makes use of a power germanium transistor and a...