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.
In this circuit, from a 1977 publication, we have the traditional version of a filter that rejects 1...
The integrated circuit used in this application is uncommon today. However, the basic...
This physical line servo control uses components that are not currently common. The circuit is from...