Divergence Meter - ZPUA UBZ-1 Relay & Contactor Tester

An unusual digital test equipment from the '70s/'80s Poland. Really well made, and just look at all those LC-513 goodness! Reverse-engineered by yours truly, and now I'm walking you through its internals. It's not the only episode I'll have about it, because I haven't demonstrated it on an actual relay - but there'll be more. Including some additional use cases like measuring the retraction time of a relay being switched off. 0:00 Intro 2:00 Meter Outside 5:25 Taking It Apart 6:30 Nixies and Connections 7:15 Counters and BCD Decoders/Drivers (Keri Out!) 8:40 Control Logic 10:18 Isostat Switches 11:30 Relay Control Part - Two SCRs 13:15 Power Supply 14:23 Reverse-Engineering and Schematics 15:00 Counter/Decoder/Display Part and Reset Logic 18:00 Oscillator and Frequency Dividers 19:12 Contact Latching 23:40 Start/Stop and Solenoid Control Logic 26:47 On-Off SCR Relay Control Circuit 28:38 Power Supply Circuit 30:05 Quick Demo 32:20 Afterword A bit perplexed by those flip-flops for sur