Found in an Electronic Design from the 80's, this circuit monitors a three-phase line, activating a relay when one of the phases is missing.
I got this circuit from an English magazine from 1977. It can still be easily assembled, as the...
Found in documentation from the 1990s, this circuit supports equivalent transistors. The range is on...
We found this circuit in a 1972 RCA technical documentation. The comparator can be any type and C1...