We found this cable tester in a Popular Electronics from the 90s. The circuit uses a connector according to the cable to be tested. Adaptations can be made for different types of cables.
This circuit can function as an output shield for microcontrollers, being compatible with TTL...
This circuit is from a 1979 publication, using displays of 7 segments of common cathode. The...
This circuit is from an English publication of 1982. The bipolar transistor can be a BC548 and the...