This simple logic level tester was found in Radio Electronics from the 90s. The inverters are of the 4009 type and the power comes from the circuit being analyzed.
This frequency divider by 10 uses discrete components only. Modern equivalent components can be used as...
Found in an article in the August 1971 Radio Electronics magazine, this circuit supports sensitive...
We found this circuit in a 1972 RCA technical documentation. The comparator can be any type and C1...