This circuit uses a 7-segment display to indicate the logic level of a test circuit. The power supply is made with 5 V that can come from the analyzed circuit itself.
This circuit was found in a 1976 NASA manual, making use of components of the time. The transistor...
The circuit that gave rise to this configuration is from 1978. In the original publication are...
We find this circuit in documentation from the 1980s. The triac and diac are of conventional types...