We found this circuit in a 1965 General Electric manual. The components are from the period. Time resistors and capacitors can be changed.
Using the 555 and 7400 this circuit was found in the September 1977 Radio Electronics magazine. The...
This sensitive continuity test uses two transistors and has a common LED as indicator. The input...
This circuit appeared in a noverber 1962s Practical Electronics. The magazine is no more, but the...