We found this circuit in an American documentation from the 80s. The integrated circuits are operational amplifiers of the time. We can test modern comparators like the LM339.
The LM380 is not a modern component and in some cases not easy to find. But if you have one you...
This variable timing circuit was found in 1964 General Electric documentation. Circuit uses PUTs...
We found this circuit in the August 1994 issue of Electronics Now magazine. The circuit is based on...