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.
In the figure we have the basic configuration of an operational amplifier for audio signals. The...
This General Electric circuit produces pulses of light only when light stops shining on the...
Found in an Electronic Design of 1964 this circuit has a control for the frequency and another for the...