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 sensor for this circuit, found in a 1968 magazine is a common LDR. The diode is for general use...
This circuit was obtained from Motorola documentation from 1969. The setting applies to other...
This circuit is from 1968 and consists of an amplifier for turntable of the time. The CA3020 was...