Silent alarm (CB22471E)

This circuit is from a Popular Electronics from 1992. The circuit powers an LED when triggered.

Simple Photometer (CB14445E)
The sensor for this circuit, found in a 1968 magazine is a common LDR. The diode is for general use...
Comparator with an operational (CB6501E)
This circuit was obtained from Motorola documentation from 1969. The setting applies to other...
Play-Records from the 60s with the CA3020 (CB18500E)
This circuit is from 1968 and consists of an amplifier for turntable of the time. The CA3020 was...