Photocardiograph (CB21738E)

We found this circuit in a 1969 Popular Electronics. It measures the heartbeat by changing the transparency of the finger.

6 or 12 V x 1 A Regulated Power Supply (CB1168E )
This is the traditional configuration of a 6 or 12 V source with 7806 or 7812 integrated circuits, for a...
Driver for piezoelectric motor (CB7998E)
Found in an Electronic Design from the 90s, this circuit uses high voltage operationals of the...
Reaper (CB21928E)
This reaper or signal limiter can be used to convert a sinusoidal signal into a square. The...