Lie Detector (T1534E)

This circuit was found in a Popular Electronics from December 1956. Power is provided by batteries.

Flat Response Low Pass Filter (CB9770E)
Found in American documentation from the 90s, this circuit can be applied to other operational ones. We...
Darlington Photo Trigger with Reset (CB14659E)
We found this circuit in the Texas Instruments opto-electronics manual. The button resets and the...
Field Strength Meter (CB13267E)
We found this circuit in an old American publication. The transistors can be BC558 and diode 1N34....