Electromechanical Counter (CB21682E)

This photoelectric circuit from a 1960 publication uses a 6.3 V electromechanical counter, common at the time.

RIAA 3-Transistor Equalizer (CB1371E)
This circuit was found in a Japanese documentation of the 70's. It uses transistors of the era and is...
Benchtop power supply (CB22527E)
This benchtop AC and DC power source was published in the December 1957 Radio Electronics...
Capacitance Multiplier (CB14089E)
The configuration already explored in our Circuit Bench section is from the National...