Mini Megaphone (CB8952E)

Found in Popular Electronics' 90s, this small megaphone is based on LM386. The circuit uses a high impedance microphone.

Automotive Tachometer (CB13706E)
This circuit was obtained in a 1975 documentation. It is intended for old vehicles that still use...
Transistor gain test (CB20734E)
With this circuit it is possible to select transistors and their compliant test. Or circuit...
Variable Power Supply with Selector (CB24588E)
This power supply circuit with selectable voltages was found in the June 1979 issue of Radio...