Light test (CB8789E)

This light-sensing probe was found in a 90s Popular Electronics. The circuit detects light sources by triggering a buzzer.

Signal injector (CB22158E)
This circuit was found in an English publication from 1989. The integrated circuit is an...
MW Experimental Radio (CB4517E)
This circuit was obtained from a 1964 magazine and has some interesting features such as the input...
Gain 10 Amplifier (CB25636E)
Using a general-purpose transistor this AC amplifier was found in the November 1993 issue of...