Light test (CB8789E)

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

Operational Transistor Control (CB12177E)
With this circuit it is possible to control an operational amplifier so that it switches an input...
40W Transistorized Amplifier (CB11574E)
This circuit consists of a traditional amplifier version with complementary output using BD series...
Microphone Preamp (CB6036E)
This circuit was obtained from a Texas Instruments 1985 document. The circuit is powered by 1.5 V...