Light test (CB8789E)

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

Negative Regulator Power Supply (CB13065E)
In the same way that we can regulate the voltage in the positive branch of the circuit, we can...
Visible optical link for RS232 (CB21602E)
Based on the MC1488 or MC1489 operational amplifiers, this circuit has a 5000V isolation driving a...
3-Transistor Radio (CB21641E)
Found in the July 1968 Supertena Bulletin of a Popular Electronics, this receiver makes use of the...