Diode Tester (CB22137E)

This diode tester was found in an English publication from the 1980s. Transistors are general-purpose types of the time.

Plant soil heater (CB7964E)
This circuit was found in a 90’s 303 Circuits. The components are from the period and the heating...
Biofeedback with the 555 IC (CB10959E)
This circuit was found in a 1987 magazine. It consists of an oscillator controlled by the...
1 W amplifier (CB8948E)
This circuit was obtained in a 90s American documentation. The integrated circuit used is uncommon...