Mini solar organ (CB20506E)

This circuit was found in an old documentation and can be powered by a solar panel. The touch resistor is a nichrome wire.

Automatic headlight shutdown (CB7260E)
This circuit for automotive use was found in American documentation from the 90s. The circuit uses...
Transistor Tester (CB14958E)
This type of circuit is traditional and has been published several times in different forms and...
48 to 190 MHz Receiver (CB18521E)
This VHF receptor was found in a Japanese publication from the 1960s. The original transistors can be...