Opto control for triac (CB20552E)

Found a documentation for PC from 1992, this circuit is indicated for the English power grid of 240 V.

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...