Touch controlled voltage source (CB22141E)

We found this circuit in an old English documentation. Transistors support modern equivalents.

3 to 35 V with 4 A power supply (CB4332E)
We found this source with the CI 723, common at the time, in a 1989 paper. Power transistors must be...
Vox CA3055 (CB24260E)
This old voice circuit suitable for telephones of the time was found in a Radio Electronics from...
CMOS Frequency Meter Up to 12 MHz (CB13726E)
We found this frequency meter circuit in a 1974 documentation. The circuit is powered by 12 V and...