12V x 10A power supply (CB21775E)

This power supply is from a 1977 documentation. The transformers have 11 V secondary with 10 A.

Tunable notch filter (CB7404E)
We found this circuit in an English publication from the 1980s. The circuit uses current...
Telephone Relay (CB15524E)
The circuit shown in the figure can be useful in cases where a common telephone extension is used....
Proximity Switch (CB13489E)
We found this circuit in an American documentation from 1977. The circuit must not be powered by a...