This protection circuit for symmetrical 28 V power sources was found in a 1968 EEE documentation. The circuit can be adapted to use modern equivalent components.
This circuit was found in an English publication from 1991. As in that country the power grid is...
This circuit tests crystals up to a few megahertz with ease. The circuit is from a 1977...
This circuit is from an American documentation from 1976. The FET can be the BF245 or MPF102 and...