This circuit, which uses a quadruple comparator, was found in old American documentation. The response curve is shown next to the diagram and can be adjusted in the trimpots.
The circuit is from an 80's publication, but the components are current, only special type diodes...
This circuit was found in a 1965 Electronic Design. Transistor Q2 must be load dependent. The circuit...
This circuit was obtained from an 80's amateur radio documentation. The integrated circuit is a...