This semi-proportional temperature control was found in old American documentation. The components are from the period and the maximum power of 2.4 kW.
This lie detector was obtained in a Japanese publication in 1967. The component with a different symbol...
This old amplifier uses germanium transistors from the time. The circuit is from a Mullard...
This circuit is from an American publication from the 60's. The transistors are made of germanium. It...