This 1.5W tube amplifier was found in an American documentation from 1947. It is a direct rectification circuit without the need for a power transformer.
This circuit is from the 1994 Linear Applications Handbook. The operational circuit can be...
This circuit is suggested by National Semiconductor (now Texas) in an old manual. The circuit...
With this circuit, found in a 80s Popular Electronics, it is possible to use two ordinary phones in a...