We found this circuit in a Radio Electronics from December 1963. The circuit combines valves and transistors and has a high input resistance. The circuit is powered by two batteries.
This circuit for link or alarm was found in the Encyclopedia of Electronic Circuits Volume 5 of...
This circuit is from a Popular Electronics of the 90's. Any power MOSFET can be used. The circuit...
This circuit extends the scale of a milliammeter. We found it in a documentation from the 60's. The...