Found in the May 1971 Radio Electronics magazine, this is the circuit for a commercial high-impedance instrument. The circuit uses 4 transistors and is powered by 2 9 V batteries.
This circuit automatically switches the mains voltage to a transformer. The circuit is from 1997...
This different circuit was found in a Radio Electronics from August 1965. It works with a voltage of...
This step-down converter with 10 to 60 V input produces a 5 V output with a maximum current of 5...