We have many tube tester circuits in this section. This one came out on a Radio Electronics from 1949 and has a very elaborate configuration with toggle switches.
Suggested by Siliconix in documentation from the 90s, this amplifier has its gain digitally...
January 2017 - Pulse Electronics ER11 transformers with high insulation can be obtained from...
This circuit is from an American 80's documentation. The circuit indicates when the voltage of a 9 V...