This circuit is from a 1975 RCA tube manual. It appears elsewhere on the site. R5 depends on the voltage of the amplifier with which it is used and can be changed.
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...