Filament source (T398E)

Despite being transistorized, this is a constant current source circuit for 1 V valve filaments such as the 1H4 tube.

Variable Source (CB18169E)
This source, from a 1982 documentation, uses a triac to control the power and voltage applied to...
6 W Amplifier TDA2613 (CB15725E)
The amplifier presented is ideal for use in small monophonic sound systems, radios or televisions powered...
Remote volume control (CB23927E)
This wired control circuit serves both volume and balance between channels. We found it in Radio...