Amplifier stage with the T411E (T411E)

The pentode tube used in this circuit has 1.5 V filament. The circuit is a voltage amplifier with the 1U5 tube.

Analog Multiplier (CB7930E)
Found in a 1968 EEE, this circuit accepts frequencies from 1 to 1000 Hz and control voltages from 0.1 to...
1 W LM386 Amplifier (CB17022E)
This circuit has appeared several times on this site in different applications. This is from 1997...
Compator with hysteresis (CB5079E)
This setting appears other times in this section from other sources. This is from an 80's American...