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.

Adjustable Constant Current Source (CB6621E)
This constant current source for high voltage loads was obtained from a 1967 General Electric...
Balanced Modulator with Transistors (CB4237E)
Found in a 1980s telecommunications documentation, this balanced modulator circuit uses...
Active Band Pass Filter (CB6247E)
This circuit was found in Texas Instruments documentation from the 1980s. The circuit has a Q less...