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.

Transistor Metronome (CB11939E)
This configuration has already been given in several articles and circuits on this website and...
High impedance comparator (CB5088E)
This circuit is from a Harris Semiconductor datasheet from the 80s. However the circuit can be...
Fast TTL Probe (CB1462E )
We found this logic level tester in a 1976 documentation. The circuit is powered by the voltage of the...