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.

Low Pass Filter with 741 (CB1454E)
We found this circuit in a documentation on active filters from 1977. The gain of this circuit is...
Simple Touch Switch (CB16945E)
The touch sensor of this circuit consists of a single plate that must be touched to obtain an...
Coaxial Cable Amplifier LM6181 (CB14411E)
The integrated circuit used in this project is not common today, as it was obtained in the Linear...