Voltage amplifier with the 37 tube (T392E)

Found in a modern design book with tubes, this stage with the triode 37 has a plate current of 3.7 mA.

Relay Drive AC Stage (CB12182E)
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
Visually Impaired Electronic Guide (CB18123E)
With this circuit the visually impaired can easily locate important places inside the house, such...
Schmitt trigger (CB21475E)
In the figure we have the way to use the transistors of an old-paired pair as a trigger circuit. The...