Pentode voltage amplifier (T407E)

This circuit uses a 77 tube as a voltage amplifier obtaining gains of approximately 100 times. The circuit is from modern documentation on tubes.

Battery Charger (CB4388E)
This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent...
5 Voltage Level Indicator (CB4892E)
This circuit is based on an uncommon Texas component today, as found in an American 1980s...
Coils For Qi Chargers
April 2017 - Mouser Electronics owns standard Qi wireless charging coils for a power range of up...