This library provides symbols for various vacuum (electron) tubes (or as the Brits call 'em, valves). It also contains generic symbols for different tube circuits.
Generally, symbols follow these rules:
- Plate/Anode is on the top
- Control grid is on the left
- Cathode is on the right
- Additional grids are on the right
If present, the heater is separated into a separate unit. Although this breaks KiCad library conventions, vacuum tube circuit diagrams will often have all the heaters in the same place, somewhere off to the side, in order to reduce clutter.
Each logical element of the tube is split into symbol units, even if they share some elements. For example, the 6AV6 tube contains a triode and two diodes with a shared cathode. It is structured into four units:
- Unit A - Triode
- Unit B - First diode
- Unit C - Second diode
- Unit D - Heater
Note that the KiCad 9.0 ERC does complain about duplicate cathode pins between Units A, B, C. It's possible to share a pin between all units, but that typically is not good enough for tube schematics, so for now, the error needs to manually supressed in the ERC.
Device_Vacuum_Tube provides generic vacuum tube symbols analogous to the
generic transistors in the standard Device library. Versions with heaters and
without heaters are provided. These symbols can and should be used as templates
for creating new symbols.
The naming pattern for these symbols is:
VT_<type>_[variation]_[heater]
For example:
VT_Pentode- Generic pentode, no heaterVT_Pentode_G3K- Generic pentode, G3 internally connected to K, no heaterVT_Triode_H- Generic triode, with heaterVT_Diode_F- Generic diode, directly heated cathode