IEEE 315-1975 (R1988) pdf free.Graphic Symbols for Electrical and Electronics Diagrams.
Ifnew symbols are necessary, they should be formed where possible from component symbols.For example, seeDYNODE (item 7.1.4.1), which combines the anode and photocathode conventions.
A connection to anode, dynode, pool cathode, photocathode, deflecting electrode, composite anode-photocathode, and composite anode-cold cathode shall be to the center of that symbol. Connection to any otherelectrode may be shown at either end or both ends of the electrode symbol.
A diagram for a tube having more than one heater or filament shall show only one heater or filament symbol/unless they have entirely separate connections. If a heater or filament tap is made, either brought out to a terminal orinternally connected to another element, it shall be connected at the vertex of the symbol, regardless of the actualdivision of voltage across the heater or filament.
Standard symbols, such as the inclined arrow for tunability and connecting dotted lines for ganged components,may be added to a tube symbol to extend the meaning of the tube symbol, provided such added feature or componentis integral with the tube.
Electric components, such as resistors, capacitors, or inductors, which are integral parts of the tube and areimportant to its functional operation, shall be shown in the standard manner.Multiple equipotential cathodes that are directly connected inside the tube shall be shown as a single cathode.A tube having two or more grids tied internally shall be shown with symbols for each grid, except when the gridsare adjacent in the tube structure.Thus, the diagram for a twin pentode having a common screen-grid connection foreach section and for a converter tube having the No. 3 and No. 5 grids connected internally would show separatesymbols for each grid. A triode where the control grid is physically in the form of two grid windings, however, wouldshow only one grid.A tube having a grid adjacent to a plate but internally connected to the plate to form a portion of it shall be shownas having a plate only.IEEE 315 pdf download.