Nixietube why use PNP to drive?
The LED digital tube consists of a plurality of light-emitting diodes packaged together to form a "8" type device, and the leads are already connected internally to draw only their respective strokes, common electrodes. The nixie tube is actually made up of seven light-emitting tubes, consisting of 8 figures, plus 8 decimal points. These segments are represented by letters a, B, C, D, e, F, G, and dp.
In general, in addition to the public side, you are digital tubes of the same paragraph lines are parallel, each segment is also driven by the triode or IC to drive.
High voltage diode anode digital tube of the terminal in the drive level through the transistor, which is connected to the high voltage, so the current flowing from the other end of the diode. The 7 diodes must be connected to the collector of the triode to meet the needs of amplification. If the NPN tube is used, it can only be connected to the transmitter level, which does not meet the requirements.
