Maybe because it's Monday.

I'd like octal PNP driver to switch up to -40V for VFD from PIC.

Like a ULN2803, except PNP. Run common off +5V, and collectors all to=20
-24V via 100K ohm.

Anyone know of a cheap easily available part?

I don't see a pnp version of a ULN2803, I can just use 24 BC557 or=20
2N3906 PNP etc...

Just thinking...
Run filament + and - off AC at -15V (need 3.5V AC "centre tapped" at=20
just under 50mA, put 6.8V zeners on both ends of filament and drive both=20
ends via capacitors  with anti-phase pulses from 5V to give 3.5V average?)
The Anodes / Grids need to be pulled down by 100k Ohms to about 4.5V=20
below filament. If filament is "centre tapped" AC ish drive, then -V=20
needs to be about 7V below filament, 6.8V zeners. Max current is about=20
50mA on the  -24V (one digit on and all segments on) I think as Anode=20
(segment) current only flows in lit digit (one grid on).  So 700mW=20
wasted in Zeners... Maybe two boost inverters, one for filament /=20
cathode and one that's 7v more negative  for 100k pull downs would save=20
500mW to 600mW


--=20
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