HP nixie tube module information needed

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue May 20 19:32:54 2003

> Dwight,
>
> The circuit board portion is easy, but the bit inside of the black
> box is a bit more complex. While I originally thought that it might be
> an integral HV supply of some sort, I now have additional information
> which says otherwise. Interestingly enough, that info originated from
> Tony Duel. Here it is:

Yes, it is me :-)

The block is not that complex. Inside there are 8 neons. From the top,
they are : C, C/, B/, B, D, D/, A, A/ (according to the manual). The neon
wires are soldered to the PCB. On top of the block is the thick-film LDR
array, and on tom of that is a resistor network of 10 270k resistors. The
top wire of that goes to the +20V rail, the wires on the left go to the
nixie cathodes (there's a 270k resistor from each cathode to +20V). The
LDRs also connect to the cathodes. The bottom wire from the resistor
network is not used, but the pin it's connected to is the common of the
LDR array, and goes to -130V.

There's a good theory-of-operation section in the 5245 manual, BTW. You
want to try to get a copy of this.

-tony
Received on Tue May 20 2003 - 19:32:54 BST