Sperry SP-425-08 Display - Datasheet?

Curious Marc curiousmarc3 at gmail.com
Tue Jan 7 23:55:27 CST 2020


I got the schematics of the driver circuitry from the HP 59304A documentation. You should be able to replicate it. Will send you in separate email.



From: cctalk <cctalk-bounces at classiccmp.org> on behalf of "cctalk at classiccmp.org" <cctalk at classiccmp.org>
Reply-To: Anders Nelson <anders.k.nelson at gmail.com>, "cctalk at classiccmp.org" <cctalk at classiccmp.org>
Date: Wednesday, January 1, 2020 at 6:15 PM
To: "cctalk at classiccmp.org" <cctalk at classiccmp.org>
Subject: Re: Sperry SP-425-08 Display - Datasheet?


Wow, thanks for all the info! I'd love to see examples of driving circuitry

if it's not too much trouble. I've made PCBs and such before so aside from

potentially jolting myself I'm up to the challenge.


Anything I produce (code, schematics/PCBs) will be posted to my blog as

open-source material.


Thanks again,




On Wed, Jan 1, 2020, 8:34 PM Brent Hilpert via cctalk <cctalk at classiccmp.org>



On 2020-Jan-01, at 2:42 PM, Anders Nelson via cctalk wrote:

> I snagged one of these Nixie-like displays (from a calculator I assume)


> I'd like to light it up. Does anyone know where I might find the


> for it? Google hasn't turned up anything.


> https://www.ebay.com/itm/264110638970


> Any help is appreciated!



7-segment multiplexed multi-digit gas-discharge display.


Those Sperry types weren't very prevalent, I'm not surprised you haven't

found a datasheet.


I'm being a little presumptuous in specifying gas-disharge, it certainly

appears to be, but the ebay pics are a little small.


There was another series of GD displays from Sperry, and another from

Beckman, which were more prevalent.


Assuming it is GD:


I have an example of one that appears to be of similar construction to

yours in this calculator:


Given yours says made in Japan, I wonder if they be from the same OEM.

I can send the schematic if you wish, for an example of drive circuitry.

It needs a little reformatting and conversion to pdf first, so let me know

if interested.


I have other calculators and schematics using the Beckman displays

(7-segment, multiplexed, multi-digit, gas-discharge).

They could also be comparitive examples for drive circuitry.


Multiplexed gas discharge displays could be a little finicky to drive, to

keep down anomylous ghosting and partial ignition.


In the absence of a datasheet, your first task would be to distinguish the

digit anodes from the segment cathodes.

You might be able to do it visually by looking at the internal


Otherwise experimentation with two probes connected to a 150-200V power

supply with a series limiting resistor of 200K or maybe even higher to

start with.




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