Sperry SP-425-08 Display - Datasheet?

Brent Hilpert bhilpert at shaw.ca
Sat Jan 4 14:56:51 CST 2020

On 2020-Jan-01, at 6:14 PM, Anders Nelson via cctalk wrote:
> I'd love to see examples of driving circuitry if it's not too much trouble. 

Remarkable that Tom found someone with spec sheets for the same type.

Two examples of in-use are here (see the linked PDFs under tech data):
	http://madrona.ca/e/eec/calcs/SanyoICC83.html  (display construction looks similar to the type you have)
	http://madrona.ca/e/eec/calcs/CommodoreUS10.html  (Beckman Panaplex II display)

You'll have to wrap your head around the various voltages and non-standard ground-references, to look instead at the actual potential differences.
In one of them the 'high-side' is the anodes, while in the other the 'high-side' is the cathodes (high-side being whichever is at high potential difference from the logic). In either case, the high-side has to be voltage-isolated from the logic and the switching level shifted across that potential difference. In both cases here, that's accomplished via capacitors. (It was sometimes done with pulse transformers. Today, opto-isolators would be an option).

> On 1/1/20 4:42 PM, Anders Nelson via cctalk wrote:
>> I snagged one of these Nixie-like displays (from a calculator I assume) and


Please don't call them Nixie-like. Yes, they have a gas-discharge glow like Nixies, but Nixies are a very specific thing and very distinct from segmented displays. 10-15 years ago when nixies started becoming retro-cool, ebay listings for vacuum-flourescent displays started started referring to those as nixies.

A little history: Nixies were popular in the 60s for test equipment and the early desktop calculators. 7-segment displays started to take off in the early-70s, and nixies came to be passe/old-fashioned.

For the first few years the segmented market was dominated by 3 types: vacuum-flourescent, gas-discharge, and LED. All 3 of these went through stages from single-digit modules and then multi-digit modules. Lesser players were incandescent (Numitrons, Minitrons) and electro-fluorescent. LCDs came in starting in the mid-70s. GD was eventually wiped out of the market due to the HV requirement and driver expense.


On 2020-Jan-01, at 2:55 PM, Tom Uban via cctalk wrote:
> Not exactly it, but may be helpful: http://www.tube-tester.com/sites/nixie/dat_arch/Sperry_01.pdf

These are the 'other series' of Sperry GD displays I was alluding to.
They are like the Beckman Panaplex II displays in that the anode is a transparent conductive coating sputtered onto the inside surface of the viewing glass, in contrast to the type you have in which the anode appears to be a metal electrode in-plane around the segment cathodes.
They (the 'other series') also bring out all the electrodes individually so they can be used in direct drive or multiplexed.

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