seven segment display history

[Ethan Dicks]

On Sat, Mar 01, 2008 at 08:54:10PM -0800, Brent Hilpert wrote:
> Ethan Dicks wrote:
> > > > There is a vendor and part number etched on the face: Sperry SP-738.
> 
> Forgot before, Heathkit used those Sperry/Beckman displays in their 70's-era
> digital doodads like clocks, indoor-outdoor thermometers, weather monitors,
> tachs, & c., might be a place to look for schematics for examples of real-world use.

Oh, yeah.  I even have one of those 6-digit Heathkit clocks.  Still, the
trick with those is that some of the Sperry/Beckman displays have keep-
alive-anodes, and some do not.  From the one link that was recently
posted, it's clear that there was a large variety of displays made back
in the day, and you could select a display for your requirements (especially
how many primary anodes for multiplexing).

In this case, I have a particular display, one of the more complex ones,
looking for an application; not the other way around.

Still... I'll have to go digging for some Heathkit schematics anyway.
ISTR that my clock is a little funky - either the displays are wearing
out, or I have something going off in the driver circuit.  I _think_ the
symptom was that as the clock warmed up, segments that shouldn't be lit
started to fade in, then the clock went to 88:88:88.

-ethan

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