Looking for info on three multi-digit LED assemblies

[Ethan Dicks]

On 9/2/09, Shoppa, Tim <tshoppa at wmata.com> wrote:
>> So do any of these LED assemblies ring a bell with anyone in terms of
>> type or brand of equipment?
>
> Time code displays? Google terms: IRIG, Symmetricom, Truetime

Good call, but my digging with Google Images isn't turning up any
visual matches.  I'll see if I can't get some reasonable quality
photos of the boards in case the style triggers any recognition.

> Getting sales attention from Truetime/Symmetricom has been very hard the
> past couple of years.

Indeed.  We've had some Symmetricom products at the Pole.
Fortunately, I only have to deal with them if they break, which is not
often.

> If the digits weren't grouped for time codes, then pinball machine score
> readouts

Probably not pinball.  The older one (7447-based) has all 6 digits
jammed together for either a counter or hrs/min/sec with no colons.
The newer ones are definitely 3 digits, gap, 2, smaller gap, 2, small
gap, 2, even though one of them has 4 leading digits, only 3 are
driven by the swath of MC14543s, so I'm going to go with DOY,
hrs/min/sec for both of the newer units, which does suggest precision
timekeeping devices.  Unfortunately, the recent trend has been to LCD
displays, so LEDs are somewhat older and hard to find info on.

> MC14543/CD4543 is actually a very nice BCD to seven segment decoder if not
> the very beefiest output current

I was looking over the datasheet last night - the decode matrix is a
lot like the 7447, except there's the possibility for injecting a
square wave to directly drive LCDs.  That's an odd feature.

Thanks for the nudge towards that sort of gear.

-ethan