----- Original Message -----
From: "Ethan Dicks" <ethan.dicks at usap.gov>
I was recently watching "Goldfinger" and oggling the countdown timer
on the bomb. I don't think I've ever seen that type of display
technology up close, but in principle, it shouldn't be hard to
replicate.
<http://www.vintagecalculators.com/html/calculator_displays.html#Incandescent>
I was thinking that some sort of modern CNC would make short work of
the digit faces - just CAD up some outlines and bang out a few sheets.
Alternately, a pantographic sign engraver might do the trick, with
suitable templates whipped up either by hand on on a CNC.
The compact design for the type marked "KGM M4" looks intriguing as
well - a few slits cut in an aluminum back, and a simple PCB layout
for the bulbs (though I must confess I was contemplating white LEDs
rather than bulbs for a variety of reasons, including longer life
and simpler drive circuits).
As for driving it, I was thinking about something like a '145 O.C.
decimal decoder (as found in Commodore PET keyboard circuits and KIM-1
memory decoder and LED decoder circuits) per display. They aren't
particulalty expensive, and all you'd have to do is pipe in 4 bits and
let the '145 do all the work.
Nixies and other contemporary (and now faded) display technologies
are cool, but any of the glass-envelope types aren't exactly feasible
to reproduce in a home workshop.
-ethan
These displays were used in a lot of equipment. I have an "Advance"
timer/counter with small versions, and a digital clock (ex-fighter control
centre) which has 8" versions.
The digits are drilled right through the Perspex, and the larger displays
have four bulbs per digit, with flat sheets of Perspex.
Jim.