We’ve seen a bunch of replacements for nixie tubes using LEDs and edge-lit acrylic for the numbers. But one of the earliest digital voltmeters used edge-lit Lucite plates for the numbers and a lot of incandescent lamps to light them up.
[stevenjohnson] has a Non-Linear Systems Model 481 digital voltmeter and he’s done a teardown of it so we can get a glimpse of the insides. Again, anyone who’s seen the modern versions of edge-lit numeric displays knows what they are: A series of clear plastic plates with numbers (or characters) etched into them, each with a light source beneath them. You turn one light on to light one plate, another to light another, and so on. The interesting bit here is the use of incandescent bulbs and the use of sequential relays to cycle through the lights. The relays make a lot of racket, especially with the case open.
[stevenjohnson] also notes that he might have made a mistake opening up the part of the machine where the plates are stored as it took him a bit to get the plates back in place and back in the unit. We’d imagine it was pretty loud if you were taking a lot of measurements with this machine, although it looks great inside and, obviously, the idea is a pretty good one. Check out this edge-lit nixie tube display or these edge-lit numeric modules.
15 thoughts on “Before There Were Nixie Tubes, There Were Edge-Lit Displays?”
Oh man, I couldn’t imagine if devices today had that sort of haptic and audible feedback. It’s a pleasure to see how devices worked and sounded in the past.
My funnest sound from the past was when my personal computer drove the IBM Selectric the one with the ball. Just watching the ball move change its head to hit the correct letter was amazing.
Devices still make sound, it’s just display that don’t, except for some non LED monitors that develop an annoying buzz or whine of course.
Wow that sound is very satisfying.
I remember one of the first digital volt meters I used was with a part time job whlie going to tech school in the late 60’s. Don’t remember who made it, but remember how it worked. It had a mechanical counter much like a mechanical speedometer, that was drive by a motor. The motor also turned a multi turn pot to balance a bridge. It was always fun to watch wheels spin and listen as the motor spun up real fast to get close to the final value. As it got closer you would see the counter slowing down to the final value, then you would see the last digit slowly turning with any slight change. It wasn’t as loud as the stepping relays in the edge-lit unit, But,it was auto ranging, and you could hear the relays click as it selected the correct range and then the motor started to spin.
I want one, and now. :)
That sounds incredibly cool! Almost drooling here…
Shounds good, I would quite like one too. Next time I have parts, money, time, I’ll make one… oh, maybe next year.
Staying thst I have a couple of those old mechanical phone switches somewhere.
I wonder if I can 3D print them.
You can 3D print long term reliable contacts? Very nice!
Well it would sound right.
Would this happen to be it? http://www.myvintagetv.com/voltmeter/front.jpg
Thanks for this. I actually used one of these when I worked at North American Aviation in the mid 60’s. It was the first digital voltmeter I ever had experience with.
I had one of the NLS meters, think it was a model two. Had those stepper relays in it. Had a bad HV cap in it when I got it. (For the tubes.) Remember when I subbed in another HV cap and fired it up… Those steppers took off and rather startled me. Still own a Cimron 6200 DVM (DC only, without AC or Ohms plugins, which I also have.) Anyway it has same stepper null “system” only it uses reed relays on the input ladder. Not near as noisy as the rotary steppers. But still startling to those unused to hearing noises come from a DVM. Why do I hang onto it? Still the only meter I own that will read a tenth of a microvolt!
This would be good as a part of an electro mechanical music machine
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