Edge-lit DVM Display

[Mac Doktor]

Another day, another bargain:

https://www.ebay.com/itm/375631941251

Terry Bowman, KA4HJH
"The Mac Doctor"

https://www.astarcloseup.com

"If only you could see what I've seen with your eyes."—Roy Batty, Blade Runner

[ZY]

On one hand I want it, but on the other hand I can't bring myself to take apart the vintage system just for the display.

And on the third hand... the price

[gregebert]

Not worth the hassle unless you are a wealthy collector who wants to look at it admiringly.

My very first digital clock was built from a 5-digit edge-lit DVM around 1980, and like this one, it had stepper relays. Making the clock work like a clock was easy. It was pretty amusing when midnite arrived and it went kachunk-kachunk-kachunk for several seconds. But I quickly found out the relays were unreliable despite numerous attempts to clean them, and the clock would lose time and various digits would randomly not light. Not all of the problems were with the relays; the lights were not solidly connected, either.

I kept it around for several years, and when I relocated for my job in 2005 I left it at my old desk at Intel and have no idea what happened to it. Hopefully someone gave it some love despite the unlikelihood of getting anything in return, but I suspect it's buried in a landfill somewhere.

[Mac Doktor]

On Sep 5, 2024, at 5:55 PM, gregebert <greg...@hotmail.com> wrote:

But I quickly found out the relays were unreliable despite numerous attempts to clean them, and the clock would lose time and various digits would randomly not light. Not all of the problems were with the relays; the lights were not solidly connected, either.

Do you mean the steppers? In pinball machines the contacts are supposed to be cleaned with a special tool that didn't take the gold plating off. No Deoxit in those days.

Terry Bowman, KA4HJH
"The Mac Doctor"

https://www.astarcloseup.com

"I’ve seen things you people wouldn’t believe. Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near Tannhäuser Gate. 

"All those moments will be lost in time like tears in the rain."— Roy Batty, Blade Runner

[gregebert]

Yep, those pesky steppers. They stepped-along just fine, but the contacts were worn-down to copper, which oxidized. Also, they lost their "pinch" and to fix that would have required complete disassembly and carefully rebending, if that's even possible. These weren't anything like the stuff Western Electric used in their telephone switches.

The only thing I really miss from that DVM is the indescribable aroma of the conformal coating.

[rwhi...@gmail.com]

I have one of these working in my collection - they are super-neat to watch and hear operating.     Here is a short video:    https://youtu.be/JdY0dHvjo-A

I paid a fraction of the asking price though.   

-Rich

[Mac Doktor]

On Sep 6, 2024, at 10:50 AM, rwhi...@gmail.com <rwhi...@gmail.com> wrote:

I have one of these working in my collection - they are super-neat to watch and hear operating.     Here is a short video:    https://youtu.be/JdY0dHvjo-A

Awesome.

I paid a fraction of the asking price though.   

Someone just bought it, best offer.

Terry Bowman, KA4HJH
"The Mac Doctor"

https://www.astarcloseup.com

[Rob B]

I owned one of those when I was a kid [bought it out of state surplus].  Ever since, I've always wanted to get another one.  Alas, I am but a poor collector who wants to look at it admiringly....