special readout display Technology from 1969 projection and moving coil - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 22, 2023, 09:11:11 am
content: I had the idea i have seen and touched it all :-)how wrong was Ijust found this frequency counter at a local fleamarked,it looked like side lit displays, those are also cool vintage and all that,but it turned out to be even more nice and special,here is a little video if you like to see all the detailshttps://youtu.be/6h7kBTZuICg

author: Gyro
author_rank: Super Contributor
timestamp: July 22, 2023, 10:12:30 am
content: Beautiful technology. Member Mike'sElectricStuff did a writeup on the 3336 which used the same technology...https://www.electricstuff.co.uk/venner.htmlVenner invented the mechanical timeswitch that went on to be used in all UK street lights until the advent of daylight sensors.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 22, 2023, 11:10:23 am
content: thanks a lot Chris, i have added that link to the video descriptionat the bottom of that page he show exactly my model,but I think that picture could have been from the net ?since mike also make youtube videos and i was not able to find anything

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 22, 2023, 11:51:19 am
content: I once demolished a few similar displays.They had 12 light bulbs (numbers, dot and some extra, maybe a plus sign or slash) in a 3 by 4 array and each light bulb had it's own lens.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 22, 2023, 09:33:18 pm
content: so what you talk about is a side lit ?

author: TimFox
author_rank: Super Contributor
timestamp: July 22, 2023, 10:09:52 pm
content: Some of those I remember from ca. 1970 had individual "slides" with numbers or symbols between an incandescent bulb (one per slide) and its focusing lens to image the slide on a ground glass.This could be very flexible, with any reasonable number of slides and arbitrary symbols as required.I don't remember the name of the US manufacturer of these displays.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 22, 2023, 11:53:59 pm
content: what i think you talk about Timis the side lit, or edge lit, as we use to call them,it consist of thin plastic or acrylic slides with engraved numbers, and one individual bulb lit each slide where the number then light upthey are also super cool and vintage, also from 1960-70there was a nice overlap with the nixie area,then the nixies won it all..

author: themadhippy
author_rank: Super Contributor
timestamp: July 23, 2023, 12:59:11 am
content: One of these by any chance? skip to 10:40 for the relevant bit

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: July 23, 2023, 02:12:52 am
content: Quote from: TimFox on July 22, 2023, 10:09:52 pmDid you think of one out of those:https://www.industrialalchemy.org/tubepage.php?item=10&user=0

author: TimFox
author_rank: Super Contributor
timestamp: July 23, 2023, 02:44:56 am
content: Quote from: oz2cpu on July 22, 2023, 11:53:59 pmNo, the ones I mentioned were rather deep modules, with a miniature projector for each displayed symbol.I think they were like the "IEE 10000-1819-B Projection Display" discussed in Neomys Sapiens' post above.The "slide" for each symbol was maybe 5 mm diameter, for a 25 mm ground glass.I have also seen the edge lit ones you mentioned: they were not so deep from the front panel.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 23, 2023, 08:58:44 am
content: exactly tim, now i know what you think about,the video themadhippy posted at 1040 show exactly what you talk about,this basis idea behind that design i like, since there are no moving parts,how ever the adjustments of all projected pictures, so they align correctly to the screenmust be a nightmare, the video also clearly show how bad they can be to hit the correct spot :-)I dont think i got any of this model stocked, but i do remember taking some apart as a kid 40 some years ago

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 23, 2023, 12:14:18 pm
content: Indeed. Not side lit, but the same internals as themadhippy links to in his posted video.Even though the light bulbs are obviously not all in the center, you can project all digits in the center by using lens shift in photography, or mechanical keystone correction in a beamer.

author: TimFox
author_rank: Super Contributor
timestamp: July 23, 2023, 01:01:44 pm
content: The advantage of the back projection onto a ground glass is that the large symbols are all in the same plane.I found it amusing to watch nixies count, since the cathodes were arranged to minimize obstruction of each other, and the incrementing numbers went back and forth like a trombonist.