Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
Cubdriver:
--- Quote from: Vince on June 27, 2022, 08:27:59 am ---As much as I enjoyed the video, I think you should stop making them... for the good of your TE ! :-DD
You are too nervouis when on camera, at the beginning you dropped the display assembly then tools soon after ! :scared:
The health andf well being of your TE comes first, our curiosity second.... which is satisfied anyway with the still pics.
That display unit looks really cool and cleverly designed indeed ! 8)
Thanks to your pics and video I now realize I was wrong about how I thought this antique display technology worked !
From your previous videos, with all the noise the instrument was making when those digits were changing, I thought the display was a mechanical device and the noise were the digits being being moved in an out, like you have on some old alarm clocks...
But no ! So the noise is entirely due to the switches behind the display, but the display itself is 100% static, no moving parts. The 10 digits are all stacked up, immobile, made of an engraved piece of glass or perspex, that's lit from the bottom/edge via all these lamps ! How cool... so the display itself can't wear out and can be operated at high speed, no worries.
So it's very much the same concept as Nixie tubes, all digits stacked in front of one another, common terminal and light the digits you are interested in. Only difference is the source of the light. Incandescent in this meter, and gas discharge in the Nixie.
So this old display is actually more repairable than a Nixie... all that can go wrong is a bulb frying from being turned on and off all the time at high speed, but they are designed to be very easily replaced so no worries, they anticipated that. Whereas the Nixie once it wears out or loses gas or whatever... not much you can do !
Yeah I like your instrument more and more, really cool display, they came up wit a really nice design for something this old ! :-+
May you keep ti running for many years to come. 8)
The one thing I don't quite understand though, is that it looks like there are only 8 bulbs per digit, so not sure how they light up the two remaining ones ?! :-//
--- End quote ---
The tool drop was just because there's so much crap on the bench that it's near impossible to move anything without something else toppling over. And the display drop is not so much nervousness as it is the fact that I'm a klutz! :-DD
Yes, the displays are kin to the nixie in their arrangement - stacked digits with a different light source. A bit bulkier, too, and lacking the digit stacking optimization that the nixies have for better readability, but certainly ground breaking for their time.
As for the 8 lamps per digit, the confusion is understandable given that the ground springs connect pairs of columns and the pictures I've posted thus far don't show it clearly, but in fact there are up to 12 lamps per digit - look at the photo below, taken at a better angle to show this - the digits are wide and thin, and each has three columns of four lamps under it:
Truth be told, until you mentioned it and prompted me to look more closely at the other pictures, I hadn't noticed that there were only four lamps in each column and was thinking the same as you were - associating the paired columns based on the grounding springs. Interestingly, the frontmost digit is the 1, and the second in the stack is the decimal point, thus the empty cavity in the front middle of the leftmost digit - it doesn't need the DP.
And on that note, it's waaaaaaaaaay past my bedtime at just shy of ten after five in the morning. :o On a work day. :palm: Time to hit the sack.
-Pat
tggzzz:
--- Quote from: bsdphk on June 27, 2022, 08:20:03 am ---I doubt that cable is for sub-sea use, almost all such cables have at least one layer of steel, and much thicker envelopes.
--- End quote ---
No, they don't. A major design constraint is the need to fit as much as possible cable on a cable-laying ship, and that precludes steel armour.
Subsea cables are protected from trawlers and anchors in shallow waters. That involves them being buried and usually armour plated. Where trawlers/anchors are not likely to be an issue, they are not armoured.
The TAT-7 cable was steel core, copper coating, dielectric, copper sheath, thin protective plastic coating (about the same as the red layer, from memory), and nothing else. 2400nm was unarmoured, 300nm armoured. The 61.8ohms impedance was defined by the diameter of the steel core necessary to support the cable's weight, the dielectric constant, and the maximum diameter necessary to fit on the cable ship. That fixed all the parameters, and 61.8ohms is what emerged. It was a similar diameter to the cable shown.
Another point is that the cable is extremely inflexible, and would be very difficult to draw between exchanges. On land they would have used single coax cables, and added more as and when extra capacity was required. Another point is that point-to-point microwave links were preferable to coax: faster/easier to install, higher capacity.
--- Quote ---But it is not a trivial cable either: It could transfer between two and thirty thousand simultaneous telephone conversations, depending on the route and repeater spacing.
--- End quote ---
That would depend on the age of the cable; there is no indication of that.
med6753:
--- Quote from: Cubdriver on June 27, 2022, 07:57:09 am ---And a quick video showing that more of the lamps in the display are now working:
(I need to get a camera that can close focus!!)
-Pat
--- End quote ---
That is so cool. :-+ :-+
TERRA Operative:
Bah, I just won a TDS220, with some parallel port only version of a comms module.
Paid equal to US$62, with some probe and a Japanese manual.
Lets see if it actually works when it arrives. |O :-DD
med6753:
--- Quote from: TERRA Operative on June 27, 2022, 10:57:11 am ---Bah, I just won a TDS220, with some parallel port only version of a comms module.
Paid equal to US$62, with some probe and a Japanese manual.
Lets see if it actually works when it arrives. |O :-DD
--- End quote ---
If it doesn't you'll have your Japanese wife to answer to. :P :P :-DD :-DD
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