I was looking through my parts collection and found a handful of HP displays, part# 1990-0335. I cannot find data on these displays but on the back is an "H" which I assume is the intensity value.
I picked these up when I worked at HP and pretty sure these were used in the classic calcs. (I used one to repair a failing HP 67.)
I would like to save a few but others will be up for sale. No idea on the price but no doubt fairly expensive these days. (I've seen them as high as $100/ea!) What's a fair price?
Can anyone suggest a simple test circuit? I can do a quick test (like "8.") but a simple multiplexed arrangement would be better.
I could put them on ebay but would prefer the folks on MoHPC have the 1st shot!
Cheers!
Mark
Multiplexing a display is fairly involved. Just testing the segments with (say) 5V and a 1K resistor should be good enough.
$1ea sounds good, I'd buy the lot :-))
cheers
Tony
(11-22-2023 02:08 AM)teenix Wrote: [ -> ]$1ea sounds good, I'd buy the lot :-))
HA! Pretty funny, Tony. :-)
And yeah, that's how I've been testing them.
Mark
(11-22-2023 02:08 AM)teenix Wrote: [ -> ]$1ea sounds good, I'd buy the lot :-))
Maybe for 1 Ningi, which is a triangular rubber coin 6800 miles on a side.
I did wonder about crowd funding to get them re-manufactured, they would still be popular in electronic hobby circles. The tooling would probably be too prohibitive.
(11-22-2023 03:06 AM)teenix Wrote: [ -> ]I did wonder about crowd funding to get them re-manufactured, they would still be popular in electronic hobby circles. The tooling would probably be too prohibitive.
If it's practical to use 01005 LEDs with light pipe style diffusers to shape the segments, it might not be too crazy expensive.
Or just make a small segmented LED display with a reverse polarizer and a red LED backlight.
Interesting replies. Not exactly what I was expecting. Looking at ebay I guess.
(11-22-2023 06:19 PM)mbielman Wrote: [ -> ]Interesting replies. Not exactly what I was expecting. Looking at ebay I guess.
Sorry! In principle I'm quite interested in getting some, as I have multiple classics with LED failures, but on the other hand, I am presently unable to make a credible offer.
No worries. Just trying to offer these to folks that need them. If I could get $100/ea I would be doing a jig. But cost is negotiable.
I tested them today and they all work (a simple ALL SEGMENTS ON test) but there is variability in intensity. I checked the back and there are varying characters like J, H, etc so I suspect I grabbed a bunch of samples. Just a guess. Cannot find info on this intensity rating...
If you (or someone) needs one, you might want to pull one and check this rating. I might have one.
Yes, the letter on the back is the intensity letter. When changing it is adviced to use one with the same letter. This is easier said. Nowadays you will be very glad if you are able to grab one at all.
Andi