HP LED displays


Recently, a friend was showing off some old electronic parts he had accumulated over the years. What caught my eye were some 3-digit 7-segment displays. They are marked HP 5082-7433.

I am curious if these are the same parts used in any of the early HP calculators.

-- Richard


Some classics used 1990-0335, later units 5082-7405. There are five digits in these packs so the three digit version you have would not be compatible.

Edited: 17 May 2009, 6:09 p.m. after one or more responses were posted


They must have mad a ton of different versions of various LED displays. I have the pretty neat "thing" that they made to showcase some of their LED displays of various types. It makes a great centerpiece for my calculator collection, here are some pics:







Edited: 21 May 2009, 11:00 p.m. after one or more responses were posted


Interesting. The power receptacle looks similar to the one on my HP Model 46, which has a fuse and reversible voltage selector card (120/240). Is it?

Also, while on the topic of the HP 46 (and HP 81 as well), I found a cheaper and more available printer ribbon than the Porelon 483-B/R. It is the Nu-kote NK80BRC and cost me $2.99 at Office Depot.

Thanks for the neat photos.



The power receptacle looks similar to the one on my HP Model 46, which has a fuse and reversible voltage selector card (120/240). Is it?

Yes, it looks like this display board uses the same power connector as the 46 and 81 do. My guess is that this display board was built in the late 1970's near or after the end of the 46 and 81 production cycles. It has a non-standard HP serial number, 332-2, I can't tell the date from that.


Awesome pictures, Katie. Thanks.

I am curious what the BNC connector is for. Any ideas?

-- Richard


I'm not sure what the BNC connector is for, it reads as a flat 5 VDC. It might be for some 5 volt add-on device but that would a really strange connector to use. I need to take it apart to see what's going on in there.....


Cable TV? :D


Yeah, it could be used to feed 5v and data to an external device. I'm wondering, could it be used to load data INTO the displays from an external device like a keyboard?



Some HP logic probes had a BNC plug on the end of the cable for the 5V (and ground) connection. And thus some HP instruments have such a socket to plug the logic probe into when you're testing them.

I know my 6940B Multiprogrammer has one inside the front door, and my 59403 Common Carrier interface has one on the back. I am told the I/O module extenders for the HP98x0 and 98x5 series have such connectors too, but I've not obtained those (yet!)



Yes, I think that's it. The BNC connector is hooked directly to the +5V on the power supply board. Here's a picture of the inside of the display:


The date codes on the chips indicate that this was likely made in early 1983, I thought it would have been made earlier, but I guess the smart LED displays that it shows off must have been hot items around that time. It's running a 6802 microprocessor with 8K bytes of EPROM, not exactly state of the art in 1983 but it got the job done.


Edited: 21 May 2009, 11:10 p.m.


There are five digits in these packs so the three digit version you have would not be compatible.

I think my freind may be more than a little relieved that they are not usable in a calculator. He seemed a bit nervous when I borrowed them.

-- Richard


There were small HP LED displays in 3, 4 and 5-digit clusters. The last was the type used in Classic calculators. I still have some of each variant, I bought them as a small surplus lot (may be from Jameco, not 100% sure) by mail around 1977; however some of them have non-working decimal points.

Please feel free to correct mistakes in this message if you think it will be for good.

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