Odd 7-segment display

Feb 14, 2007 31 Replies

Came across a 90's vintage IR controller for printing industry (drives Q-H lamps for drying ink in the paper path) that uses a single-digit 7-segment display that looks like a nixie tube (more like a white-hot wire segment) display. The 16-pin DIP socket is marked IEE-Atlas, and the single-digit display is marked "IEEFFD21 5DX C". Each digit display is 15 pin on a 16 DIP pattern.



I've done the requisite Google, but come up with nothing. The drivers on the PCB are MC14511BPC which is a standard CC LED 7-segment driver.



What are these? They don't look anything like LED segments (I can see each wire-like segment behind the glass front of each digit's display). Can I just replace these with a common LED display? Or are replacements available?



Thanks,


John English

Incandescent wires? RCA called them Numitrons.

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Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida

Search for: IEE FFD21

Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida

Once upon a time there were incandescent 7-seg annunciator devices, under various names. Minitron and RCA's Numitron are two names, but do a google search on "incandescent" and "7-segment" for heaps of background.

Thanks.

No replacements available.

So, since this uses the MC14511 driver, which was designed for LED 7-segment displays, all I have to do is provide resistors to each element and rewire for a common-cathode LED display, right?

Thanks,

John English

When I was young and enthusiastic, I built a frequency counter that used these. I think it was a Practical Wireless design. It's still around somewhere ...

Arfa

Sounds like a Numitron incandescent filament display. These are getting very hard to come by.

James Sweet sez:

Purchasing LED 7-segment replacements and associated kit (resistors, etc.) tomorrow to convert to a 21st century technology.

John English

A little clarification, please...

I'm all ready to start looking for a CC display, when I look at the data sheet for MC14511BCP and it has example circuit hookups for both CC and CA.

I thought a driver output was for one or the other "gender", either CC or CA.

Am I reading this right? Can I use either without further need of other configuration or circuitry? Seems too good to be true...

Thanks, Dave

John English

The data sheet is here:

Due to bug in the data base, the previous link pointed to MC14512...

Thanks,

John English

A second reading of the ds shows that, indeed, a transistor is needed to use a CA display with the MC14511.

[gotta stop these early morning designs...]
John English

I would do happier with you if you stopped changing thread titles.

Sorry, I didn't know this caused a break in thread. My reader simply inserts the re-titled post in the same thread, just with another title. I should have realized that not all reader apps behave the same.

Sincere apologies. Will avoid temptation in future.

John English

Most readers use the message ID and work correctly.

. . . . . . . .

I appreciate it. It is not so much a problem with broken threads, for me, as much as it is that I remember the thread title of threads I have been reading. When you change the thread title, I have to go back and review earlier messages to remember what subject we are talking about.

They used to be popular in petrol pumps in the UK (they are readable in quite bright sunlight).

Andrew Gabriel [email address is not usable -- followup in the newsgroup]

It is. [too good to be true] The device, by itself, is designed to drive a common cathode display as shown in the upper left hand corner on page 6 of this data sheet: http://www.onsemi.com/pub/Collateral/MC14511B-D.PDF Immediately across the page from it is the common anode configuration, which requires an additional transistor and resistor _per segment_ .

I've been known to do that on occasion, but when I do I always put WAS: - it might not help with threading, (my reader also threads messages based on the thread rather than the title), but at least you'd know what the previous parts were about.

Cheers! Rich

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