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Pinout for C8021-11 led display?

I found a box (BIG box) of 7 segment 2 decimal point 13 pin LED displays that I want to use for a project. (Jameco product number 176559 - number on the display is C8021-11). Unfortunately, Jameco has no datasheet on this product that I can find. The catalog says that it is common cathode, max 2 volt, 20ma.

The pins are like so looking from the back.

0 0 0 0 0 0 0 0 0 0 0 0 0 No problem. With a 1.80 volt supply, I should be able to map out what is what. Well, yes problem. No combination of any two pins will cause a segment to light, so this particular segment type must have an enable or blanking pin maybe?

So far, no amount of googling has turned up this particular segment's pinout, although with a 24k dialup line I can't say that I have exhausted the search possibilities out there. There are spec sheets on the device, but no pinouts. I have found 10 pin, 14 pin and 18 pin displays, but no

13 pin devices.

Anybody got a pinout for this kind of display module? Or a link to one?

Thanks John

Reply to
John Hastings
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Just a thought- what are you using to test them with? You *imply*

1.8v.

The forward voltage of such devices is poorly defined: it's better to stick a current *through* than a voltage *across*. What happens if you apply 5v through a series 470R resistor? You will neither over-volt them (in either direction) nor over-current them.

Apologies if I've made a wrong assumption about how you're testing them, or if I'm reciting the obvious.

-- Per ardua ad nauseam

Reply to
tersono

You are right. I just meant that I should be able to meter out the diodes with an appropriate input. In fact, 5v with a 480 resistor is what I used. When that didn't work, I just used the raw output from a variable power supply and increased the voltage in steps till I started getting current flow through something.

However... I have discovered that the catalog and the online data sheets are either wrong, or this is a batch that doesn't follow specs. Instead of a 20 ma maximum forward current as indicated, these require at least 55 ma just to begin to light one segment and 75 to get a decent brightness and will go clear up to 150 (!!) without blowing. So, as it turns out, a panel full of these particular displays would really suck power.

Which may explain why I found such a large bag of surplus devices:)

Thanks John

Reply to
John Hastings

Take a peek at

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Your'se should be green, common cathode. (says
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seems to suggest, this is the same device.

--
Kind regards,
Gerard Bok
Reply to
Gerard Bok

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