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Topic: LED clock display (Read 679 times) previous topic - next topic

Graynomad

May 06, 2011, 09:11 am Last Edit: May 06, 2011, 09:13 am by Graynomad Reason: 1
I'm thinking of using this LED clock display (data sheet attached) to display either numeric data or the time.

But from what I can see the DP2 and colon LEDs are wired in parallel. This would mean that they can't be individually controlled which in turn makes the display totally useless for either.

Have I missed something?

______
Rob


Rob Gray aka the GRAYnomad www.robgray.com

Coding Badly

That's what it looks like to me.

Does the number of physical connections match the number in the schematic?

Graynomad

I haven't got one but the photos show 12 pins so I'd say yes.

I've emailed the distributor (no answer yet), but as it stands this is totally useless, how could they make such a thing and have it on the market?

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

James C4S

Quote
how could they make such a thing and have it on the market


Couple of reasons.  1) Manufacturer intended this to be sampled with the final product customized.  2) this is a low cost way to make the display adaptable to a variety of applications. 

In the case of #2, you would physically black out the colons or decimals points not needed in your application.
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johnwasser

I agree that the schematic is for a circuit board that can EITHER be used as a clock display or a numeric display.

Perhaps you can cut some traces and add a lead to give you independent control of your colon.
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Graynomad

That's probably why they are so cheap :)

I can't play with cutting tracks because this could be a product, and also I need to be able to alternate between time and numbers under program control.

So this display is useless. I thought I'd found a better one at Mouser but just realized it's common anode :(

I can't believe these are so hard to find.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

johnwasser

Did some searching on DigiKey.com and it looks like the Lite-On LTC-4727JR (Red) or JS (Yellow) has the capabilities you want for $3.96 each.
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Graynomad

#7
May 07, 2011, 05:03 am Last Edit: May 07, 2011, 06:28 am by Graynomad Reason: 1
Thanks John,

I had seen those models but after a mind-numbing hour or so looking at spec sheets I missed the fact that the three extra DPs had separate pins. I can use them and blank out the "degrees" LED.

I'll revisit them, they are smaller than i'd like though.

There are a stack of displays on the Mouser site and some that look good, but when you try to find the part on the manufacturer's site they don't exist, for example the MSQCxxxx is listed as an Everlight product, search for that on the Everlight site and you get nothing. Not very confidence boosting. The product is actually from Fairchild but I think Everlight has bought the rights to the LEDs from them, maybe they just haven't updated their web site or maybe they intend to retire many of the products.

Now realistically I will probably never use more than about 10 displays so I could just buy them now, but it goes against the grain to use an orphaned or hard to find product with no second source.

Who would have thought such a simple thing would be so hard?

Maybe the best thing to do is use discrete digits and a few LEDs.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

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