Building a 7 segment LED display - Please help

Thread Starter

Big KJ

Joined May 25, 2008
21
Sgt Wookie,

I'm really happy! :)
Many thanks for your great help.

Tomorrow I'll have the PCBs to be made!
Hope they can give the PCBs by the end of the week.

Again many, many thanks for the help! I'll let you know the results and, of course a photo of the assembly!

Obrigado!!



Cumesoftware,

I guess you are in Lisbon too, as myself!
Anyhow, just in case, I'll reply in english:

Many thanks for the tips.
Now I do have all the parts but I looked last week at Minitron and even at Dimofel (God you pay for the plastic bags and stapples more than for the components...) and they do not have none...

Anyhow I found the 5521 at a fantastic price at Total Electrónica (Praça João do Rio 2nd corner to Almirante Reis).

They have lots of hard to find components at great prices.
And if Mr. Brogueira is there, for sure you'll get a great help too.
They also etch PCBs for a nice price.

If you don't know them, just check, it might worth to step by.

Anyhow, thanks for the indications!

Cheers from Lisbon!

Obrigado!!
 

SgtWookie

Joined Jul 17, 2007
22,221
Just to be clear:
1) The EPS file still has the 12-position selector switch in it. This portion should be discarded.

2) You will need six complete copies of the EPS files made, because you will need six main board assemblies. You will only need three of the LED boards, but spares aren't a bad thing to have.

3) When you are assembling the 7-segment dual LED boards, you must first solder on the two 10-pin dual header strips, inserted from the bottom side of the board. If you try to attach the LED's first, you will have an impossible time attempting to solder the dual header strips later.

4) The header strips were used with the idea that you would use ribbon cable jumpers to interconnect the driver board to the LED board. Since the dual header strips on the 7-segment LED boards are installed in the bottom of the board, you should also insert the driver board dual header strips in the bottom to preserve the order of the connections. Otherwise, you will drive yourself bonkers trying to figure out how to configure a ribbon cable to connect them up properly.

5) You do not HAVE to use header strips and ribbon cable connectors. However, this will greatly simplify your wiring chores.
 
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zorbzz

Joined Jun 16, 2008
20
Far Out!!!
What a TOP Bloke you are SgtWookie taking the time to help this guy out.
Lets just hope he comes through and shows us the final pics.
 

zorbzz

Joined Jun 16, 2008
20
Typical.
Its no wonder people dont help people anymore.
I was really interested in seeing the final result.
 
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Thread Starter

Big KJ

Joined May 25, 2008
21
SgtWookie,

I got recovered from my second spine surgery finnally.
I know that it was a long ago but as I did PM you, I could not sit down and work for a while...

Well, the point is that: IT WORKS!!!!

I just finished it, and put it on a rack case.
It will take a few more days to complete the assembly, but by that time I'll post a few more images.
Now I have to do a front bezel for it, maybe in plexiglass.

There was two things I needed to change from your schematics:

1. D8 got to be removed to avoid the decimal point to be on (once removed it works perfectly)

2. R6 and R7 need to be changed from 180 to 820 ohms so the MSB have the same intensity.

I enclose a pdf with a few images of what I did.

This circuit is now making part of a 23 audio/video switch for 3 diferent displays. It also provides feed for the 24 tally lights on the displays.

I almost got nuts with all the wiring, but once it done it worthed all the trouble.

Many thanks for your unbelievable and kind help on this SgtWookie: you're the best.

Again sorry for this delay, but I couldn't have it done before.

Cheers from Portugal
 

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SgtWookie

Joined Jul 17, 2007
22,221
SgtWookie,

I got recovered from my second spine surgery finally.
I know that it was a long ago but as I did PM you, I could not sit down and work for a while...
I'm sorry that you had so many troubles with your back. I have some dear friends that have gone through that agony. I'm very glad that you are feeling better. Please take it easy for awhile, and follow your physical therapist's instructions. Strong back muscles coupled with proper lifting/bending/twisting techniques are the best way to prevent future injuries.

Well, the point is that: IT WORKS!!!!
That is indeed good news! Had it not worked, I would've wondered where you'd gone wrong.... ;)

I just finished it, and put it on a rack case.
It will take a few more days to complete the assembly, but by that time I'll post a few more images.
Now I have to do a front bezel for it, maybe in plexiglass.
Plexiglas is good, but will scratch easily. If you DO use Plexiglas, use a soft clean cloth (cloth diapers are ideal) and Lemon Pledge to clean it. Do not use paper towels; they will scratch.

There was two things I needed to change from your schematics:

1. D8 (had) to be removed to avoid the decimal point to be on (once removed it works perfectly)

2. R6 and R7 need to be changed from 180 to 820 ohms so the MSB have the same intensity.
As far as D8, I must've missed something somewhere. I can't tell you offhand, since I can't view the file while I'm replying.

As far as R6 and R7 needing to be changed, that's somewhat of a mystery at the moment as well. I went strictly by the specifications in the datasheet, or so I thought.

I enclose a pdf with a few images of what I did.
Thanks - nice job on that! :)

This circuit is now making part of a 23 audio/video switch for 3 different displays. It also provides feed for the 24 tally lights on the displays.

I almost got nuts with all the wiring, but once it done it worth all the trouble.
Wiring up such a project can be quite a chore. Imagine how nasty it would've been if you didn't have ribbon cable! :eek:

Many thanks for your unbelievable and kind help on this SgtWookie: you're the best.

Again sorry for this delay, but I couldn't have it done before.

Cheers from Portugal
Thanks for your report, and I'm glad that everything worked out, despite all the difficulties and downtime you've faced! :D

Stay in touch, and do the most important thing - take care of yourself!
SgtWookie
 
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