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somehow this project is doomed .. or I do not carefully enogh check footprints

A project log for 384:LED

Mini (1.44'' x 0.94'' or 24mm x 37mm) 8X16 RGB LED Array. 128 RGB LEDs with three LED chip each gives 384.

AlexAlex 04/06/2016 at 19:387 Comments

I last logs I wrote about two errors and how I thought I would could fix them. But now the errors did strike back. I think it was mostly may fault.

First the p-fets. Well TSOP6 is the same as SOP23-6. Could have noticed that. I would need TSSop6 to use the original boards. But in TSSOP6 you do not get the footprint I needed. So the controller board is not fixed.


Second the LEDs. There are two different pinmaping schemes for it. I I did order the wrong. Well that is what happend if you sort them by price on aliexpress. Here are two pictures from aliexpress:

Different position of the common Anode Pin!

ill now try to get the right LEDs. And in parallel redesigning the controller board. If the new LEDs do work I will order only a new controller board. If not I will maybe order both new (or abort this project out of frustration).

Discussions

AVR (lordKiCAD) wrote 04/07/2016 at 01:05 point

I tend to make custom footprints for every component I use, takes a little bit longer in the schematic phase but its well worth it, and saves on fail boards. We've all messed up footprints though its just part of the PCB game :) 

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esot.eric wrote 04/07/2016 at 03:47 point

Thanks for the reminder... I once found it quite handy to print (on paper) the design to match footprints with components. I might be doing that again soon! Though that doesn't help with pinout differences.

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Alex wrote 04/07/2016 at 08:44 point

Yes, making a paper test print of the PCB is handy if you have already all components by hand. Sadly I do not always have them when ordering the PCB.
This would have helped with the mosfet error. But as you said not with the LEDs.

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AVR (lordKiCAD) wrote 04/07/2016 at 14:43 point

I definitely have done that a few times myself, especially with components who's mechanical drawing has the dimensions labeled in weird ways

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Yann Guidon / YGDES wrote 04/06/2016 at 19:53 point

With PLCC6 RGB LEDs, I've found 3 DIFFERENT PINOUTS !

aliexpress is insane, I'm not using it anymore...

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Alex wrote 04/06/2016 at 20:23 point

The only reason for using it ( and other chinese sources) is the price.
If the second order of LEDs is right, I am still cheaper than ordering
only one time at farnell/elemnt14. When doing this stuff as hobby I can
normally wait for the shipping. And do other project while waiting on the mail. 


But I would never use it on a professional or time sensitive project.

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Yann Guidon / YGDES wrote 04/07/2016 at 00:11 point

I know it all well...

Good luck !

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