[Noisebridge-discuss] Help/Advice for a circuit board design.

Daniel Pitts Daniel at coloraura.com
Thu Jan 23 21:27:03 UTC 2014

Hey Hilaire,
Thanks for the reply.

The TD62783 is a Darlington array, I added it to this design so it 
should be fine now.  All the current for the LEDs will be handled fine 
(and within specs) of the TD62783 and the 3 TLC5916 chips.  I was 
actually more interested in comments on the routing of the board, and 
best way to source parts.

Is your place in West Oakland BART accessible? I live in Concord, but 
usually take BART to work in SF.


On 1/23/14 11:42 AM, Hilaire Nollette wrote:
> Daniel,
> Looks like you are trying to drive the whole matrix with one chip, in 
> this arrangement you'll need Darlington arrays, that chip won't drive 
> a matrix directly, I am willing to either face2face at Noisebridge, or 
> you can come to me in West Oakland, I have an electronics lab here. 
> the way you have it setup you are driving too many led's from one pin, 
> 120MA maximum per chip. What you'll need is something like a 2N3096 on 
> each leg of the chip driving the array. I can show you samples of all 
> of this, as well as proper current limiting.
> Let me know,
> Hilaire
> On Thu, Jan 23, 2014 at 11:05 AM, Daniel Pitts <Daniel at coloraura.com 
> <mailto:Daniel at coloraura.com>> wrote:
>     I have a design for a project, and I was hoping to get some
>     face-to-face feedback on the design.  I was thinking Noisebridge
>     might be a good place to do that.
>     It seems that Circuit Hacking Monday's would be a good time to do
>     that, but I would like to see if someone with experience/expertise
>     would be willing to meet up with me at that time specifically to
>     look over it.
>     Board (PDF):
>     http://virtualinfinity.net/electronics/LED%20Display%202%20-%20board.pdf
>     Schematic (PDF):
>     http://virtualinfinity.net/electronics/LED%20Display%202%20-%20schematic.pdf
>     Board (EAGLE):
>     http://virtualinfinity.net/electronics/LED%20Display%202.brd
>     Schematic (EAGLE):
>     http://virtualinfinity.net/electronics/LED%20Display%202.sch
>     The goal of the project is to build a programmable 8x8, 12bit
>     color LED display, and to do it "cheaply", while still maintaining
>     some level of quality. I had a prototype working, though it didn't
>     support the full amount of current required. It worked when
>     powered from a battery, but burned out a chip when I used a real
>     power supply (the 74HCT238).  I added a high-side driver to fix
>     that issue.
>     Anyway, if someone would be interested in talking with me about
>     this, then I'll try to show up on a Monday night.
>     Thanks,
>     Daniel.
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