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### Topic: What hardware can drive one long row of 100 LEDs (Read 3751 times)previous topic - next topic

#### David82

#30
##### Apr 24, 2012, 05:19 amLast Edit: Apr 24, 2012, 05:21 am by David82 Reason: 1
You're right. The spacing would be a little tricky to work out. The spacing won't be even due the the fact that the center of the black keys are right between the white keys. Printing examples on paper is a great technique though. Instead of trying to do the math, I would just keep increasing/decreasing the spacing until it fit. The goal is to have each LED centered on each key. I would do it in octaves though. From c to b. You don't need to use the 3mm LEDs. You can use the really tinny ones if that is cheaper.

#31
##### Apr 24, 2012, 05:32 amLast Edit: Apr 24, 2012, 05:39 am by CrossRoads Reason: 1
The spacing is not difficult, just some math, resulting in this.
I just printed, will cut & try again.
I have wife's piano, and also an Fatar SL-990 electronic keyboard to try the spacing on.

Rats - still a little off, on the high side this time.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### David82

#32
##### Apr 24, 2012, 07:05 am
I see you're starting on G# for some reason. In my particular case, the piano starts off with A and the highest note is C. Since it is clear that not all pianos start off with the same note, it may be best to just stick to the conventional c through b and just make one more octave than the paino would typically have. That would be used to cover any variation in starting and ending keys.

EDIT: doing a little more research, the lowest note on an 88-key piano seems to always be A0 while the highest note seems to always be C8.

#33
##### Apr 24, 2012, 07:36 am
I had it starting on G# and leaving it off the left most board, made sense when I started; spacing wise I think I have a better handle on it now.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### David82

#34
##### Apr 24, 2012, 03:19 pm
Ok. I guess next step would be to get a prototype printed, populate it, see if everything works on a basic electronic level and then see if it can be interfaced with via PC.

#### David82

#35
##### Apr 25, 2012, 03:26 am
I'm ready when you are with anything you need to get this moving along.

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