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1  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: December 02, 2010, 03:58:02 am
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Do you have the LEDs already?
Yes, the 5mm's I got from ebay that will be used in the color bars, and all the single leds which are 3.0-3.2 v drop @ 20,000 mcd and 24ma max. I just order the rectangular leds and they are 2 v drop @ 20ma max which will be used in the 3 led series.

Ok, so I think I got this figured out.
Im gonna use 9 volts 6 aa's and split that up into 2 parts, 4.5 volts and 9.
I will use the 4.5 to run the UNO and the single leds.
I will use the 9 volt to run the 2 leds (6-6.4v) probably at 20ma and also the 3 rectangular leds (6v) at 20ma.

That will give me:
40 ma per color bar x 16 = 640 ma
20 ma per single led x 38 = 760 ma
20 ma per 3 led series x 28 = 560 ma
15 ma per 2 led series on the sides of them helmet x 2 = 30 ma

Which will give me a total of 1990 ma if all the leds are on at the same time, which will rarely happen and if it does it would only be for a few seconds, I can alter the programming to control the ma output at a given time which would probably be down to 1000 ma average,  if that.

Wow, doing this way will save so much current draw, battery life shouldn't be too much of an issue anymore! As soon as I get some spare time I will be throwing this stuff onto a bread board and test the brightness. I might even be able to run less ma in the single leds cause they are so bright, I'd like to try to even out the brightnesses of all the leds as much as possible.
2  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: December 01, 2010, 11:01:10 pm
There will be 38 total single leds in the circuit. So I could use the same battery pack of 6 AA's and make a pos and neg wire coming from the pack from 4 batteries making 6 volts? That would be awesome, anything to save battery life as I foresee that being a pretty big issue.

Here is a video that shows the actual helmet in action (not a replica that was previously posted)
[media]http://www.youtube.com/watch?v=NyBHb3gfr2Q[/media]
You can skip ahead to these times to see its led capabilities:
1:38
2:20
2:42
3:25 (best view of the rectangular leds)

Im obviously not doing the huge led array in the front of the helmet, that would require a huge backpack like they have in the video, I cant even imagine the coding for that either.

Thanks again for all your help with this.
3  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: December 01, 2010, 09:53:09 pm
Hmm...would I be able to use the 5v output from the UNO instead of connecting it straight to the 9v battery pack for the single leds?

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a little oddly layed out
Ya, I tried to lay it out as the components will be attached to the boards, plus it was my first attempt at a schematic  smiley-razz
4  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: December 01, 2010, 08:30:47 pm
Your right about the leds...I totally forgot I got them from ebay a hell of a lot cheaper in a lot of 100. I just pulled up the spec sheet and these ones looked the same but are 3.0-3.2 volt at 24ma 20k mcd.
http://cgi.ebay.com/100-5mm-White-Wide-Angle-LED-20000-mcd-FLAT-TOP-USA-/180348849734?pt=LH_DefaultDomain_0&hash=item29fda10e46

I made a schematic for all the boards except for the shift reg board, kinda hard to see though.  :-[
5  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: December 01, 2010, 04:06:17 pm
Here are the LEDs I'm using:
http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=%2Fspecs%2FW15120_specs.htm

Those are going to make up most the the LEDs in the helmet but I will probably run the rest at 20 or so ma because the ones in the color bars have foam and color gels over them, I want them to run 25-30.

The rectangular LEDs which I am working on a schematic for are 2 volts and 20 ma and I'm going to need 84 of those. I will be wiring them much like the color bars but 3 in a series.

I did a quick rough calculation of 2320 ma of current draw, is that practical for 6 aa batteries?
6  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: December 01, 2010, 03:03:52 pm
Well each led for the color bars has  a 3.3 voltage drop and are capable of 30mA, I drew up a quick schematic of one of the boards, there will be 16 of these total. I will try and post an entire schematic later today.

7  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: December 01, 2010, 11:23:02 am
I am going to try and use 9 volts and parallel up 2 leds in a series, thanks again for all the help/suggestions. I will post a schematic soon.
8  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: November 30, 2010, 10:07:31 pm
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So as such I can't say if it will work or not. In general I would say that you haven't convinced me on the need to use 12V to power the LEDs, to make best use of the batteries I would use about 1V over the forward voltage drop of the LED. Failing that use 4V, any more is wasted power.
If you can draw a section of the circuit I could tell from that.

So you are saying that 4 volts is capable of powering all of those LEDs?
And if I did use 12 volts with the same current draw vs lets say 6 volts would last the same length of time?

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If you have 12V available and you are turning all 4 LEDs on your little card on at once (I assume the 3 pins are power, ground, control) then you are better off wiring them in series - +12V to the 4 LEDs in series to the resistor to the transistor to ground.
I might have to look at this route instead, thanks for the suggestion.
9  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: November 29, 2010, 08:14:25 pm
Thanks everyone for all the input so far, as for other methods vs using shift regs, I already have most of the stuff I need to do it my way, but if that doesnt end up working/fitting in the helmet I will definitely look into alternate routes.

Here are some pictures of this same project that I am attempting except I am trying to make it a little more complex and programmable instead of using LED drivers.

These are the 16 boards for the color bars on both sides of the helmet which will be connected to a single shift reg:


This picture shows the 2 rows of 8 LEDs that go right under the color bars along with the transistor board that controls it. I want to try to make a 16 transistor board so that I can control each individual LED rather than only controlling a vertical pair, this will require 2 more shift registers.


I also want to add rectangular LEDs instead of going the route this guy took by using regular 5mm's and making a pattern from color gels for the light to shine through:


As for fitment, I cant say Im too worried because the helmet is a good deal larger than my head and the arduino and batteries will be in a wallet sized box that will fit in a pocket. This is another guys helmet and what how he fit the boards in:


This is basically what I want it to be able to do, except that mine would have more programmability:
[media]http://www.youtube.com/watch?v=VDtRCbOoTGA[/media]
10  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: November 29, 2010, 05:54:59 pm
I know it is no schematic, just a basic diagram for the layout of the LEDs.

What I mean by both sides is, it will also control the LEDs on the other side of the helmet so that the output of the LEDs on one side is mirrored on the other by using the same shift register, or cant i do that?

As for the matrix your right, I meant to say array. It will act like an equalizer and just light up random LEDs in the sequence.
11  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: November 29, 2010, 05:37:42 pm
I drew out a diagram of how the shift regs will operate:
http://www.flickr.com/photos/55927001@N02/5219302602/

Basically the color bars will have 4 LEDs per board with 8 boards on each side, which is the 64 LEDs I am referring to. Each board will have a transistor controlling the output from the first reg.

Reg 2 and 3 will each have 8 LEDs and control both sides.

Reg 4 and 5 will have 7 transistors controlling the output of the 6 x 7 LED matrix.

Reg 6 will be controlling the EKG with 3 LEDs and the smaller LEDs.
12  Forum 2005-2010 (read only) / Interfacing / Re: Wondering if this is possible/practical? on: November 29, 2010, 03:14:44 pm
Thanks a lot for the reply and the link. I do understand this is a pretty over ambitious first project, I plan to put the whole thing together a shift reg at a time.

As for how I plan to wire them up, I will be using a resistor for each LED and all of them will be in parallel. 64 of them will be wired the same as the link with 4 per board. After that all the other LEDs will be controlled by transistors.

So 64 * 25 = 1.6A
   120 * 20 = 2.4A

That gives me 4000mA and if a standard AA alkaline battery can produce about 2.8 amp hours at 1.5 volts, Im guessing I will have enough power and if  Battery life (hours) = battery mAh rating/battery current
then (2.8 * smiley-cool / 4 = 5.6 hours?
13  Forum 2005-2010 (read only) / Interfacing / Wondering if this is possible/practical? on: November 29, 2010, 02:24:30 pm
Hi everyone, I just received my arduino uno board and am working on a fairly large LED project involving transistors and shift registers powered by a 12 volt 8 aa cell battery pack and before i commit to it, I have a few general questions.

First off, is it possible to connect 6 8 bit shift registers to an uno board with this method of connecting 2 shift regs (http://www.arduino.cc/en/Tutorial/ShiftOut), is there a max number of shift regs you can connect?

Second question, is 12 volts enough to power roughly 184 LEDS with 140 transistors and 324 resistors, and if so how can I calculate how long the batteries would last?
There would be 16 of these: http://www.flickr.com/photos/87989001@N00/4933258821/
which is 64 LEDs running at 25-30 mA

Then there would be the remaining 120 LEDs running at 20 mA

I plugged all this info into a simple LED calculator and got around 2000-2500 mA current draw from the source, not too sure what that means on a scale of battery output, requirement, or battery life.

As a side note, this has been done on a slightly smaller scale with 9 volts using 3 shift regs with 116 LEDs...

Any advice or personal experience in this type of stuff would be greatly appreciated!
Thanks in advance!
14  Forum 2005-2010 (read only) / News / Re: How to pronounce "Arduino" ? on: November 29, 2010, 02:23:19 pm
Now I finally know!
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