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Author Topic: Power LED shield  (Read 7559 times)
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Good news! Still interested of buying 2 when they are ready.

Saves a lot of wire mess, which I hate above all.

I need only two pins (8 PBs in two channels) so I can still connect the display and couple of keys to Arduino.

Jouko
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Hello,

Yes please count me in for 2 boards
Charles
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Who are you using to make the boards and what is the price break?  I am looking to finally start a fairly large project and will need quite a few of these.

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I have built up a nice LED to Fiber Optic Injector that holds the LED's, lenses, luxdrive pucks and fiber connectors.   Basically a big brick that we run on a 3dprinter (in house).  I will post pictures but if you need one I can work out a price either for the brick or the stl file  

Of course I needed this board for this project!    I understand the safety of using the opto isolator but for this project I was just going to connect the Arduino to the +5 ref voltage and the buckpucks to the control.  I am not using PWM, just switching on and off.  There are 4 high power LED's on four separate buckpucks. Per the spec I was going to tie LED negatives all togehter to my ground.    
Any warnings that I am about to blow things up are greatly appreciated.

The Luxdrive spec shows the use of multiple capacitors on the ground and power side but does not suggest a type or value?  Necessary?  

Very many thanks
Charles
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Charles, your project sounds interesting.  What are you going to do with it? (I'm not sure what a Fiber Optic Injector is)  My shield uses the PWM pins on the Arduino, but you don't have to address the pins with PWM.  A digitalWrite() high or low on those pins will function as you should expect, although possibly reversed.

I HIGHLY recommend using the opto-isolator and keeping the uC logic on the Vin side of the puck. (In fact you have to with this shield)  The 5v REF on the pucks can only provide up to 20ma each and you can not combine them in parallel for more current.  It's not enough to power the Arduino.  I fried the 5v REF on two of my three pucks doing this.  Also I've measured between the Vin- and the LED- and they are at different voltages, which varies with the LED current level.  So you must not try to drive the CTL pin directly from the Arduino if the Arduino's GND is tied to the puck's Vin-.  The opto-isolators allow you to do it without hurting anything.  All of this is a primary reason I decided to design the shield - so people could use the pucks safely.  The data sheet doesn't explain it very well.

Yes, the capacitors on the power input are important to keep the transient noise down.  They help the power supply keep up with the switching of the pucks.  And if you are powering the Arduino from the same source, they help reduce noise in the power feed.  I've spec'd one 220uF 50V capacitor PER PUCK on the shield.

Shackscs, I'm ordering the boards from Gold Phoenix (http://www.goldphoenixpcb.biz/), which is where BatchPCB (http://www.batchpcb.com/) sends their panels for fabrication.  If you want a prototype or just a few boards, go through BatchPCB.  For a production run of tens up to thousands, go through Gold Phoenix.

I should be able to sell the PCBs at around $10-13 USD each, plus shipping.  This is just for the PCB - does not include any of the electronics or parts.  However, I'm gathering up the costs for the parts and will post it here.
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I hope this is helpful to your project:
I punched the parts into Digikey
1      1      PS2501-4A-ND      OPTOCOUPLER 4CH TRANS 16DIP            1  1.79000      $1.79
2      1      497-1765-5-ND      IC BUS BUFFER TRI-ST QUAD 14DIP            0      0.48000      $0.48
3      4      490-2907-ND      TRIM POT CERM 5KOHM 25TRN SIDE      5K TRIM POT R1-4      0      0.92000      $3.68
4      4      P12397-ND      CAP 220UF 50V ELECT FM RADIAL      220 uF Cap for Vin Side      0      0.50000      $2.00
5      4      CF1/2330JRCT-ND      RES 330 OHM 1/2W 5% CARBON FILM            0      0.14000      $0.56
      Subtotal      $8.51
So  call it $9.00  without the board cost, IC2 (the power supply) and the LUXDrives.  Luxdrives are approx $15.  (ledsupply.com)  
So a full four channel version of this board is  under $100.
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Nice!  Thanks for running that through Digikey.  I need to do the same with a few different vendors so I get a feel for the range of costs.  I also want to see what I can get with volume pricing.

BTW: I'm hoping to have my shopping cart set up by the time I get these boards fab'ed.  That way I can just direct you guys to that instead of a trying to do a willy-nilly transaction via the forum.  smiley-wink

Also, I have been writing up some documentation.  There are a few optional parts on the board and some other things that can change based on your application.  So I'm trying to get that done as well.  For example, the trim-pots are optional as is IC2 - the voltage reg.  And of course it will be nice if I can provide real instructions for building it as a kit, setting it up and addressing it in code.

I do have one challenge left to solve on the board - clearance between it and the Arduino, especially above the USB port.  I am looking for header pins with a higher clearance than standard.  I've seen them plenty of times before and just need to locate what I have in my head.  This also affects stackability of several shields.  I may have to rev the board design one more time before sending it out to fab.
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I just sent you a PM if you want to see the costs from Mouser.  Modestly higher as expected but I love the ability to save a BOM as a project and re order later.
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Hi,
I am also very interesting in buying one shield. This is really cool.
What should I do to get one of these?
Thanks
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Progress report:

Shopping cart installed.  Needs to be configured.  Will post the link when it's usable.

Found pin headers that solve the clearance problem, but they are EXPENSIVE and don't have sockets on the top, so I'm not happy with them.  Board design may have to change depending on what I find for solutions to this problem.  Posted about it here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1267383978

Got some prices for the bill of materials.  LGM-model has been a great help with that, thanks!  Still getting all my ducks in a row for a kit.

The PCB is close to ready for fabrication.  As soon as I solve the clearance problem, I'll send it out and it should be ready for sale within a few days of receiving them.

Stay tuned!
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Finally what are the pins used?
I have to know If I am buying an arduino mega .. or not. :-)
Thanks
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It's designed for the Duemilanove on pins 3, 9, 10 and 11.  See my first post for all the basic specs.
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Hello,

Are you sure your digital logic is correct as show in the schematic?
I used the signal from Arduino to make the Gate go high/low and the input +5 with the result that the output is inverted...
No?
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The pucks have an inverted input requirement on the CTRL pin: +5v to the CTRL pin will shut off the LED and an 'open circuit' or GND on the CTRL pin will drive the LED at maximum current.

When the PWM signal is HIGH, the opto-isolator clamps the REF (+5v) pin to the CTRL pin, shutting off the LED.  When it is low, the opto-isolator goes open and the potentiometer provides a small voltage from the REF to the CTRL pin to control the current to the LED - and thus the maximum LED brightness.

The easiest way to handle this in your code is to work with it as if there was not an inverted input and then use map() to invert your value right before you analogWrite() it like this:  

ledPWM = map(ledPWM,0,255,255,0);
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Hi,

I have a question about the power source needed.
In the first post, you are saying:
- Input voltage range 5-32 VDC
To drive 2 buckpuck with 6 leds on each (1000mA), can you confirm that my current power source: 24V (2.5A) will match?
Thank you!
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