[dorkbotpdx-blabber] ARRGGHH - Please check this circuit

[Hans Lindauer]

By now, many of you have been blinded by my MIDI LED project at the 
meetings.  Hopefully some of the electronics experts out there can help 
me get this thing working so I can get on with my life.

The trouble is, I've been trying to run the whole thing off of 5V, but 
when the lights come on fully, it /appears/ (I don't have a scope to 
confirm this) that the voltage drops below the minimum for the 
microcontroller, causing the microcontroller to reset.

I had hoped that putting a capacitor on the microcontroller's power rail 
would help (I even figured out to put a diode going into the cap), but 
it still isn't working.  I think the problem is that 5V doesn't provide 
enough overhead, and trying to use caps to take up the slack is only 
going to be marginal at best if I want to be able to run the LEDs at 
full brightness (which I do).

So my next step is to try powering it off of 12V instead of 5V.  
/BUT.../ when I tried that before, it burned out my LED after a few 
minutes (and I can't afford to burn out too many of those, they're 
expensive).  The guy who posted the driver circuit I'm using claims that 
it works for 3V-60V, but obviously I've found an exception to that.

I don't understand this stuff enough to know what's the problem here, 
but if any of you do, could you please let me know what to try next?  
And if there's a Better Way (that won't break the bank or introduce a 
lot of complexity), I'm open to suggestions.


Here's the driver circuit; I have 36 of these in the system, hooked up 
to the Dorkboards' PWM outputs:

I=1A thru the LED (metered at 5V input)
R1=100Kohm, 1/4W
R3=0.56ohm, 3W
Q1=Fairchild 2N5088BU Small Signal NPN Transistor  data sheet 
<http://www.fairchildsemi.com/ds/2N/2N5088.pdf>
Q2=Fairchild FQP50N06L 60V N-Channel QFET Logic Level MOSFET  data sheet 
<http://www.fairchildsemi.com/ds/FQ/FQP50N06L.pdf>
LED=LedEngin LZ4-20MA10 Hi-Power LEDs on MCPCB RGBA 10 Watt Full Color  
data sheet <http://www.ledengin.com/products/10wLZ/LZ4-00MA10.pdf>
(I'm not using the amber die on the LED)
Link to Instuctables page for this circuit 
<http://www.instructables.com/id/ECM4Q6NH9IEWOF32MJ/>



Thanks!
-Hans
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