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Flush PowerMac Mod

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So you have enough PWM channels on the Arduino very cool.
Just briefly looking the specs its only 40ma per I/O pin.
And you need 600-750ma to drive the fan.

How are you going to increase the forward current for each channel? Just curious.

Its a great and very elegant solution. I don't have a arduino, but, this could be perfect excuse to get one.
 
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How are you going to increase the forward current for each channel? Just curious.

With some form of high-side drive transistor, see here around half way down for an explanation.
All the below use P-Channel Mosfets

PWM:
1784Fig08b.gif

Linear Drive:
1784Fig08d.gif

DC-DC (Switchmode):
1784Fig08f.gif


So switchmode is ideal, but I can't find enough documentation to comfortably build something.
When the arduino arrives, I'll see if I can power the control pin with a PWM output as above


I haven't heard of level switching before as I've always dealt with ground control, so I'm a little out of my depth at the moment!
This explains it simply
 
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