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Author Topic: sharing the usb power from my intuos 3 a4  (Read 2855 times)
chimalli
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« on: May 22, 2012, 07:14:01 PM »

I'm not sure if i can share the power coming from my pc to my intuos a4 via USB to power an external fan, will this effect my intuos 3 a4. I'm just afraid i'll short my intuos somehow and ill have to buy another one and rightnow moneywise things are looking kinda bleak. Neway any info on this would help.
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bernard
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« Reply #1 on: June 02, 2012, 01:19:14 AM »

how much mAmps is the fan?  What voltage is it running on? USB is 5 Volts.

The short answer is no.  Now for the long answer:

The "electrically safe" alternative is to get a cheap self-powered USB hub, get one of those "red" USB "power" connectors cables and hook your fan to the power pin. USB is 500mA max. Count about 100 mAmp for your tablet -- maybe a little more -- let's say 150mA.  Now add the usb hub mAmps (you cannot know that really, so let's count 100mAmp). And then add your fan's mAmp.  It must not go over 500mA total since this is the maximum a USB device can ask for on one USB port. Your laptop might actually refuse it and will not let power through (USB devices only have 100mA garanteed).  The red power might try to acquire a full 500mA alone thought.  The alternative is to use a Teensy board and program it to ask the exact amount that you require to the laptop.

The "non-safe" approach is to hook your fan directly. It won't short anything, your laptop might not like it (pulling more juice than advertised) and shutdown the USB port.  On the other hand, the laptop might not even look at it and it might just work. Just don't overload your USB ports because you are essentially doing this power management "yourself".

Preferably find a 5V fan. If it is 12v it will just run quieter (slower) or not run at all.
« Last Edit: June 02, 2012, 01:43:35 AM by bernard » Logged
chimalli
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« Reply #2 on: June 02, 2012, 06:22:16 AM »

thx, i found out mine is the intuos 3 ptz-1231-w and i checked the back and its uses 300mA so if I find a fan thats 5v and under 200mA, i've found some stuff on ebay and dealextreme but they dont put all the information(mA, volts etc..)thx for the help now i can start building and planning for the shape n stuff
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