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### Author Topic: Arduino power regulator problems!!!!!  (Read 2545 times)

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#### Hawaii00000

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• Posts: 347
##### Arduino power regulator problems!!!!!
« on: December 20, 2008, 04:34:36 PM »
I recently found a power inverter thingy (or what ever you call) works to power my Arduino off the AC from my house. The problem came when tried to run a DC motor off the 5V power supply. As soon as I connect the motor, the power regulator (I quite sure thats what  it is) starts to heat up real fast. It works perfectly when its powereed by USB but as sson as I plug it into the wall it starts heating up. Does anyone know What the problem is?
MAybe its just normal, I mean its not like its smoking or anything... it just gets really hot.
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#### cosminprund

• Robot Overlord
• Posts: 284
##### Re: Arduino power regulator problems!!!!!
« Reply #1 on: December 21, 2008, 01:59:22 AM »
The wall power adapter you used is rated at a higher voltate (too high). The power regulator regulates power by dumping the difference betwen the input voltage and the output voltage - and this creates heat that's proportional to the dumped voltage and to the used power.

Ex: If you use the USB power supply and an regulator that outputs 5V you're dumping 0V because the USB power supply is 5V. (actually you're loosing some volts because the regulator as a drop no matter what).
Ex2: If you use a typical 7.2V NiMh battery the power regulator will be dumping (7.2 - 5) = 2.2V; That's reasonable (unless your circuit draws a lot of power)
Ex3: If you use a wall adapter that's rated for 12V the power regulator will be dumping (12-5) = 7V. This gives you heat.