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Is there a good way to get the ArduinoMega2560 to output 0-15 volts?  Our motor needs at least 10 Volts to spin at the speed we need and a smaller motor wont work due to the load we are trying to spin.  We have tried a MOSFET and it keeps blowing the IC.  The only answer we have come up with is to put a 7.5 volt battery in series with the 5 volt output from the arduino board. 

Any ideas?
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The MOSFET and an external power supply is a good idea.  You will need a MOSFET that can handle the voltage and current.  Expect a fairly large current spike when starting the motor from a stop.  Put a diode across the motor to absorb the "back EMF" of the motor windings.
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Is there a good way to get the ArduinoMega2560 to output 0-15 volts?  Our motor needs at least 10 Volts to spin at the speed we need and a smaller motor wont work due to the load we are trying to spin.  We have tried a MOSFET and it keeps blowing the IC.  The only answer we have come up with is to put a 7.5 volt battery in series with the 5 volt output from the arduino board.


Any Arduino output pin can only output 5vdc at low current. To power a motor you need to power it with a external DC power supply sized for the voltage and current requirement of the motor. A transistor is then used to control the motor and the arduino controls the transistor.

First you need to tell us the normal voltage and max current rating for the motor, otherwise any specific recommendation would just be guessing.
  

Lefty
« Last Edit: February 22, 2011, 08:27:07 pm by retrolefty » Logged

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Sparkfun has a logic level MOSFET for ~$1 that might work for you.

http://www.sparkfun.com/products/10213
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That SparkFun MOSFET is a good choice.  I think it's the same one that Makerbot uses in the Extruder Controller.

Note that even though the MOSFET is rated or 30A it will only do that with a good heatsink.  Without a heatsink it will overheat at about 2 or 3 amps at 12v (24 to 36 watts) and shut itself down.  Fortunately the shutdown is just a protective measure and if you turn off the power it will reset.  It also has a built-in diode to protect against back-EMF from an inductive load.  They are hard to kill, which is good for experimenters.
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Without a heatsink it will overheat at about 2 or 3 amps at 12v (24 to 36 watts) and shut itself down.


Could you expand on this 'automatic' feature you are talking about?

 It's been my experience that it is very easy to destroy power mosfets by forcing them outside their SOA (safe operating area). Manufactures go to great detail in their datasheets to explain the limits and the need to avoid them.


Lefty

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the datasheet  mentions nothing of current or thermal shutdown. im pretty sure if you push this mosfet too hard it will blow up, not shut down. perhaps you are thinking of a 7805 or some other nicer mosfet.
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http://www.onsemi.com/PowerSolutions/product.do?id=NID5004N

those ones are current/ thermal protected.
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http://www.onsemi.com/PowerSolutions/product.do?id=NID5004N

those ones are current/ thermal protected.

You're right.  I got the two confused.  The ON Technology one is the kind used in the Makerbot.
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