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Project Help and Ideas » Motor is not getting enough power.

July 24, 2010
by TexanBackpacker
TexanBackpacker's Avatar

Sorry for bombarding the forums with questions, but I have run into a wall with my project. Currently I am messing around with my temperature project and I made it to where if the temp. is above 90 an LED, buzzer, and now a motor with fan on it goes off. Everything is working fine except that the motor is not getting enough power. It needs 1.5V to operate and I'm not sure how much it is getting right now (don't own a multimeter). In order for it to get more juice do I need to add a capacitor to it? Also, if I do what kind do I need to get. (I don't really know capacitors work) Also here is a picture if it helps (it is a little blurry)

http://www.flickr.com/photos/42404810@N05/4824487143/

Thanks

July 24, 2010
by mongo
mongo's Avatar

It loks like you are driving the motor directly from the MCU. Try adding a driver of some sort that is capable of delivering the current you need for the motor like a FET or transistor to do the work. Drive the transistor with the MCU and let the transistor do the work.

Capacitors in te power circuit help with evening out the current for a cleaner power source as well as reducing noise at points of a circuit than have a tendency to generate it. Motors do generate noise but I don't think that is the problem here.

When I did the servo projects, I found that adding a couple of small electrolytic capacitors made the whole circuit much more stable.

July 24, 2010
by hevans
(NerdKits Staff)

hevans's Avatar

Hi TexanBackpacker,

Mongo is right, it looks the problem is you are trying to drive the motor directly from your MCU. While the 5V it is putting out should be enough to drive the motor it probably can't source enough current to drive your motor. You will need to build a circuit to drive your motor directly from the battery (or other power supply), take a look at our motors an microcontrollers video for more on this subject.

Humberto

July 24, 2010
by TexanBackpacker
TexanBackpacker's Avatar

Ok, (I watched the video) so basically a transistor gives the motor a higher current from the MCU witch allows it to run. Will the transistors for sale on the site work fine?

July 24, 2010
by mongo
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The little FETS in the kit should do fine. Make sure you connect them correctly though, as they can burn out if wired wrong.

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