Motor Shield Problem again I think

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Soelen
 
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Motor Shield Problem again I think

Post by Soelen »

Hello,

my name is Soelen, and I started to develop with the arduino shield silly stuff just a few weeks ago. For a few days I finally completed the motorshield but.... a problem appeared which I do not understand, because it is so hard to explain, I recorded my problem by video and uploaded it short just to demonstrate. Feel free to use MouseWheel to move for or backward in this video:

http://flashcrack.org/motorshield/

This is a 4,5 Volt motor. 60 mA and I first used 2 x AA Batteries on it. I got not the full power of the motor but hey! It is working. After that I tried to same but with the motorshield + arduino, which the power comes from the usb port. As you can see in this video it is working but just by a light touch it's stopping because... it has not enough power for some reason! (That doesnt happen if I do the same with the Batteries but there I do not have this problem). Even using a 12V AC Adapter fails. Same speed and something is humming... I think it is the motor...

the speed is set to 255 and as I said I tried it with a 12 V Adapter....

What is my problem? I hope someone can help....

thanks in advance, soelen

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adafruit_support_bill
 
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Re: Motor Shield Problem again I think

Post by adafruit_support_bill »

This is a 4,5 Volt motor. 60 mA
Is that a no-load rating? I would expect that motor & geartrain would need more than 60 mA. Do you have a meter to measure the actual current in use?

What is the rating on your 12v supply? And how do you have it connected?

Soelen
 
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Joined: Thu Nov 18, 2010 9:43 pm

Re: Motor Shield Problem again I think

Post by Soelen »

I tried to mess A, but I think I am just messing it wrong because I just get no values... ohhh why did I forgot everything? D:

could you please explain me how to mess with a multimeter?

also I do not understand what do you mean with 12v supply, maybe an ac/dc adapter? I connected it first with 2 x aa battiers and after that with an usb cable.

regards, Soelen

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adafruit_support_bill
 
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Re: Motor Shield Problem again I think

Post by adafruit_support_bill »

Here are some tutorials on multimeters: http://www.adafruit.com/index.php?main_ ... torials#28
I do not understand what do you mean with 12v supply
I mean the 12v adapter you tried. Does it have any rating for how many milliamps (mA) it can supply at 12v?

Soelen
 
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Joined: Thu Nov 18, 2010 9:43 pm

Re: Motor Shield Problem again I think

Post by Soelen »

Thank you for helping arduwino, unfortunately those links conains Voltage, Ohm and Continuity but no Ampere.

The 12v adapter says 300mA max, I hope this is helpful

and I still dont get how to mess ampere, there are just unuseful Videos on Youtube.... but since I can mess Ohm, I could calculate that on paper Ithink, I am going to try that out

Regards Soelen

Edit: Ok by using 3 x AA battiers so 4,5 V, and plugin in on my motor I get .902 Ohm if I did nothing wrong, so... it is 4,89 Ampere by using the U R I Triangle?

Regards Soelen

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adafruit_support_bill
 
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Re: Motor Shield Problem again I think

Post by adafruit_support_bill »

unfortunately those links conains Voltage, Ohm and Continuity but no Ampere.
Sorry about that. :oops: This site shows how to do current measurements also: http://www.doctronics.co.uk/meter.htm

Ohm's law alone is not going to help you with motors. Al sorts of other factors come into play when the motor starts spinning. It is better to measure the actual current with the motor in use.

Try to get a reading with no load (just spinning the treads as you showed in the video). And also a reading under load (some resistance to make the motor work harder). You can also check the 'stall current', by adding enough resistance to stop the treads from moving. But don't hold it for more than a couple of seconds or you could damage the motor.

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