Author Topic: DC motors with Axon  (Read 3521 times)

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Offline HanoushTopic starter

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DC motors with Axon
« on: February 07, 2009, 12:32:42 PM »
I am building a Quadcopter and I was wondering if I can connect my Axon directly to the "DC motors" using "PWM" and without using "H-bridge" or "motor controller" ??
can this be done ?

Offline Razor Concepts

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Re: DC motors with Axon
« Reply #1 on: February 07, 2009, 12:37:45 PM »
Most likely not, since the pins can only put out like 20-40ma, and your motors will most likely draw more power than that. One option is to just use a brushed ESC for airplanes which you can connect directly to the Axon.

Offline horo333

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Re: DC motors with Axon
« Reply #2 on: February 07, 2009, 12:39:35 PM »
yes, i use DC motors for my robot, you just plug them in, and...use the breadboard, not the pc com...there is no solderin'
like robots, not u

Offline TrickyNekro

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Re: DC motors with Axon
« Reply #3 on: February 07, 2009, 12:57:03 PM »
NO THE HELL NO!!!! PLEASE!!!!

You are gonna burn the pin for sure.... when it is written that these pins can output 20mA means that if there is a larger
current draw then.... good bye happiness....

And it's sure that a DC motor will draw more than 20mA due to very low internal resistance....
Use an H-bridge.... No question about it....

Are these things RC motors???
My speed 400 with a fan draws about 11A from the supply!!!! So you are going to need Mosfets.... if so...
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline horo333

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Re: DC motors with Axon
« Reply #4 on: February 08, 2009, 07:23:32 AM »
ok, can you tell me where to buy the H-bridge, or motor driver, and...what's better ? ;D ;D ;D
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Offline Webbot

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Re: DC motors with Axon
« Reply #5 on: February 08, 2009, 12:11:42 PM »
You can get them from lots of places. Google.

www.DimensionEngineering.com, solarbotics amonst others. Or you can make your own. But before you start - you need to know how much current your motors need.
Webbot Home: http://webbot.org.uk/
WebbotLib online docs: http://webbot.org.uk/WebbotLibDocs
If your in the neighbourhood: http://www.hovinghamspa.co.uk

Offline horo333

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Re: DC motors with Axon
« Reply #6 on: February 08, 2009, 01:01:28 PM »
like robots, not u

Offline horo333

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Re: DC motors with Axon
« Reply #7 on: February 08, 2009, 01:02:58 PM »
i don't see where to put my motor wires(there's only two +, -)
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Offline Webbot

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Re: DC motors with Axon
« Reply #8 on: February 08, 2009, 01:10:09 PM »
Its NOT a motor controller - its a power supply !!!

That website has various motor controllers for 5 amps and greater:
eg http://www.dimensionengineering.com/Sabertooth2X5.htm

But - and I repeat what I said earlier. You NEED TO KNOW HOW MUCH CURRENT your motors will need. It could be anything from a few 100mA up to 10's of Amps.

So a cheaper motor controller that can supply less power is : http://www.solarbotics.com/products/k_cmd/
Webbot Home: http://webbot.org.uk/
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Offline horo333

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Re: DC motors with Axon
« Reply #9 on: February 08, 2009, 01:40:05 PM »
im buyin' new servos, bye-bye waries ;D ;D ;D
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Offline HanoushTopic starter

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Re: DC motors with Axon
« Reply #10 on: February 09, 2009, 03:13:52 PM »
Thanks a lot guys, I am thinking to put a relay before my motor & send PWM signal to it.

Offline Admin

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Re: DC motors with Axon
« Reply #11 on: February 09, 2009, 09:47:03 PM »
Thanks a lot guys, I am thinking to put a relay before my motor & send PWM signal to it.
A relay will require like 200mA . . . still won't work.

Since you are making a quadrotor, you don't need a full motor driver. Your motors will only spin in one direction unless you want to do crazy tricks with it.

All you need is a single NPN MOSFET per motor. Attach the Axon PWM pin to gate, attach the source pin to ground, and the drain pin to your motor. The other wire on your motor attaches to battery power.

Make sure the MOSFET you get is rated for the voltage/current your motor uses. You can buy one at mouser.com for about ~$3 each. Solder it all onto a protoboard.


You can find motor drivers and everything else here:
http://www.societyofrobots.com/robot_parts_list.shtml

Offline HanoushTopic starter

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Re: DC motors with Axon
« Reply #12 on: February 10, 2009, 04:36:45 AM »
I was thinking about buying this :
http://www.robotshop.ca/solarbotics-l298-motor-driver-kit.html
I will get one for every 2 motors,so that can save me some weight.

Offline Admin

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Re: DC motors with Axon
« Reply #13 on: February 10, 2009, 05:03:44 AM »
I was thinking about buying this :
http://www.robotshop.ca/solarbotics-l298-motor-driver-kit.html
I will get one for every 2 motors,so that can save me some weight.

That will work . . . but all you need is just a single MOSFET per motor . . . it'll be the size, shape, and weight of a voltage regulator . . .

Offline HanoushTopic starter

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Re: DC motors with Axon
« Reply #14 on: February 10, 2009, 05:30:28 AM »
Yea But I think I will need a Breadboard for it.

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Re: DC motors with Axon
« Reply #15 on: February 10, 2009, 11:37:53 AM »
Nah no breadboard, just get the 'PC board' such as for my $50 Robot:
http://www.societyofrobots.com/step_by_step_robot_step3B.shtml

You can then saw off parts of it to reduce size/weight.

 


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