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Author Topic: Use digital pins to use a 8-9V Motor ?  (Read 1103 times)
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Hi guys,

I'm making a DIY IR Controlled Car . So for that I've 2 x 8-9V motor .
You understand now what's my problem : digitals pins of arduino nano (or uno, i have both) give just 5 V but I need 8-9 V.
I must use digital pins because i follow this tutorial :
http://www.instructables.com/id/Simple-2-way-motor-control-for-the-arduino/#intro

Thanks guys in advance !

(sorry for my bad english)
« Last Edit: November 21, 2013, 01:08:15 pm by yeko » Logged

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We shouldn't even think of plugging a motor in like that, even if it works on 5v. At a minimum you should control it with a transistor (with a diode across the motor). That won't allow reversal of direction though, so you'll need an h-bridge.

Have a look at small, cheap, controller boards like the Pololu 2130
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Just another of those awful, completely misleading tutorials! Note the disclaimer:
Quote
I am not responsible for any thing bad that happens to you or to your arduino!
(damage to the Arduino is quite likely with 99.99% of motors chosen at random)
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That instructable might teach you why you don't driver motors from logic devices
the hard way - steer well clear of it.  All inductive loads can destroy chips if you don't
make sure you have the right protection circuitry (free-wheel diode, snubber circuit,
etc).

The Arduino cannot supply enough current for all but the most microscopic of motors
without exceeding its abs-max ratings - don't do this!
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Ok thank guys for your answers !
I would use a L293D or the DRV8833 , there is a lot of tuts on google about it .

So thanks for help !
Bye
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Seeing as you have the ability to choose, rather stay away from the 293 and it's larger cousin the 298: they are older technology and wasteful of energy. Go with newer stuff like the 8833 like that Pololu I linked.

Have fun....
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I think to the Pololu but I don't found a tuto to use it .
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You don't really need a tutorial- look at the "minimal wiring diagram" in the Pictures tab....

You supply the motor power across Vin and Gnd as the pic shows: the control is provided by the AIN1/2 and BIN1/2 lines on the left,  the outputs AOUT1/2 and BOUT1/2 to do what you need to drive the motors.

There are 2 motor channels, A and B. Each has 2 inputs, which are digital lines from your Arduino. If you want speed control, at least one of those will need to be a PWM line. You control direction by changing polarity on those 2 inputs. So if say BIN1 high and BIN2 low is clockwise, the BIN1 low and BIN2 high will be anti-clockwise. Pulse either with PWM and you'll get speed control.

Don't forget to join the grounds together.



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Ok the minimal wiring schema isn't hard to understand ! So thanks for that .

But i want to find it on ebay or amazon or another site with low shipping cost because i live in France and i don't want to pay 15$ of shipping fee for a 5$ product (DRV8833) .  smiley

Instead of the L932D on ebay (because it's older)


« Last Edit: November 23, 2013, 02:18:38 pm by yeko » Logged

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So finally i buy a SN754410 on ebay (http://goo.gl/mUuPoV) .

There is a mini-list of Double H-Bridge IC :
- DRV8833
- SN754410
- L293
- L298

Thanks to all !
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I use a sainsmart l293d motor shield. I find it to work quite well, though you need to refer to adafruit for tutorial as there is none under 'sainsmart'.
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The 293 and 298 are wasteful of energy remember. The SN754410  is pin-compatible with the 293, but I'm not sure if it's the same technology?
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For the L293 and L298 you need 2 Capacitors on pins 4,5 and 13,12 compared to the SN754410 that doesn't need it .
That's why there are shields for L293 and L298 with integrated capacitor . It's simply to use .

But how to you know they are wasteful of energy ?
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Because there's always a significant voltage drop across those things. I forget what it is for 293 but the 298 loses 1.8 min, up to something like 4 at higher current. Since that voltage is at a current, that's power, and power times time is energy. Look at pics of a 298 shield and you'll see a heatsink the size of a truck. The 293's middle 4 ground pins are also for attachment to heatsink.

The 8833 may need a heatsink at high current but it's not in the same league.
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I've seen the sainsmart shield but it is compatible with arduino uno (duemilanove and mega) and i've a arduino nano .

JimboZA , can you talk me about the SN754410 ?  (wasteful ?)
« Last Edit: November 24, 2013, 02:12:45 pm by yeko » Logged

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