ElementalVenom
Posts: 3
Joined: Fri May 15, 2015 1:38 am

Controlling a 1.9V motor

Fri May 15, 2015 1:42 am

Hello guys this is my first post so if somethings wrong, tell me. Alright so i have this DV 1.9V motor lying around and was wondering if i could attach it to the pi. I understand the pi supports up to 5v so is there a way to limit the voltage leaving the GPIO pins? I was hoping to do this with the resisters and breadboard i have instead of buying a motor controller.Im very new to electrical work. Any help would be greatly appreciated!

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joan
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Location: UK

Re: Controlling a 1.9V motor

Fri May 15, 2015 7:44 am

You'd have to make your own motor controller. You can get suitable motor controllers quite inexpensively. E.g. this L9910S based one costs 1 GBP http://www.ebay.co.uk/itm/181719397905 from China.

You will need at least a transistor and a diode as well as resistors to be able to safely run a motor under Pi control.

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RogerW
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Location: London UK

Re: Controlling a 1.9V motor

Fri May 15, 2015 8:46 am

If you want to do your own controller you might use one half of an H Bridge chip like this one
http://www.hobbytronics.co.uk/electroni ... r-sn754410

I would suggest you do not use the pi to power the motor. Use an external 2 volt supply. A 1.5 volt battery would probably do for testing.

I have written a python object to drive a motor in this way. It uses joan's pigpio library.

viewtopic.php?f=32&t=110228&p=757085#p757085

Note - I have tested the output from the Motor class using a scope but not in real life.

Roger Woollett

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mikronauts
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Re: Controlling a 1.9V motor

Fri May 15, 2015 2:13 pm

Like others have said, get a motor driver.

You CANNOT drive such a motor from a Pi GPIO pin safely, you will fry that pin, and possibly the whole Pi.

At an absolute minimum, assuming you only need to turn the motor in one direction, you need a transistor or mosfet to switch power to it, and you should have an external power source (if you use the Pi's 3v3 you will reboot the Pi, and possibly damage the Pi's 3v3 regulator, if you use the Pi's 5V, you might reboot your Pi, and you might damage the motor. Cavet Emptor)

A nice dual H-bridge driver is the way to go, for such a small motor, pick one of L9110S, L293D or L298N based module.
ElementalVenom wrote:Hello guys this is my first post so if somethings wrong, tell me. Alright so i have this DV 1.9V motor lying around and was wondering if i could attach it to the pi. I understand the pi supports up to 5v so is there a way to limit the voltage leaving the GPIO pins? I was hoping to do this with the resisters and breadboard i have instead of buying a motor controller.Im very new to electrical work. Any help would be greatly appreciated!
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

ElementalVenom
Posts: 3
Joined: Fri May 15, 2015 1:38 am

Re: Controlling a 1.9V motor

Fri May 15, 2015 11:08 pm

Alright guys thanks a ton. Ive decided to get a L293D for a few bucks and ive also gotten some more powerful motors(5vs).

boyoh
Posts: 1400
Joined: Fri Nov 23, 2012 3:30 pm
Location: Selby. North Yorkshire .UK

Re: Controlling a 1.9V motor

Sat May 16, 2015 3:30 pm

ElementalVenom wrote:Hello guys this is my first post so if somethings wrong, tell me. Alright so i have this DV 1.9V motor lying around and was wondering if i could attach it to the pi. I understand the pi supports up to 5v so is there a way to limit the voltage leaving the GPIO pins? I was hoping to do this with the resisters and breadboard i have instead of buying a motor controller.Im very new to electrical work. Any help would be greatly appreciated!
Put this circuit to gether , using a Zener diode
as a voltage regulator, Might work might not
You said the motor voltage is 1.9v, so could be
low power( watts) When selecting the Zener diode
make shoure the Zener wattage will be ok for the
motor FLC, Use ohms law to calculate the resistor
for the Zener off load wattage ( Zener watts)
Do not use the Pi 5v for the motor side
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BoyOh ( Selby, North Yorkshire.UK)
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