Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: ChrisK on July 10, 2008, 05:17:16 PM

Title: Motor Driver Circuit
Post by: ChrisK on July 10, 2008, 05:17:16 PM

Hey there guys.  i have recently gotten interested in Robot design and thought you guys could help me out.  I have designed (hopefully) a motor driver using an l293 H-Bridge.  It's basically just the H-bridge and some resistors and capacitors to help filter out some noise.  I was hoping that you guys could give me some advice on my design and if I have made any mistakes or anything.  Thanks.

Schematic:www.chriskeathley.com/motor_driver_schem.bmp (http://www.chriskeathley.com/motor_driver_schem.bmp)

Title: Re: Motor Driver Circuit
Post by: paulstreats on July 10, 2008, 05:36:11 PM

Hi,

 It looks okay to me,

 Some people add diodes at the motor connections (I usually dont myself but if youre building for a long time project or a commercial unit then they are worth considering). This is to protect the driver chip because when motors change directions or stop etc, the magnetic field breaks down and can back up into the chip again (which might get damaged), the diodes direct the power away from the chip and into the battery or power bus allowing it to be re used instead of being wasted and possibly smoking youre driver ic.

 See this website for a better explanation: http://www.robotroom.com/HBridge.html (http://www.robotroom.com/HBridge.html) He's using a different motor driver but the principles are the same. Obviously you need to select your diodes to be able to handle your own motor requirements.

Title: Re: Motor Driver Circuit
Post by: BANE on July 10, 2008, 06:56:25 PM

I don't know how much your circult is going to cost or what voltage your handling but i was going to built my own from scratch until i found this one.  I've been happe with it ever since :).
http://www.robotshop.ca/home/products/robot-parts/motor-controllers/brushed-motor-controllers/all-brushed-motor-controllers/solarbotics-l298-motor-driver-kit.html (http://www.robotshop.ca/home/products/robot-parts/motor-controllers/brushed-motor-controllers/all-brushed-motor-controllers/solarbotics-l298-motor-driver-kit.html)
Bane

Title: Re: Motor Driver Circuit
Post by: Webbot on July 10, 2008, 09:39:10 PM

Have you checked out my tutorial at http://www.societyofrobots.com/member_tutorials/node/159 (http://www.societyofrobots.com/member_tutorials/node/159)

Gives a number of alternatives for power, voltage etc