Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: BuddingContraptionist on November 20, 2008, 06:36:51 PM
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i think i want to make a wheeled contraption... where can i buy good robot motors? I found this motor (http://www.sparkfun.com/commerce/product_info.php?products_id=424) at sparkfun, which nicely matches this gearbox (http://www.sparkfun.com/commerce/product_info.php?products_id=319). But that's the only motor and the only gearbox they sell. Where is a good place for motors? (and on a semi-related where-do-i-find-this-stuff note, anyone know where i can find one of these JST connectors (http://www.robotshop.ca/lynxmotion-sirc-04-cable.html) for the sharp IR range finder? i got a rangefinder but forgot to get that cable and i dont want to order just one thing all the way from canada)
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http://www.trossenrobotics.com/store/p/5447-GP2D12-Sharp-IR-Sensor-to-Servo-Cable.aspx
You can also get motors from the same place.
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(and on a semi-related where-do-i-find-this-stuff note, anyone know where i can find one of these JST connectors (http://www.robotshop.ca/lynxmotion-sirc-04-cable.html) for the sharp IR range finder? i got a rangefinder but forgot to get that cable and i dont want to order just one thing all the way from canada)
See other forum posts re connecting directly to the sensor without using a connector
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is it bad for a motor to run it at a lower voltage than it's rated at? like if i get one that's 12v, but use a 9v battery to run it?
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solarbotics sell lots of different motors, many with gearheads already attached
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is it bad for a motor to run it at a lower voltage than it's rated at? like if i get one that's 12v, but use a 9v battery to run it?
No problem for a DC motor. Reducing and increasing the DC voltage is exactly how speed control is attained. So running a 12V motor at 9V just means that it will run slower with less torque.
Given that, let me say that running a motor with a 9V battery will drain that battery very quickly unless that motor is really small.
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Running a motor at a lower voltage won't break anything, but as ArcMan said, it will have lower torque/speed.
Reducing and increasing the DC voltage is exactly how speed control is attained. So running a 12V motor at 9V just means that it will run slower with less torque.
Given that, let me say that running a motor with a 9V battery will drain that battery very quickly unless that motor is really small.
A motor is most efficient at the rated voltage - meaning a higher torque/joule ratio. So less wasted battery energy, basically.
But the proper way to control motor speed is through PWM, which is like turning the motor on/off really fast so that it reaches some medium speed.