Hi All -
I am trying to build my robot drive system using 2 DC motors, one at each front wheel.
I Built 2 identical H-bridges with LMD18201 chips. Purchased some DC motors I got on eBay, they are "Globe Motors - 12V - PN: 125052" @ about $25 ea.
Hooked H-bridges up to an Atmega8 mcu, connected the motors and everything works well EXCEPT the motors run at slightly different speeds.
I determined that one motor was running slightly faster than the other irrespective of what H-bridge it was hooked up to. I tried just about every different type of PWM configuration possible with the Atmega8, just in case, but one motor was always running faster.
So the question: Do cheaper motors often run at different speeds with an identical PWM source? If cheaper motors do often have these problems what quality level of motor, and possibly what brands, will see motors that can run at identical speed / rpms for identical PWM sources?