Continuing with my foray into the world of motors, after having examined stepper motors, I thought I would take a look at D.C. geared motors, which are often used in the cheap wheeled robots that you see on eBay…
A closer look
This is one of the cheap Chinese motors on eBay
These are often used in the SparkFun wheeled robot clones
The axis can be straight/inline with the motor rotor, or at 90 degrees in order to save on width, and reduce the width of the vehicle.
These yellow motors are a popular motor, but superior motors are available.
A video review on eBay motors, especially the Chinese clones. This video is not strictly about steppers, although they are mentioned, it is more about geared motors: