Noise filtering capacitor on DC motor

[mwtse]

Just wonder what capacitance should be used to filtering off noise from the carbon brush of a small DC motor that is typically used in toys.

I have a robot project and is trying out different motor/gear sets. Some motors come with capacitors but most do not and I've seen different capacitance were use, is it always the larger the better?

[crazybillybob]

Here's a link to Kronos Robotics (http://www.kronosrobotics.com/an142/GAN142.shtml), Mike has a great article on how to suppress motor noise.

Good Luck,
CrazyBillyBob

[Aud1073cH]

I've seen some smaller capacitors on a couple of toys. - Just make sure the voltage rating can handle more than the motor voltage (double is probably safe). Sometimes these electro/magnetic/mechanical things can generate a back voltage when you shut them off, - from the collapsing EM field.