What caps for 7.2V DC motor?

Hello, I just purchased four (6mm shaft) 7.2V gearhead motors for an ATV robot project. Just wondering what caps I need across the motor's positive
and negative terminals? Is they a way to calculate this for furture reference?
Thanks Richard
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Couldbeflying wrote:

Not possible to know without knowing your motor's inductance and resistance.

The capacitor will resonate with the inductance, and the ringing will be damped by the motor's resistance. If it has very low resistance, you'll need to add a resister, usually in series with the cap. The objective is to ensure that the ringing is at a frequency where it will cause minimal problems of getting into other circuits, and to damp it out as quickly as possible consistent with not losing too much efficiency in your drive circuit.
Google for some tutorial on damped tuned circuits and you'll get the idea quickly.
Clifford Heath.
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