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Topic: Capacitors and motors (Read 1 time) previous topic - next topic

vek11

Hi,
I am trying to build a robot tank with the motor driver Sn 754419ne. So my motor is a 6-12V motor, and I am using a power supply of 6V( 4 AA batteries). So I hear that I should attach a capacitor of 0.1u. My question is what does the capacitor do and how am I supposed to connect it to the motors( Do I connect it to the 2 little terminal on the motor?)
Thanks

Osgeld

I found this, does a better job than what I could explain until I looked it up to reassure myself

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As the motor rotates, there will be positions where the commutator connects and disconnects the motor coils. These will produce sudden changes in motor current (much too fast to measure on a meter) which cause interference to radiate from the motor wires. This would cause crackling on nearby AM radio and could pick up on a nearby audio amplifier.

The capacitor acts like a small reservoir which helps to even out the spikes in current and reduce the interference. It plays no part in the operation of the motor itself, it is there just to kill the interference it creates.


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( Do I connect it to the 2 little terminal on the motor?)


that is where they usually end up too keep the component closest to the problem

vek11

Also, does it matter if I use a ceramic or aluminum capacitor. Because I noticed the ends of the aluminum are different size. And finally, is it mandatory for a motor short term?

Osgeld

you want a ceramic in that situation, and no its not mandatory for hooking up a motor and playing with it

dhenry

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I found this


That was written by people who have never had the chance to put a current probe in there to see what their nice advise is doing, :)

You need a diode there, and if you have to put a capacitor there, put a little resistor there as well (to form a dampening network).

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