Why are the capacitors on the image being used with the DC motor?

For my arduino aplication with L298n is ok to keep or remove them?

enter image description here

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    \$\begingroup\$ related (perhaps duplicate): Why is this capacitor hooked up to a 9volt electric motor? \$\endgroup\$ Oct 31 '15 at 22:02
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    \$\begingroup\$ They help to suppress the high frequency signals that such motors produce. Without these capacitors it would emit a lot more unwanted radio waves when operated. Operate the motor in the dark and you will see sparks inside, these sparks generate radio waves, that's how they did that in the old days. Do NOT remove the caps, they are there for a good reason. \$\endgroup\$ Oct 31 '15 at 22:13
  • \$\begingroup\$ Thank you. But the question is if for an arduino aplication with an L298n do I have to remove them or I can keep them? \$\endgroup\$
    – godolomn
    Oct 31 '15 at 22:16
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    \$\begingroup\$ @godolomn Fundamentally, Arduino has nothing to do with this. \$\endgroup\$ Oct 31 '15 at 22:19
  • \$\begingroup\$ How can you expect anyone to know what they are for besides the person who decided to put them there? Most likely they are there and are needed because something didn't work right without them. If you have a soldering iron, try removing them, but if your stuff doesn't work right, you will have to put them back in. My bet would be that you will need them, so personally, I would not remove them. \$\endgroup\$
    – mkeith
    Oct 31 '15 at 22:50

The caps in your photo are common on commutator type DC machines.Thier purpose isto help EMC because the brushes make lots of electrical noise when the motor is turning .It is quite normal for equipment with such motors like many power tools to fail radiated EMC without them .If you remove the caps its more likely that cummutator hash will find its way into your Aduino causing hassles during debug.OK if you leave them in you do have to be careful about thier charging currents when running say a mosfet PWM buck convertor .The prospective charging currents would make the mosfet run hotter at normal PWM frequencies .The caps wouldnt like the currents anyway.What I do on a buck convertor that drives a motor that may have caps across it is place an inductor in series with the output .For your job 100 microhenry would be good.


Lowers electrical interference. DC motors are usually brushed type and they generate lots of interference when brushes alternate polarity on rotor.


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