DC Motor and noise ...

[voidptr]

I will run 2 small dc motors on a little bot im building ...
i already used standard caps noise reduction , 1 cap (0.1uF) across motor terminals and 2 others from the terminals to the motor casing ...

noise level is not bad but i still can see a bit of it.


is grounding the casing of motor to a common ground with the power battery be a good think / good practice ?, fast silly tests don't seem to show any difference ( im running 2 different sets of batteries for motor and controller ...

im thinkink to have shielded cable to motor this might be where noise spread...

any others good practice, advise ?

 

[misterT]

- Twist the motor leads together.
- Install a toroidal ferrite core on the (twisted) motor leads (near the motor).
- Use shielded cable and ground the shield from both ends.

 

[voidptr]

- Twist the motor leads together.
- Install a toroidal ferrite core on the (twisted) motor leads (near the motor).
- Use shielded cable and ground the shield from both ends.

I saw those kind of cables with core before, but never really thought about them, after few researches and thoughts it makes good sense

I think i have 2 or 3 already made from recycle old junk already

 

[RichTheDude]

Note the shield should never carry current...

 

[Mike odom]

Just seeing the noise isn't a problem... there's only a problem if it interfers with your control circuitry. I did an industrial timer that turned on/off several AC solenoids and had a 1/4hp motor connected to the same power supply that came into my board. I used filters on my power supply to the micro and could put the unshielded board right up against the motor with flawless operation. Here's what I used:

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