Noise suppression - Capacitance
 

On most of the motors we get for 1/16 there is a capacitor attached to the motor in either of a few configurations to reduce noise.

For bigger motors (12 V drill motors)....what size does the capacitor have to be be ? Or can i t be the same as for the smaller motors?

And if the motors are bidirectional - does that make a difference?

And what is the best configuration? Across the positive/negative termonals? From one terminal to the case of the motor?etc etc etc etc etc....

I searched....but most sites Ifoundjust link out to some super technical information on a university website or whatever and that aint helping.....
p</p>

RE: Noise suppression - Capacitance
 

Answer to some of your questions:

Direction of motor no difference.

Capacitor sizes are a calculated value based on many motor characteristics to 'tune' a tank circuit. But to be simple something in the 50-100 pico-farad range should work.

Configuration should be two caps, one + terminal to case and second - terminal to case.

RE: Noise suppression - Capacitance
 

Hi heavyasleadThatnks for the input.The reason I ask about a bidirectional motor is that when I went to ebay....some of the capacitors are "polarised" which to my mind means they must hav a +ve and -ve connection or end.So will they work with a bidirectional motor (where +ve and -ve preumably switch depending on direction)?Or am I missing something fundamental here?p

RE: Noise suppression - Capacitance
 

I believe what Heavy was talking about above was making a bipolar cap referenced to ground by the middle two legs out of two polar caps such as electrolytics. If you do that the caps will see reverse voltage at some point so you will have to be mindful of the breakdown voltage.I would use a non-polarized cap such as a ceramic disc type. They are easier to fit against the motors anyway.I don't think this is the best application for electrolytics.

At least I think

Perry


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RE: Noise suppression - Capacitance
 

you can also fit these

i have tidied up the amount of "Bare" wire showing please dont do the same as the picture as you will get a dead short and damage something
http://i418.photobucket.com/albums/p...ndtiger005.jpg

these came off a 1/16th Abrams and are excellent at reducing the whine from the Motors to board and speaker

also twisting the motor cables as much as you can also inhibits the whine ;)

RE: Noise suppression - Capacitance
 

What are the specs on those?

RE: Noise suppression - Capacitance
 

Hi AFV342What are those ? I dont recognise them....Could you post a diagram of wher they are joined to exactly?Hello PerryS"I believe what Heavy was talking about above was making a bipolar cap referenced to ground by the middle two legs out of two polar caps such as electrolytics. If you do that the caps will see reverse voltage at some point so you will have to be mindful of the breakdown voltage. I would use a non-polarized cap such as a ceramic disc type. They are easier to fit against the motors anyway. I don't think this is the best application for electrolytics."I honestly didnt understand very much of that at all!p

RE: Noise suppression - Capacitance
 

Don't use electrolytic capacitors (usually polarized), use ceramic type (disk shaped and non-polarized).

It's rare that motors in this size would require electrolytic type capacitors, usually 1/5 horse power and above may require these.

RE: Noise suppression - Capacitance
 

Usually they are of .01 or .1 MICRO-farads

RE: Noise suppression - Capacitance
 

Things are a little clearer now.......

So, and correct me if Im wrong.,....... Ineed a .1 microF ceramic capacitor.

If I solder one between the two motor leads/contacts, and one between each of the motor leads/contacts and the body of the motor...... then Im good to go?

One more question.......the motors Ihave have a kind of tight fitting metal sleeve around the body.

Has this any particular function other than keeping crap out of the motor?

Should I solder the capacitors to the sleeve or the actual motor casing?

p

RE: Noise suppression - Capacitance
 

That is essentially correct. If the noise is still present then different value capacitance is needed.

The sleeve about the motor could likely be a stator ring (basically helps increase torque by concentrating the magnetic field).