DC motor noise

Okay i built this robot the servos and controller boards are on a different power supply then the DC drive motors, the problem i am having is that the motors are getting so much electrical noise that they jerk forward and on and off. I have placed 1F ceramic disk capacitors from both motor terminals directly to the motor case. This works but then stops working and i continues to work every so often. I even tried twisting the motor wires together in hopes of that reducing noise. It is the same for both motors. I have even tried larger capacitors which worked for a few minutes but then started getting interrupted again by signal noise.

At first i thought all of this was a power issue so i upped the battery to a 9.6V 600mA Ni-Cad and wired up 2 larger DC printer motors which worked perfectly. But they are to large to implement into my robot without a complete design change. which would pretty much be a restart from scratch. since my body design is pretty permanent. All parts are replaceable but the case can not be made larger to house a bigger motor.

I just cannot seem to get rid of this electrical noise long enough. I have taken the bot apart about 4 times now in a row to try something else.

These are the motors that i need to get working. http://www.pololu.com/catalog/product/604

Well turns out that cheap DC motors produce allot of electrical signal noise that causes them to spazz out. So by adding a 1Farad ceramic disk or polyester film capacitor across the motor leads will suppress the signal noise.

Turns out this is a pretty common discussion on some of the other arduino and electrical forums out there... for getting 31 views i kind of figured someone would have mentioned that.

Now the little robot is moving forward but has since encountered a broken tooth on one of his drive gears....ugh

So by adding a 1Farad ceramic disk

I don't think you did, it would be the size of a football pitch (ceramic disk type). You might have added a 0.1uF that's 0.00000001 Farad

See:- http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

I don't do weekends

You might have added a 0.1uF that's 0.00000001 Farad

You've got an excess zero in there Mike - 0.1uF is 0.0000001Farad

Hello, Found this thread and thought it may related to the problem i am having. I am not using the same motor that Tlavite is using. I am using a Vex continuous motion servo. I am, however, experencing very similar erratic and noisy issues with it. My post is http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1241788087/6#6

i would appreciate any input or feedback you may have in this regard.

Thank you!

Andres

Let us reiterate - have you tried decoupling?

http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Let us reiterate - have you tried decoupling?

Yes Mircho. I read the article and understand the need for the capacitors in my circuit. My only issue is that i am not quite sure how i need to connect them to my setup.

Being that i am not using a dc motor but a servo with three connectors (ground, 9 volt, and signal) i do not know to which of these, if not all, do i need to add the capacitors to.

In addition, i do not know what capacitors would be needed for my setup. I am currenlty feeding this servo 9 volts from the Vin pin (using an external power supply a 9 volt with 1000 milliAmp) The servo's power range is from 5.5 volt to 9 volt.

Lastly, how do i exaclty connect the capacitors? if the capacitors required are not polarized, do i need to have one if its pins set ground and the other in between the connectors?

i am going to continue playing with my setup to see if i have any luck... if i do, i'll be sure to post it here as well as my original post. In the meantime, i would be glad to receive any feedback you may have.

Thanks!

Andres

OK so you have tried decoupling but you don't know how to wire it up. I would suspect that you haven't tried it. If you have tried it and it has not made a difference then you do not have enough decoupling.

There is no difference as far as decoupling is concerned between a DC motor, servo motor, relay or any other load.

Lastly, how do i exaclty connect the capacitors?

Well one wire goes to the ground and the other to what you want to decouple, like the relay coil, or the load. You might need more than one capacitor, or and resistor and capacitor or an inductor. Have another read of the web page.

OK so you have tried decoupling but you don't know how to wire it up. I would suspect that you haven't tried it. If you have tried it and it has not made a difference then you do not have enough decoupling.

Not succeeding the first time does not mean that one did not try... it just may mean that you did not get it right that time :) I simply stated that because it did not work for me that time, i was pretty sure i did not know how to wire it correctly.

In any case, i continued tweaking the circuit and finally found a solution to the problem. In deed, Decoupling was the the solution... and wiring it correclty made it happen!

My problem was that, for some reason, i thought that i had to add a capacitor to the servo's ground connection. after i removed this capacitor and left the one for the signal connection, my device stopped its erratic behavior. The servo ran ONLY when i sent it the appropiate command.

Thanks to everyone who provided help and support... i think that's the main stregth of this forum: the fact that there are many, more knowledgeable users, who are willing to take the time and help noobs like me even though we may not exactly know what to ask or how to word the questions correctly! Thanks again!!

Not succeeding the first time does not mean that one did not try... it just may mean that you did not get it right that time

Yes sorry what I was trying to say was that you might think you have tried it but you haven't.

Glad we were able to help. When you think about it what we are doing is so physical and practical that it is amassing that we can get very much over to people just by using words. I do appreciate that it is difficult to know the right words to use when you are a beginner and especially if English is not your first language. Having said that words are important in conveying both problems and solutions and sometimes one has to "read between the lines" to try and understand what is meant rather than what is being said.

Anyway glad you got your system working, onwards an upwards to your next problem, that's what makes this business rewarding and frustrating in equal measures.