Subject:
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Re[2]: motors
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 21 Apr 1997 14:48:09 GMT
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Original-From:
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Ericson Mar <emar@csfbg.csfbSTOPSPAMMERS.com>
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Reply-To:
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<emar@&StopSpam&csfbg.csfb.com>
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Viewed:
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1959 times
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Thanks. I tries that. I even tried to use four of them in parralel.
OK, here's what I've discovered...just to let you all in on it and maybe it'll
help someone in the future. I pulled the leads from the motor header and powered
the motors directly from the battery. This yeilded *less* noise. But where's the
other noise comming from? It turned out that my sonar battery was on my motor
base which was aluminum. As I removed the battery furthur from the base, the
noise began to dissapear. It appears as though the aluminum base(which had
direct contact with the motor[probably ground]) was acting like an antenna
causing some interferance??? I'm not entirely sure. I used an osciloscope and
saw the noise from the power supplies, etc. But also, I coonected the
oscilloscope leads to different parts of the metal base and I saw these little
attenuating sine waves. Perhaps that's the source of some EM radiation that is
causing my circuit to got nuts. That's some strong EMI! Perhaps the sonars are
quite sensitive. Well, I'll post the motor model when I get the chance so you
all can avoid buying it. It's a Barber-Coleman something.
______________________________ Reply Separator _________________________________
Subject: Re: motors
Author: PRABAL (INTERNET.PRABAL) at SSWGATE
Date: 4/21/97 5:20 AM
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<335B303D.2F3A@dmsc.com> Date: Mon, 21 Apr 1997 05:15:54 -0400 From: Prabal
Dutta <prabal@dmsc.com> Reply-To: prabal@dmsc.com Organization: Digital Micro
Systems X-Mailer: Mozilla 3.01Gold (Win95; I) MIME-Version: 1.0 To: MAR ERICSON
<mar@cooper.edu> CC: Handyboard <handyboard@media.mit.edu> Subject: Re: motors
References: <Pine.GSO.3.95.970419181232.25324A-100000@zeus.cooper.edu>
Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit
Mar,
You might want to try attaching a small (0.1uF) capacitor to the motor
leads as close as possible to the motor. Use a ceramic or monolithic
ceramic capacitor. That might reduce the motor noise your sonar board
sees. Also remember that even though you are using different power
supplies, they probably share the same ground. Inexpensive toy motors
ofter generate the worst noise, and are the cause of all kinds of weird
behavior.
- Prabal
MAR ERICSON wrote:
>
> Hi,
>
> I have some motor trouble. I have two motors. I have a polaroid sonar.
> When I run one of the motors, the sonar works. When I run the other motor,
> the sonar's detected distance jumps arround randomly. The randomness seems
> to be more at higher speeds. I tried using different motor ports but the
> result is the same. One motor causes this erratic behavior, and the other
> doesn't.
> It's funny, cause the sonar and the motors and the HB are powered
> seperately.
> Has anyone experienced something like this?
> Thanks for any input. :)
>
> -----------
> ericson mar
> Master of Engineering Candidate
> Project: Mobile Robotics
> mar@cooper.edu
> (212)353-4356
>
> Department of Mechanical Engineering
> The Cooper Union for the Advancement of Science and Art
> -------------------------------------------------------
--
Prabal Dutta Tel: (614) 299-2566
Digital Micro Systems, Corp. FAX: (614) 299-2939
PO Box 3579 e-mail: prabal@dmsc.com
Columbus OH 43210-0579 WWW: http://www.dmsc.com
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