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'EMI RADIATED BY A DC MOTOR'
1998\11\04@075223 by Orduyar

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I NEED SOME IDEAS TO FILTER THE EMI RADIATED BY A DC BRUSH MOTOR (12V.)
I want to certificate CE a design but i have a problem with the EMI RADIATED
by the motor.
I have problems with the spec. EN55011, Class A , Group 1 Type : Radiated.
In the frecuency ranges : 30 MHz to 300 MHz I have levels up 30 dB that it
is max. authorized
level.
Somebody know some filter or design for solve this problem?
                       Thanks

1998\11\04@142937 by Harold Hallikainen

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On Wed, 4 Nov 1998 13:40:36 +0100 Orduyar <spam_OUTorduyarTakeThisOuTspamARRAKIS.ES> writes:
>I NEED SOME IDEAS TO FILTER THE EMI RADIATED BY A DC BRUSH MOTOR
>(12V.)
>I want to certificate CE a design but i have a problem with the EMI
>RADIATED
>by the motor.
>I have problems with the spec. EN55011, Class A , Group 1 Type :
>Radiated.
>In the frecuency ranges : 30 MHz to 300 MHz I have levels up 30 dB
>that it
>is max. authorized
>level.
>Somebody know some filter or design for solve this problem?
>                        Thanks
>


       Interesting problem...  Under FCC part 15, motors are considered
"incidental radiators" which must emit as little emi as possible, but
there are no limits.  It gets interesting when an incidental radiator is
combined with an unintentional radiator (such as a PIC).

Harold



Harold Hallikainen
.....haroldKILLspamspam@spam@hallikainen.com
Hallikainen & Friends, Inc.
See the FCC Rules at http://hallikainen.com/FccRules and comments filed
in LPFM proceeding at http://hallikainen.com/lpfm

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1998\11\05@173913 by Tony Nixon

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Orduyar wrote:
>
> I NEED SOME IDEAS TO FILTER THE EMI RADIATED BY A DC BRUSH MOTOR (12V.)

I would have thought a suppression cap across the motor terminals would
have sufficed.

--
Best regards

Tony

Multimedia 16F84 Beginners PIC Tools.

http://www.picnpoke.com
Email picnpokespamKILLspamcdi.com.au

1998\11\06@020742 by jlepine

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The cap won't do much if the power leads are "antenna length" at the
frequency of interest.  A choke in each line will be more help.

Tony Nixon wrote:

{Quote hidden}

1998\11\06@043658 by

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{Quote hidden}

1998\11\06@105819 by Richard A. Smith

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On Fri, 6 Nov 1998 09:24:24 -0000, Rigby-Jones, Michael [PAI01:4837:EXCH] wrote:

>> Most cheap RC toys I have seen use 3 caps, one across the two terminals
>> and one from each terminal soldered to the motor case, and sometimes a
>> choke in each line as well.  I guess this is a consequence of the cheap
>> and nasty RX circuit desgin having zero noise immunity.
>>

I had to solve this on some motors on a tennis ball throwing machine.  The above
cap configuration was used with the addition
of a large inductive choke in both power wires as close to the motor leads as po
ssible. (A torroid that we wound the wires
around.)  We just tried cap values until we found the best values to use.  One k
ey is to make the capacitor leads as short as
possible to keep the lead inductance low.  And make sure that the cases of the m
otors have a GOOD path back to ground.
We cut our emmissions by some thing like 80% or 90%

>>       > Orduyar wrote:
>>       > >
>>       > > I NEED SOME IDEAS TO FILTER THE EMI RADIATED BY A DC BRUSH MOTOR
>> (12V.)
>>       >



--
Richard A. Smith                         Bitworks, Inc.
@spam@rsmithKILLspamspambitworks.com               501.521.3908
Sr. Design Engineer        http://www.bitworks.com

1998\11\19@143615 by jlepine

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The cap won't do much if the power leads are "antenna length" at the
frequency of interest.  A choke in each line will be more help.

Tony Nixon wrote:

{Quote hidden}

1998\11\20@070833 by Tony Nixon

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Orduyar wrote:
>
> I NEED SOME IDEAS TO FILTER THE EMI RADIATED BY A DC BRUSH MOTOR (12V.)

I would have thought a suppression cap across the motor terminals would
have sufficed.

--
Best regards

Tony

Multimedia 16F84 Beginners PIC Tools.

http://www.picnpoke.com
Email RemoveMEpicnpokeTakeThisOuTspamcdi.com.au

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