Post by thread:EMI RADIATED BY A DC MOTOR

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

On Wed, 4 Nov 1998 13:40:36 +0100 Orduyar <spam_OUTorduyarTakeThisOuTARRAKIS.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 .....haroldKILLspam@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 ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]

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 picnpokeKILLspamcdi.com.au

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}> 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 .....picnpokeKILLspam.....cdi.com.au

{Quote hidden}> 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. > > Mike Rigby-Jones > EraseMEmrjonesspam_OUTTakeThisOuTnortel.co.uk > > 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: > > > 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 picnpokespam_OUTcdi.com.au > >

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@rsmithKILLspambitworks.com 501.521.3908 Sr. Design Engineer http://www.bitworks.com

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}> 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 KILLspampicnpokeKILLspamcdi.com.au