More info needed on type of power supply or whether unit simply runs off 12 Vdc. A power converter will definitely do the trick, but obviously is not a solution unless it is already part of the EUT.
---------- >From: [email protected] >To: [email protected] >Subject: Low Frequency Conducted Immunity.... >Date: Mon, Oct 29, 2001, 10:42 AM > > > Hello Group, > > I am working with and electronic device which contains and audio output. > During a low frequency conducted immunity test, a tone can be heard at the > output of the audio section with a frequency equal to that of the test > frequency. The test starts at the lower end of the audio spectrum [~400Hz] > and progresses over time up to the top end of the audio spectrum [~30kHz]. > I would like to be able to filter the conducted noise from getting into my > electronic device. This is an automotive application, so if I am > unsuccessful alternator noise may also be heard in my audio signal during > normal operation in the vehicle. > > I have tried a few things to reduce the amount of noise such as: > > 1. LC filter with a cutoff at 1kHz > 2. Series inductance [large amounts ~ 3mH] > 3. Various common mode choke types, each with different core > materials [ie. iron core, ferrite core, etc....] > > #1 helped some, but is not effective enough, #2 was very successful, but > the size of the choke would be enormous and not practical in this > application, #3 was not effective > > > Can anyone suggest an improvement upon the three methods above, or suggest > something different? > > I would like to implement something on the board itself if possible, but > modification to the harness may be possible if necessary. > > > Thank you in advance for any help! > > > Regards, > > Scott Mee > EMC Engineer > > Johnson Controls Inc. > PH: 616.394.2565 > EMAIL: [email protected] > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
