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N1DeltaWhiskey(at)comcast
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 Posted: Thu Aug 02, 2007 9:02 pm Post subject: Noise filter |
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Bob, et al,
A cohort is having problems with a Century autopilot induced audio noise
into his headphones. From any testing we have done, this appears to be
motor noise (based on spool-up/spool-down noise) transmitted into the power
lines. The Century information indicates that it can produce noise in some
avionics at the 5 kHz level. If it is not power line noise, then it might
be EMF radiation being picked up by the radio or phone circuits.
I have found some information regardng design of a "twin-T band-stop" filter
that could probably be used to filter the offending frequency out of the
offenders power line.
Assume others have probably had this type of problem an wondering how it was
solved.
On the dumb question front, the above circuit references a source and load.
I would normally think of the power supply as the source and the autopilot
the load. But, given the noise is from the autopilot, would it not be the
source and the rest of the circuit the load?
Any insight appreciated.
Doug Windhorn
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rjquillin
Joined: 13 May 2007
Posts: 123
Location: KSEE
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| Posted: Fri Aug 03, 2007 12:13 am Post subject: Noise filter |
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At 22:00 8/2/2007, you wrote:
| Quote: | A cohort is having problems with a Century autopilot induced audio
noise into his headphones.
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What model CFS system is it?
Ron Q.
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bobf(at)feldtman.com
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| Posted: Fri Aug 03, 2007 2:40 am Post subject: Noise filter |
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You might try wrappig about eight wraps of the power, and control cables through a ferrite bead (palomar engineers)- I assume you are using twisted pair or coax shielded wire?
bobf
W5RF
On 8/3/07, Doug Windhorn <N1DeltaWhiskey(at)comcast.net (N1DeltaWhiskey(at)comcast.net)> wrote:[quote] --> AeroElectric-List message posted by: "Doug Windhorn" <N1DeltaWhiskey(at)comcast.net (N1DeltaWhiskey(at)comcast.net)>
Bob, et al,
A cohort is having problems with a Century autopilot induced audio noise
into his headphones. From any testing we have done, this appears to be
motor noise (based on spool-up/spool-down noise) transmitted into the power
lines. The Century information indicates that it can produce noise in some
avionics at the 5 kHz level. If it is not power line noise, then it might
be EMF radiation being picked up by the radio or phone circuits.
I have found some information regardng design of a "twin-T band-stop" filter
that could probably be used to filter the offending frequency out of the
offenders power line.
Assume others have probably had this type of problem an wondering how it was
solved.
On the dumb question front, the above circuit references a source and load.
I would normally think of the power supply as the source and the autopilot
the load. But, given the noise is from the autopilot, would it not be the
source and the rest of the circuit the load?
Any insight appreciated. [quote][b]
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N1DeltaWhiskey(at)comcast
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| Posted: Fri Aug 03, 2007 11:05 pm Post subject: Noise filter |
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Century 1. Apparently an early model.
Doug
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N1DeltaWhiskey(at)comcast
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| Posted: Fri Aug 03, 2007 11:07 pm Post subject: Noise filter |
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Negative. Sounds like you are suggesting twisted B+ and B- wires might correct the problem. Correct?
Doug
[quote] ---
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