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  1. #11
    Site Sponsor sande005's Avatar
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    Quote Originally Posted by gbkims View Post
    Fan variable speed? Wonder about the fan's speed electronics pulse width modulation causing some noise from on the 12V.

    My Bathroom Fan is on same fuse as the antenna booster, don't now if I have the problem or not.

    Could try the old standby: .001 microfarad disc capacitor across the +12V, -12V at the fan. https://www.amazon.com/Projects-B-00.../dp/B00E6PJ9ES
    Maybe a noise filter for 12V like https://www.amazon.com/PAC-CSS12-Pas.../dp/B000CEDZBA
    Yep, that (as well as possibly replacing the fan motor) would be the next suggestion, depending on how the testing turned out. But it looks like he found the easiest solution!
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  2. #12
    Site Sponsor gbkims's Avatar
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    Sounds like turning them off while watching TV is the easiest fix.
    Here's what 2 of the original fan motors I have at home look like. I'd replaced them with Maxxfans, nothing wrong with the OEM fans.
    They both generate some noise, one more than the other.
    These are the On/Off single speed fans.
    A .001uf capacitor had no effect on the noise measured.

    O'scope connected to a 12V battery at home, no motor running.
    I'm just measuring with AC coupling on the scope so don't see the 12VDC the noise (AC) is riding on.
    Click image for larger version. 

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    Motor1 On
    Click image for larger version. 

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    Motor2 On
    Click image for larger version. 

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    Last edited by gbkims; 01-09-2019 at 08:08 PM.
    - Gene

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  3. #13
    Long Hauler howson's Avatar
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    Quote Originally Posted by gbkims View Post
    Sounds like turning them off while watching TV is the easiest fix.
    Here's what 2 of the original fan motors I have at home look like. I'd replaced them with Maxxfans, nothing wrong with the OEM fans.
    They both generate some noise, one more than the other.
    These are the On/Off single speed fans.
    A .001uf capacitor had no effect on the noise measured.

    O'scope connected to a 12V battery at home, no motor running.
    I'm just measuring with AC coupling on the scope so don't see the 12VDC the noise (AC) is riding on.
    Jealous of your toy, Gene! I wonder if the MaxxFan generates the same level of noise. I'd speculate the answer is "no" so the OP may be able to fix his problem by replacing the fan.

    With that oscilloscope an adjustable filter circuit could determine the right capacitance needed to filter out the majority of the noise. That would be a fun experiment! Much easier than those dang-gum tapered vs straight thread plumbing dilemnas. (shudder)
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  4. #14
    Site Sponsor gbkims's Avatar
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    Quote Originally Posted by howson View Post
    Jealous of your toy, Gene! I wonder if the MaxxFan generates the same level of noise...Much easier than those dang-gum tapered vs straight thread plumbing dilemnas. (shudder)
    Hi Howard,
    It has me curious about the Maxxfan, next time I'm at RV storage I'll look at them with the scope on the fuse they run on.
    I did try over coffee this morning a different value and combo of .1uf caps across the motor leads & motor lead to case per another site, no effect on the noise.

    Checked one of my 12V computer brushless fans, like the ones on the RV frigs.
    Click image for larger version. 

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    Same at 10mV/Division Scale
    Click image for larger version. 

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    Last edited by gbkims; 01-10-2019 at 06:18 AM.
    - Gene

    Kim & Gene
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  5. #15
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    You guys are hurting my brain, I will stick to plumbing.

    Brian

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