Headlight Modulator Noise - redux

Discussion in 'The Projects Forum' started by dlpweb3, Jan 10, 2012.

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  1. dlpweb3

    Thread Starter New Member

    Jan 5, 2012
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    A year ago SgtWookie & JFairman had an interesting thread about a choke design to filter out noise generated by a headlight modulator (240Hz switching of a 12V, 100W load). SW came up with a toroid recommendation using something from Goldmine - but that toroid is no longer available and had pretty unusual characteristics (Al of 9,900).

    Is anyone familiar with an analysis of this type who can help suggest another toroid that will work in the circuit? Here is a link to the original discussion:

    http://forum.allaboutcircuits.com/showthread.php?t=40157&page=4
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Try digikey, mouser, etc. for the cores. As long as you end up with 13mH each using 18ga magnet wire.



    We can't really change the circuit or offer new designs due to changes in the TOS.

    This Toroid has an Al of 10,000, so should work fine. T-38 series, a little over an inch in outside diameter, enough room to get the windings on. For the filter, a little extra inductance will help.

    Stack the two cores as shown in This schematic Should eliminate 60%+ of the noise.
     
  3. Georacer

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    Nov 25, 2009
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  4. dlpweb3

    Thread Starter New Member

    Jan 5, 2012
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    THANKS, ThatOne!

    Had the circuit you referenced - that was what I was attempting to duplicate. In such a choke (say, for some theoretical non-automotive application such as dampening noise in a machine room) .... would the values of the selected capacitors change with that change in Al?

    Have been trying to figure this out ... came upon the little freeware "mini Ring Core Calculator", but have not yet been able to guess what the various values are. For example - the core you suggested is "T38", and I don't see that listed. Another - how does this little pgm. handle a 2-core stack?

    Thanks again. Greatly appreciate your time and knowledge (and willingness!).
     
  5. Georacer

    Moderator

    Nov 25, 2009
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    Your questions on this topic cannot be answered. Please respect the rules of the forum.

    Feel free to browse the site, but you need to look elsewhere for information on this project.
     
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