# [EVDL] HID Headlight Transformer Interference



## EVDL List (Jul 27, 2007)

Hello EvListers,
First off Happy 4th of July !
My problem today, actually for over a year, I just didn't know it, is this dc-dc converter(transformer) for my HID headlights.

http://www.flickr.com/photos/[email protected]/3688081608/
http://www.flickr.com/photos/[email protected]/3688081342/

After nearly two years of driving my 928 Porsche conversion I finally put a radio in it. Only to find I have a lot of radio electrical noise, but not from the usual suspects,controller,brushed motor.
Here is what I have tried so far to minimize the interference.
Tried capacitors on the 12v input (220uf & 2200uf), lights wouldn't come on !
Diode to ground on the input side
ran the 12v source through a relay directly from my 12v battery
put the unit in a aluminum sealed box (trying to eliminate conductive inter.)
None of these made a difference.
I also wanted to know if the noise was inductive or conductive, so I powered the transformer from a separate 12v battery (all interference went away, so its Inductive, right ? )
Now I admit I'm an electronic hack, so please be gentle and not to technical with your advise. 

Thank you all in advance !
Jeff



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## EVDL List (Jul 27, 2007)

On Sat, Jul 4, 2009 at 3:39 PM, Jeff Mccabe<[email protected]> wrot=
e:
>
> Hello EvListers,
> First off Happy 4th of July !
> My problem today, actually for over a year, I just didn't know it, is =
this dc-dc converter(transformer) for my HID headlights.
>
> http://www.flickr.com/photos/[email protected]/3688081608/
> http://www.flickr.com/photos/[email protected]/3688081342/
>
> After nearly two years of driving my 928 Porsche conversion I finally =
put a radio in it. Only to find I have a lot of radio electrical noise, but=
not from the usual suspects,controller,brushed motor.
> Here is what I have tried so far to minimize the interference.
> Tried capacitors on the 12v input (220uf & 2200uf), lights wouldn't come =
on !

Adding capacitors in parallel to the input side of the dc/dc should
have at worst done nothing, not stopped the lights from turning on.

Also I would have started with a smaller value. Larger caps are for
dealing with lower frequency fluctuations (more often sudden spikes in
power use). Small caps will pass RF.

> Diode to ground on the input side

This was not likely to do anything.

> ran the 12v source through a relay directly from my 12v battery
> put the unit in a aluminum sealed box (trying to eliminate conductive int=
er.)
> None of these made a difference.

So the noise isn't traveling threw the air but back up stream from the
HID DC/DC to the +12V source and then to everywhere else.

> I also wanted to know if the noise was inductive or conductive, so I p=
owered the transformer from a separate 12v battery (all interference went a=
way, so its Inductive, right ? )

You got good data from your experiments but not the right conclusion.
Your last experiment isolated the two things and stopped the problem,
so it is conductive. I think you might try an inductor in series with
the lamps to block the noise from propagating. How far (physically) is
the DC/DC from the Lamps? You want them and anything blocking the
noise to be close in proximity to minimize any RF prorogation (Not
that you seem to have evidence of any).

> Now I admit I'm an electronic hack, so please be gentle and not to tec=
hnical with your advise.

The capacitors were a good guess.

> Thank you all in advance !
> Jeff

Evan


-- =

http://www.coe.neu.edu/~efoss/
http://evanfoss.googlepages.com/

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## EVDL List (Jul 27, 2007)

> Jeff Mccabe wrote:
> 
> > My problem today, actually for over a year, I just didn't
> > know it, is this dc-dc converter(transformer) for my HID headlights.
> ...


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## EVDL List (Jul 27, 2007)

Happy 4th Roger,


Sent from my iPod



> Roger Stockton <[email protected]> wrote:
> 
> Jeff Mccabe wrote:
> 
> ...


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## EVDL List (Jul 27, 2007)

Evan,
Thanks , your advice agreed with Rogers.
I have several things to try tomarrow.
Happy 4th,
Jeff

Sent from my iPod



> evan foss <[email protected]> wrote:
> 
> On Sat, Jul 4, 2009 at 3:39 PM, Jeff Mccabe<[email protected]> wrote:
> 
> ...


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## EVDL List (Jul 27, 2007)

Roger,
I tried what you suggested with using capacitors between 12v & ground. First with just a .1uf, no improvement. Then added a 1uf, about 30-40% reduction in line noise. Then added a third one in parallel of 2200uf. This has reduced the niose 90 plus %
Im still waiting on the 12v inline filter. When it comes, I'll probably use this between the radio and its 12v source to get rid of the remaining noise sources .
Thanks again for your help , 

Jeff

Sent from my iPod



> Jeff McCabe <[email protected]> wrote:
> 
> Happy 4th Roger,
> 
> ...


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