Bike lights and RFI suppression

poguy · Oct 19, 2013

I have one of the cheap XM-L LED lights on the bike. It works OK but on 'low' there is enough RFI to keep my wireless cyclocomputer from working.

Unfortunately there isn't enough room inside for a few extra capacitors.

Have any of you experienced or fixed something like this? The next option is to cut the cord and add a low-pass filter between the light and the battery.

And I don't have a spectrum analyzer, so it is a matter of trying something to see how it works.

PapaLumen · Oct 19, 2013

My old magicshines used to interfere with my wireless computer. Didn't manage to fix it but I use my phone nowdays. Interested to see if you fix it.

yellow · Oct 23, 2013

does an aluminium housing "shield" (?) the frequencies?

So possibly changing the sides of light and Computer could help?
(hole where the cable gets out of the housing on the other side)

or moving them as far as possible to the sides of the handlebars?

last ditch: put protective layer (spray paint + let dry) over the electronics and then apply a layer of alum. foil?

:thinking:

Hashime · Oct 25, 2013

If you have a ferrite ring kicking around try wrapping the cable from the battery pack around it. You might be able to shift the frequency enough to solve the problem if the magnetic field is coming from that area.

poguy · Nov 20, 2015

Tried a ferrite bead, didn't work. RF probably getting out through power cord.

I have some DC coax connectors on order. Next step is making an inline filter with a male connector on one end and a female on the other.

NoNotAgain · Nov 22, 2015

poguy said:
I have one of the cheap XM-L LED lights on the bike. It works OK but on 'low' there is enough RFI to keep my wireless cyclocomputer from working.

Unfortunately there isn't enough room inside for a few extra capacitors.

Have any of you experienced or fixed something like this? The next option is to cut the cord and add a low-pass filter between the light and the battery.

And I don't have a spectrum analyzer, so it is a matter of trying something to see how it works.

How about taking a piece of engine braided ground strap and feeding your power cable through it? http://www.mcmaster.com/#grounding-straps/=zxb6y6

poguy · Nov 24, 2015

Found a spot for a tantalum cap and it helped a bit. Tantalum's aren't the best for higher frequencies. Next will be a ceramic chip cap. Perhaps also on output to the LED's.

Bike lights and RFI suppression

poguy

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PapaLumen

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yellow

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Hashime

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poguy

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NoNotAgain

Flashlight Enthusiast

poguy

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