Wireless interferrance

[danTHEman]

Hi everyone,

Have spent quite some time looking at these forums and the have been very helpfull indeed.

From what I have read I have bought two XR-E R2 dropins. The first test was with excelent results, apart from, when the lights are on my cateye wireless speedo stops working???:shrug:

As this was my first attempt at an LED light I wasn't running them in any sort of casing.

Has anyone else experienced this or will having them in an aluminium casing help.

Many thanks,
Dan.

 

[Resqueline]

Switchmode drivers will radiate some RF energy that can interfere with other gadgets, unless they are sufficiently shielded. Chances are your speedo will work with the light installed in an aluminum case. The case will short out all electric fields, and most of the magnetic fields, exept maybe out front.
Any data on what frequency the speedo uses btw.?

 

[Steve K]

do you have any pictures of your lights/bike/computer? Does the light have an internal battery (like a m*glight), or is there an external battery pack?

If you are using an external battery pack, there may be ways to modify the circuit or wiring to reduce the emissions.

With an internal battery.... the options are fewer. The best option might be simply to move the light and computer as far apart as possible.

I do this sort of work for a living, and it's rarely simple or easy to fix. (unless the designer was really clueless)

best wishes,
Steve K.

 

[Eamon]

Just FYI,
My Minewt X2 prevents a Cateye wireless from working, but only when in flash-mode. The housing is cast aluminum and all the driver electronics are inside it. Apparently I am not the only person to have this problem.
Cateye has changed the transmission freq of their wireless computers, and now say that the problem is solved. I've not had a chance to test this yet.

Eamon

 

[danTHEman]

Wow, didn't expect such a response from my first post. THANK YOU.

As this is my first attempt at moding lights etc, all I have done is attach one DX sku.14442 to an old reflector mount wired to two 18650's.

This was just a test to see what sort of output/runtime I would get. Will check computer transmition freq and find a suitable casing and try agian.

Is it possible to mount the driver board with the batteries or will the wire lenght affect the current to the LED?

Many thanks again for all your advice it has been very helpfull, I have to say I think I've got that moding bug so this will probably be the first of many posts

 

[Eamon]

When I talked to Light&Motion a while ago, they said that the only way to keep the ARC from killing a wireless connection was to build a Faraday cage around the entire light head. They were not feeling compelled to do this.
For LED setups, Resqueline's comment about switchmode drivers would explain observed phenomena.
Do please post results, I doubt I'm the only curious one. And the ability to run wireless computers would be nice.

Eamon

 

[Steve K]

Wow, didn't expect such a response from my first post. THANK YOU.

As this is my first attempt at moding lights etc, all I have done is attach one DX sku.14442 to an old reflector mount wired to two 18650's.

My only suggestion right now would be to try to add some capacitance at the circuit board where the battery contacts are located. Specifically, try a 0.01uF ceramic cap from the positive to the negative battery contact. Maybe even add a 1uF ceramic cap in parallel with that. This will at least prevent the switching power supply from drawing large, fast current spikes from the battery. The caps will provide much of the current spike, reducing the high frequency transients in the long wires (relatively speaking) going to the battery.

A faraday cage is always an option, but it's usually tougher to implement.

Steve K.

 

[unterhausen]

seems like I saw somewhere that cateye modified their wireless to fix this. I'm really surprised that it would cause a problem.

 

[PCC]

Just FYI,
My Minewt X2 prevents a Cateye wireless from working, but only when in flash-mode. The housing is cast aluminum and all the driver electronics are inside it.

Eamon

The majority of the electronics are in the battery pack of the Minewt headlamps. I bought the Mini-USB and the only electronics in the head is the emitter. Granted, this is the cheaper model but I bought a replacement head from a pre-X2 Minewt for the aluminum housing and it only has a few resistors and those tiny LED emitters in there along with the Luxeon emitter.

 

[danTHEman]

A lot of helpfull infomation, thank you.

I am talking to a friend of mine about making a housing and will keep things up dated.

Specifically, try a 0.01uF ceramic cap from the positive to the negative battery contact.

Steve K.

As for capacitors and such like, its all a bit over my head :thinking:. Thank you for the advice though. would you be able to go into a bit more detail please.

Thanks.

 

[Steve K]

As for capacitors and such like, its all a bit over my head :thinking:. Thank you for the advice though. would you be able to go into a bit more detail please.

The capacitor, located at the power input of the driver board, will provide those noisy little bursts of current that create a lot of electrical noise.

Ceramic caps are the most common type in this size. You can check with your local 'tronics supplier. Just get a cap rated for 10v or 16v or whatever the battery voltage is (and add 30% or so as a safety margin).

Manufacturers can provide a lot of info on the caps themselves and how to use them. One of these is Kemet, with info at www.kemet.com

the various catalogs of their product types, as well as technical literature, is here:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/products

A little surface mount chip capacitor might be the best for this job. Maybe an 0805 size cap, with a X7R rating? If we had pics of the circuit board, we'd be able to make more reliable suggestions.

good luck,
Steve K.

 

[danTHEman]

Sorry I haven't replied, I've been away at work with limitted access to a computer.

Thanks to all your suggestions the issue is now solved. I have installed the drop-in in a maglite head and all interferrance has gone.

Thanks again for all your help, if I ever sort out my camera I'll post some pics of my final build.

Regards Dan.