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-   -   Electrical wiring techniques (https://www.bikeforums.net/electronics-lighting-gadgets/851160-electrical-wiring-techniques.html)

Pinkelephant64 10-08-12 09:53 AM

Electrical wiring techniques
 
Is there a thread or sticky showing off the wiring skills of the members?


I am probably getting the shimano dynamo hub with the following:

the "Axa Nano 50 Plus" has a USB port for charging toys
http://www.velofred.com/product_info...roducts_id=891

and the "Busch & Müller Toplight Line Brake Plus" has a break light when it detects the dynamo slowing speed
http://www.youtube.com/watch?v=KzQoUy3wHd0
I was considering getting some FM coax from a ham radio shop that is around the same size as a brake cable. That way I can use cable hanging hardware to run it from the headlight to the tail light. I can ground the coax's outer shield and that should greatly reduce the RF put out by the dynamo. The positive would be in the shielded core and the ground would be the frame and the outer shield.
I'm building a show-off toy with custom decals. I want clean wiring and no drilling into the frame.

dougmc 10-08-12 10:38 AM


Originally Posted by Pinkelephant64 (Post 14818435)
I can ground the coax's outer shield and that should greatly reduce the RF put out by the dynamo.

The dynamo doesn't put out any significant amount of RF. The small signal it does generates is well within the audio range (as opposed to the radio range) and would not be radiated efficiently as RF without a many mile long antenna.

The LED light could emit some RF, however. If that's a problem, I'd suggest wrapping the power cable around some ferrite beads right near the light.

And note that you gain nothing by "grounding" the coax to the bike frame, as the frame is not connected to the ground (you see, there's these big round rubber insulators between the frame and the ground.) In the case of a car, the "ground" is simply a return path for the electricity -- the frame is used as part of the circuit. You could do that on a bicycle too, but it probably makes more sense to just use two wires.

Using coax because it's the right size and shape makes sense, but coax is a lot more fancy than you need for this low frequency AC signal. You don't need the shielding and don't need the stranding to overcome the skin effect, for example. If you could find DC wiring (it's not DC, but the frequency is low enough that it doesn't matter) that fits the shape and color you're looking for, that would work just as well.

Pinkelephant64 10-08-12 10:52 AM

I want a wireless cateye cadence computer but while shopping for dynamos, I see many people complaining about interference from the dynamo messing up the wireless signal. I planned on "grounding" to the front and rear rack mounting screws. I assume the connection would pass thru the fork bearings. but, the grounding would be redundant and would probably increase the RF.

I intended to use ferrite beads at the dynamo but maybe I should use them at the lights also (as long as I can hide them)

dougmc 10-08-12 12:07 PM


Originally Posted by Pinkelephant64 (Post 14818630)
the grounding would be redundant and would probably increase the RF.

I don't think it would have any effect at all.


I intended to use ferrite beads at the dynamo but maybe I should use them at the lights also (as long as I can hide them)
The dynamo doesn't need them -- only the light would, and even that's a maybe.

ctpres 10-08-12 02:04 PM

Be prepared to experiment with the ground at both ends. You might have fewer noise problems with only one end grounded.


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