Waffle

Member
Oct 19, 2004
37
0
Yes, I know, this topic has been beaten to death. Do a search, brake AND light, brake AND switch... Did that. Lot's of threads, problem was half the posts were missing - made it a little hard to follow...

I'm hoping that somebody who has successfully rigged a brake light on their KDX will take pity on me (and I'm sure there will be others to follow) and describe exactly how they did it.

I would like to work with what I have on the bike (and ordered) keeping things as simple and clean as possible. I have a 'single filament' LED bulb in the stock housing - I know LED's don't have filaments, that's why I use it - too much vibration for a regular bulb. I ordered a hydraulic pressure switch for the rear because I damaged my rear brake line (got a bunch of old wire fencing tangled up in the rear wheel) and need to replace it anyway. I read the post about putting a resistor in the line to dim the taillight, then bypass the resistor with the brake switch to make the bulb brighter when the brakes are applied. I went to my local Radio Shack to pick up the 5 ohm resistor but could only find 1 ohm and 10 ohm. So I checked Radio Shack online and found that is all they have. Apparently they don't make a 5 ohm resistor anymore. Also, the resistors come in two varieties, ceramic heavy-duty looking ones and a tiny glass jobbies that you would find on a circuit board. Which ones do I want? At first I thought I would need the ceramic ones, but thinking some more on it I'm afraid it might be for 120 volt AC. The clerk was no help at all, he's a polite kid, but no more knowledgable on electrics than I am.

I was also thinking that perhaps I don't need a resistor. What if I spliced a wire off the line to the taillight through the brake switch effectively running two lines in parallel when the brakes are applied. I my rather feeble mind this would increase the brightness of the taillight due to the extra juice, yes? Seems to simple, there must be a flaw.

OK, let the abuse begin.
 

Colorado Mike

Member
Jun 28, 2004
97
0
extra juice from 2 parallel wires ? My God man!! you've stumbled upon the solution to the world's energy shortage!!! get crackin on the cure for cancer now.! Sorry man, no. but you're kinda close when you say parallel, but for a different thing. If you need a 5 ohm resistor, but only can get 10s, take two 10s (get the big ones) and put them in parallel. you'll effectively have a 5. Electronics is funny that way. I was planning to do the same thing you are, but I was going to get a dual LED tail light assembly. let us know how it works out.

Mike.
 

canyncarvr

~SPONSOR~
Oct 14, 1999
4,005
0
Ha! 'My God man!!' That was a good one! ;)

Yes on the parallel 10ohmers (if you want 5 ohms) and yes on the ceramic ones. You do get 'parallel' meaning to place them side by side (not end to end), connect the adjacent leads of each of the two resistors to the wire (that goes wherever)?

There is going to be a problem, though.

A filament will light differently (change in lumen output...brighter/dimmer) with two different voltages. That is true of either an AC (alternating current) or DC (direct current) application.

But...your bike is not DC. It's AC. Take your voltmeter set to DC and measure the output of your lighting system somewheres. You won't get much (if you get anything at all).

The LED 'light' you plugged in has a rectification circuit in it that...well..does exactly that. It rectifies the AC of your bike to the DC required to run the LEDs. It's not going to act like a brake light with the resistor/dual-lead/bypass idea as a filament type bulb would. I'm not saying you absolutely will not be able to tell any difference...but it won't be much between brake and tail.
 

KTM Mike

~SPONSOR~
Mi. Trail Riders
Apr 9, 2001
2,086
0
Seems to me the easiest way would be to simply wire up a dual filiment socket and stick in a dual filament LED bulb? I just bought 2 of those bulbs for like $5 each (I bought one spare just in case). quick and easy ...plug and play (at least on my KTM as it is already set up with a dual filiment socket).
 

Waffle

Member
Oct 19, 2004
37
0
Yeah, I'm going to ditch the resistor set-up. I only went in that direction because what I had on the bike was the single filament LED and I had to hunt high and low to find one (every auto parts, truck dealer, motorcycle shop, Walmart, etc within a 20 mile radius) nobody had LED's! Had to get them off eb@y. But today at my local auto parts store, I found that they are finally stocking the dual filament LED's. So I picked one up and a socket to fit and will install as soon as the weather gets a little friendlier (unheated shed & winter has returned to NH).
 
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