Electritions: Resistor question

[big0mike]

So I got a bike this weekend. A 2004 Honda CBR1000RR. (http://perfectmancave.com/forum/showthread.php?t=5819) The only problem with it is the aftermarket brake light & turn signals. The left turn signal does not work. The seller explained to me the problem so I took the seat off and found the loose wire. What it is is apparently the two turn signals both going into separate 20 watt 5 ohm resistors. The wire on one is broken off so it can't be repaired but me and a buddy bypassed it completely and everything still works fine so I'm not sure what the hell that resister is doing and if it's even necessary. The seller said it "slows down" the LED turn signals but that doesn't make any sense to me.

Anyone know what this resistor is doing? Is it necessary? Does it specifically have to be a 25w 5o resistor?

I've got a line on getting another but before I go to the hassle I wanna know if it's needed.

Thanks,

[Quads]

Picture, rough schematic, and the colors bands on the resistor?

[Happy Hazard]

Well, the purpose of the resistor is to A resistor is a two-terminal electronic component designed to oppose an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law: V = IR. The electrical resistance R is equal to the voltage drop V across the resistor divided by the current I through the resistor. Resistors are used as part of electrical networks and electronic circuits.

http://en.wikipedia.org/wiki/Resistor

So in essence, the resistor is dropping the voltage output to the turn signal. The most that will probably happen is that you will burn the light out faster, since the voltage going to it is not being mediated by the resistor. Im sure it isnt a fire hazard, since the voltage is so low at that point, but i would recommend getting a resistor with the same color bands and soldering it inline before the light in the same place where the previous one was.

[mikeyinsd]

When I switched to LED tail lights in my jeep before I added the resistor the turn signals would blink really fast... after the installation of the resistor, they blinked normally. The resistance draw from the LED's was less than the regular bulb type thus making the blinking solenoid go crazy thus the need for the resistor. ;)

[big0mike]

Excellent. Thanks. The resistor is one of those funny looking ones: Looks like a piece of mortar encased in plastic on all but one side. The one's at Radio Shack had a long piece of wire you solder to coming out of both ends and one was broken off EXACTLY at the point it enters the plastic housing so there's no repairing it. I'll get one on the way home.

[big0mike]

Follow up question: The resistors currently in place are sandstone resistors 20 watt 5 ohm. I called a place in town that carries a lot of this specialty stuff and they have 25 watt 4.7 ohm and 25 watt 5.1 ohm. Will either of those work for my application? I'm told by the original owner that their purpose is to slow the signal down, presumably so they don't blind rapid fire so I'm thinking either one of those resistors will work fine. Any idea?

[Doctor_XXX]

Follow up question: The resistors currently in place are sandstone resistors 20 watt 5 ohm. I called a place in town that carries a lot of this specialty stuff and they have 25 watt 4.7 ohm and 25 watt 5.1 ohm. Will either of those work for my application? I'm told by the original owner that their purpose is to slow the signal down, presumably so they don't blind rapid fire so I'm thinking either one of those resistors will work fine. Any idea?
Grab one of each? What are they, like a nickel a piece? Try the 5.1 ohm one first, and if it works, leave it in there. If (for some crazy reason) the extra 0.1 ohm is too much and the signal doesn't work, swap it out for the 4.7 ohm version. My guess is the 5.1 ohm one would be "close enough".

[big0mike]

The problem is that it appears to work without them... I'll get the 5.1 and that should work. If it does what I'm thinking it does it'll just make them blink slower by exactly .1... whatever that is :)

[Quads]

I don't think you're looking at a resistor.
Please take a pick and post.

[bigslickwood]

Sounds like if it's a 25w that it's in there for power dissipation. The LED doesn't need near the juice that an incandescent bulb would. The resistor steps down the voltage and burns off power in the form of heat (may also affect timing as mikey said, but that's probably a function of limiting juice into a capacitor). It may work for a while without it, but could greatly reduce the life of the LED system. 5.1 or 4.7 shouldn't make a difference.

[big0mike]

http://www.wideopenphotography.com/photos/resistor01.jpg

I'll plan on getting the 5.1 ohm version...