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Also, does anyone have a fix for this. I saw that wiring a resistor between the 2 signal wires is the typical fix, but at what ohm? One site claims that you can use four, 6 Ohm resistors (1 at each light) or two, 3 Ohm restitors (1 left, 1 right)...not being an electrical engineer and it being about 10yrs since I last had physics, could someone help me out?

Thanks,

Eric

Using the theory that the you've provided, you've just proven that each light in the left and right circuits are the same place electrically speaking, so I wouldn't bother adding resistors at the front and back. Just do it in the rear where it's easy to get to.

--Fillmore

I am not a real Sparky, but you are right, resistance goes up as temperature goes up.I'm not an EE, but I'm pretty sure that the resistance of a light bulb changes a lot due to the extreme temperature change of the filament. Perhaps someone more sparky will weigh in...

http://www.superbrightleds.com/1157.htm

See the paragraph:

I think what they mean by a load resistor across the terminals is a parallel connection.

You use the reciprocal rule if they are in parallel, but the sum of the resistance if they are in series.

If the signals are in series, you could just use something like a 12 ohm resistor on just one signal. If they are in parallel, then you're right and you'd drop down to a 3 ohm.

--Fillmore

SO, the point is that when you engage either left or right, there is current flowing through BOTH sets of indicators. But, only the chosen side gets enough draw to light up the bulbs.

Chris

Assuming parallel front and back 6ohm original bulbs, the equivalent circuit is like this;

Then, when you had just the leds front and rear, it is like this, and is equivalent to a blown bulb;

Adding a 3ohm resister in parallel to the front and rear bulbs should give an equivalent resistance similar to the original (assuming the original had 6 ohm bulbs);

mitt

I assumed the bulbs were parallel, so that if one burned out, the other would still work.

sandin

Looks like I'm off to Radio Shack (or is it Shaq?) this afternoon.

Thanks again for all your help...I'll post w/ the final outcome whence complete.

Eric

So what are you suggesting? 4A will burn something up? I thought that was what fuses were for. What size resistor do you suggest?12V / 3Ohms = 4A

P = V*A = 48W

That's one big a$s resistor burned out spot.

What is the resistance of the orignal bulbs? That was something I still don't know. I was just doing the math to show how to make a circuit equivalent to what was there originally. I have not seen anyone else post something that might help Eric fix this problem yet. [smiley=idea.gif]

mitt

P=power (watts), I=current (Amps), E or V = Volts

P=I*V

I = P/V

R=resistance in ohms.

Now, use P=I*I * R to find "resistance"... (Note that I*I is I squared)

R = P / I*I

But, yes, a 48W 3Ohm "resistor" would more commonly called a resistive load, as it would be bigger than a Coke can. Most of the resistors you see used in electrical devces and on circuit boards are 1/4 Watt. We tested them and they'll turn black between 1/2 and 1/3 W and if done right, will actually explode and leave burn marks if you quickly approach 1W. This is called "letting the smoke out". Black devices with multiple pins on them hold a LOT of smoke. ;D

The gizmos you see for sale are likely a wound coil of some sort, properly called an inductor. The more common name is "ballast", which implies resistor or load.

Chris

If this 50watt 6 ohm resistor is as big as a coke can, those must be some 1 inch diameter cables running out of it.

And I think that bulbs have resistance, otherwise they would draw infinite amps. They have a tungsten wire that has a high resistance per unit length property that causes them to heat up (ohmic heating i^2*R) and emite light. They are less efficient than LEDS because the majority of energy is wasted as heat.

I still have yet to see a definite answer for Eric from anyone on how to fix this problem.

mitt

: Well, obviously, if that's purely a resistor, it's something new-ish. Certainly isn't 100% ceramic, huh? And keep in mind that this thing is like a 50W bulb. (well, 60W since you don't see 50W ones...) and will get equally warm. BUT, since sarcasm is directed at me indicating that my presence is unwanted, I'll bow out of this thread.If this 50watt 6 ohm resistor is as big as a coke can, those must be some 1 inch diameter cables running out of it.

Chris,But, yes, a 48W 3Ohm "resistor" would more commonly called a resistive load, as it would be bigger than a Coke can.

Chris

I was just giving back some of the sarcasm you started with

I am not an expert on resistive materials, or how this 50W device is constructed, but I do know that everything has a resistance. Even wire is a resistor (just a really slight one). I deal with it daily in the form of silver, copper, and tungsten contacts in the electrical industry. And our contacts can handle 100KA at 600V, so we are talking MW of power.

I am just trying to keep this topic simple, talking about resistors as generalities, what you can buy at a Radio shack or an auto store.

No offense intended. I think it was a good discussion, and hopefully we can see the results when finished.

mitt

P

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Here is a link to a similar resistor spec sheet.

http://www.heiresistors.com/aluminum.htm

Digi-Key Part Number TMC50-6.0-ND Price Break

5.21

Here is the part number and price from digikey. They are a component catalog with more spark chaser parts than you can throw a stick at.

Manufacturer Part Number TMC-50-6.0-1%

Description RES ALUM HOUSED 6.0 OHM 50W 1%

Quantity Available 489

This (and the kits others found) will work if you install across the + and - leads.

Multimeter tip for hinkle_e the scales you are looking at are multipliers. Is you have the mater switch in the 1 OHM range setting then you need to use the "standard" scale. The 200 scale corresponds to a different switch setting labeled as such. If you are new to spark chasing I would but a decent digital meter, they are much easier to use and remove some of the confusion the bk precision from digikey are good, and radio shaK versions are OK too, should run about $30-$50. Hope this helps I chased sparks for a long time to earn a living.

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