LED on the spark plug wire?

I would like to attach a string of LED's to run off of the spark plug wires on a motorcycle but I don't know where to start, but it would look awesome flashing under the tank at night, any takers?

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wgreen22 years ago

Use a coil of wire. Use solid wire, not stranded wire. Place a thin plastic tube around the plug wire, you may need to split the tube and tape it back together as the tube should be only slighty bigger than the plug wire. Wrap a long peice bell wire or telephone around the tube. Use at first only a few wraps(turns) of wire with long leads. Connect a meter to the leads to check voltage and polarity. If the meter indicates negative polarity or the needle drops below zero, reverse the leads. If the voltage is above 1.5 vdc unwrap some of the turns around the tube. If the voltage is less than 1.5v add more wraps or turns around the coil. Attach the LED once 1.5v is acheived, shorten the wire leading from the coil you wrapped around the plug wire as needed.

and7barton8 years ago
Use a Neon ! - I used one on my Gas Turbine engine - simply cut the spark-plug cable and inset the neon in-line.
NachoMahma8 years ago
. Neon bulbs (or tubes) might be a better choice. As CameronSS points out, LEDs are very low voltage devices and will probably fry without some sort of interposing trigger circuit.
lemonie8 years ago
Wire them into the 6 / 12V supply, but take a trigger from your ignition circuit. I guess you've got some kind of Magneto - you might be able to add an additional small coil that will trip a transistor circuit.

CameronSS8 years ago
That does sound like it would be cool. However, keep in mind that LEDs usually run off of 1.5V-3.5V, whereas spark plugs can use anywhere from 40,000V to 100,000V. If you want to run it off the spark plug wires, you will probably be better off with neon or fluorescent lamps.

Actually, you could possibly even run them wirelessly: if the electromagnetic field around the wire is strong enough, simply placing a neon lamp or fluorescent tube next to it will make it light up. If you don't have one handy in your junk pile, you can pick a small neon lamp up cheap, which you can simply hold up next to the spark plug wires with the engine running to test the concept. I'd try it for you, but I don't have any engines around here with exposed plug leads.