new and need help!

[Robi D]

hi all, first time poster and need some help. i am very new to all this and am hoping that i can get some help. i restore classic italian scooters, vespas and lambrettas. i am currently restoring a 1959 lambretta li 150. i have upgraded the electrical system to the best system available at this time. it is called a variotronic kit. it boasts 12v and 90w output. these are two stroke scooters and this system provides a dual spark that burns off excessive unspent gas and oil so effectively that the scooter could pass emissions tests in the state of california! so i have purchased a new halogen bulb for the headlight and am working on an LED tail light. i found some pics of a setup someone had made on one of my scooterclub websites, but no one knows anything about it! who made it etc. so i will try to include the image at the end of this post. i have spent the afdternoon trying to get familiar with LEDs and their parts etc. i have to admit i am very interested. although a little slow!!! i think i have a pretty good idea of what LEDs i need, 5mm, but am unsure of what mcd i need them, and then what size resistors. though i think 1/4w would be fine for each series. please take a look at the diagrams and see if they make any sense to you and if i left any info out just ask me. oh and i just thought this is a 12vdc system that runs off a stator plate (magneto).

 

[LukeA]

The mcd rating of 5mm LEDs for this purpose is not too important.

Depending on the Vf of the LEDs, I'd think about running 4 in a series and running 3 parallel series in this setup.

If you wanted, you could put in an LED headlight.

 

[Robi D]

really a headlight bulb too? how hard would that be?
thanks

 

[LukeA]

really a headlight bulb too? how hard would that be?
thanks

It's pretty simple really. I built one for a car. For this scooter, I would scale it down to 3 or 4 dropins (this is a guess, if you know the wattage or lumen rating of the halogen, the number of dropins can be tailored to match that). You can use airflow to help with cooling. DX carries the optics that I used now (I would diffuse at least two of them), but you could experiment with other optics if you feel adventurous.

I based the idea off of sku.6090 because they can take and regulate automotive voltage. I didn't use the reflectors that come on the dropins because they didn't control the light as well as the optics can.

 

[Robi D]

wow! that is awesome. i think i better work on my tail light set up first. that looks a little bit more complex. also i'd have to make it work in the bulb holder it has so that it would still have the reflector. right? let me think about this one!
thanks

 

[LukeA]

wow! that is awesome. i think i better work on my tail light set up first. that looks a little bit more complex. also i'd have to make it work in the bulb holder it has so that it would still have the reflector. right? let me think about this one!
thanks

Soldering-wise it's probably simpler (really, there's nothing to it), but with high-flux LEDs there are physical considerations, namely how to remove all the heat.

 

[frenzee]

Red LEDs typically have a forward voltage of 2.0 volts. White LEDs have a Vf of 3.2-3.4V. If your electrical system has a lead-acid battery, then your supply voltage should be around 13.2V. For typical 5mm LEDs sold at RS or on eBay, you should limit the current to 20 milliamps.

Use this calculator to plug in your values and you'll get a resistor value of 68 Ohms for the red cricuit and 320-390 Ohms for the white circuit.

Hope this helps and good luck with your project!