Posted - 03/01/2007 : 16:17:48
| The purpose of this thread is to provide information to anyone who wants to use LED's on their PW projects. Please post if you have information to add but try to avoid asking questions here. We will be glad to answer questions in other threads.
*LED's offer sufficient and sometimes tremendous amounts of light with very low current draw and low heat compared to other lights.
*They are rugged, come in different sizes and many colors.
*Some existing products suitable for PW use are flashlights or dot lights for headlights and marker and tail lights for other applications.
*They are small, so they can be used just about anywhere.
*No reflectors required. Beam angle is determined by the LED itself.
*Low current means thin wire (20-24ga is fine for most applications) and low power resistors can be used.
*You don't have to run them off the main power source in your PW. You could use regular AA or C size batteries if you wanted to and they will still last a long time.
WHY NOT LED'S---
*They can be expensive. If you get ready made products from a local auto store, expect to pay more for LED's than other types of lighting. If you get them online, you may have to order more than you need, thus making them a larger initial investment.
*LED's are electromagnetically sensitive. You need to be careful of static electricity when working with them.
*They produce intese light at a concentrated point. You don't want to look straight at them at close distances. If using them for accent lighting or other direct viewing applications, beware and run them at very low current levels.
*Making circuits may involve some math (although online wizards can be used as well)
*Headlights...Go for 5mm or 10mm white LED's with a narrow viewing angle (15-25 degrees). Use several depending on how much light you want. To be able to drive in the dark you will probably want at least 3 high brightness LED's per headlight. You could also use a high power "star" or "emitter", but these run a lot of current and absolutely must be connected to heatsinks to be used to their fullest.
*Tail lights/accent lights/underbody lights/other decorative applications...Use 3mm, 5mm, 10mm or superflux (piranha) LED's. They come in all kinds of different colors. For these applications, either get wide angle LED's (60 degree or greater) or modify regular ones. You can sand the top and sides of the plastic to diffuse the light, or simply sand the tops flat. This will eliminate the narrow beam.
WHAT DO I NEED TO KNOW---
*LED's observe polarity, so be sure to connect them correctly or they won't light up. If hooked incorrectly they may die quickly. Usually the lead with the "cup" inside the LED is hooked to the negative terminal of a battery. This is usually the shorter lead.
*Don't hook them up without the correct resistors. A wizard to help you figure out values is here http://led.linear1.org/led.wiz
*Pay attention to the specs. Different colored LED's run on different voltages, so don't mix and match in your circuits.
*Typical 5mm LED's like to be run at 25mA or less. A good number to stick with is 20mA.
*You need to know how to solder (or use butt connectors, but they are expensive and bulky) and may need heatshrink tubing.
*The newer superflux package offers better heat dissipating qualities than standard 5mm package.
*When designing your own circuit, try to take advantage of voltage and run as many lamps in series as you can. This will simplify wiring, use fewer resistors and convert more energy into light instead of heat lost in the resistors.
*Beware crazy claims of huge mcd ratings. Understand that mcd is intensity at a single point and does not represent total light output very well.
*Stick with known vendors with good ratings. I have used JELED electronics (HKJE on eBay) and have been satisfied. Others are Best Hong Kong, Spectrum LED's, LS Diodes, Light of Victory.
*Do some research. A few links to sites with forums and other good info are listed below.
Hope this LED you down the right path. (Sorry, I couldn't help myself)
Edited by - swhenrik on 10/03/2007 15:03:03