This instructable describes the construction of a bike light comprising three 3W Luxeon LEDs. This project had three main goals. 1.) Make a light suitable for use in 24-hour mountain bike racing. 2.) Use readily available material as much as possible. 3.) Offer the details to the community and invite any and all comments. I originally published this project at this site: http://www.racedaynutrition.com/features/bikelight.aspx
Step 1: Basic Hardware
Pictured here are some of the basic hardware items required for this project. On the left is a 5W halogen light from a VistaLite system (ca. 2000) from which the handlebar mount will be salvaged. At top are radio controlled helicopter motor or "280" size motor heatsinks. The other items follow the goal of using readily available material: 3/4" copper plumbing caps, 1" corner irons, and a 2" long binder clip. See Step #3 for a parts list.
Step 2: Electrical Components
Pictured here are some of the specialty electrical items necessary to make any high quality Luxeon LED light. The two small toggle switches are available at your favorite local electronics supply store. The funny-looking things in the lower left are 2009 Micropuck LED drivers. Add these to the shopping cart when you order the Luxeon LEDs. Finally, the syringes on the right are tubes of Arctic Silver two-part thermal epoxy. This epoxy is the most exotic part of the project. See Step #3 for a parts list.
Step 3: Parts List
Below is a list of items required for this project.
Quantity - Item Description - Suggested Supplier
3 - Luxeon III Star, White, Lambertian - ledsupply.com
3 - Luxeon III Star Optic Holder, White - ledsupply.com
2 - Optics, Collimating 10 deg - ledsupply.com
1 - Optics, Narrow beam 15 deg - ledsupply.com
2 - High-Output Micropuck Drive Module - ledsupply.com
1 - Arctic Silver Premium Thermal Epoxy - ledsupply.com
2 - Micromini toggle switch - radioshack.com
3 - Aluminum Heat Sink for 280 Motor - trossenrobotics.com
3 - 3/4" Copper Plumbing Cap - Local Hardware Store
1 - 1" Corner Irons (package of four) - Local Hardware Store
1 - 2" Long Binder Clip - Local Office Supply Store
1 - Tazmanian Devil House Key - Local Hardware Store
Miscellaneous Hardware - Local Hardware Store
Miscellaneous Electrical - Local Hardware Store
Salvaged Handlebar Mount
Step 4: Key Components: Durable Housing and Heat Sink
This is the key element for the whole DIY bike light. Luxeon LEDs, especially 3W and higher, require supplemental heat dissipation. Without proper conductance of heat away from the diode, it will overheat and fail. At the very least, the LED will operate with reduced efficiency. It just so happens that a Luxeon Star LED fits conveniently inside a 3/4" copper plumbing cap. It's quite possible that the cap alone will provide enough heat dissipation for 1W Luxeons. For 3W and above the additional aluminum heat sink can only help.
Step 5: Soldering Skills
You'll of course need a soldering iron. As you might expect, soldering requires some skill. But don't worry, with just a little practice anyone can learn the process. For some extra help getting started, take a minute to watch the Soldering Tutorial video at Makezine.com: http://www.makezine.com/blog/archive/2007/01/soldering_tutor_1.html
Always wear safety glasses when soldering. Molten metal + Eyeball = Bad. Enlist the help of acid paste flux where appropriate.
Step 6: Destroy Office Supplies!
At last, a chance to unleash your aggression on office supplies! Measure and mark locations to mount the toggles switches. Position the clip in a vise and drill until your heart's content (or until there is a hole). In this case there will be two switches: one powers up the top LED, the second adds power to the bottom two LEDs so that all three LEDs are on. For different ambient light and riding conditions it is useful to have some control over illuminating your path.
Step 7: Starting to Take Shape
In this step, take a moment to fit the 1" corner iron into the clip. Push one toggle switch through the existing hole (you will probably have to enlarge it) and mark the corner iron for drilling a second hole. Did you know the binder clip was invented in 1911 by Washington DC native Louis E. Baltzley? Drop in at Wikipedia for a little history lesson: http://en.wikipedia.org/wiki/Binder_clip
Step 8: Fit It Together
Get an idea of how to position the Luxeon Star and optics holder inside the copper cap. You'll want to put holes in the side of the optics holder with the most vertical surface area. In the photo, this is the side lined up with the gap in the heat sink.
Step 9: Marking Holes for Drilling
Check the alignment between the LED housing and the binder clip. Mark the binder clip at the point of contact with the copper cap. This mark will be where you need to drill holes in the clip. Three holes are required per LED housing: two for the screws and one to feed the wires through.
Step 10: Insert, Align, Mark, Remove, Drill, Repeat
Modifying the copper cap is an iterative process. Before modifying the cap, place the Luxeon Star and optics holder inside. Decide where it would be most appropriate to drill holes for the screws. Remove the Luxeon and optics holder and drill the screw holes in the cap. Now reinsert the Luxeon and optics holder and align according to the steps above. Mark the optics holder, remove, drill optics holder. Reinsert, add screws, and decide where it would be most appropriate to drill a third hole for the wires. Remove, drill hole & you get the idea.
Step 11: Drill Baby, Drill
I know what you're thinking, "How am I going to fit three holes in this thing?" Trust me, there's room. In fact, if you look closely at the photo, this particular cap was generous enough to accommodate a half dozen holes! The point is, if you're not happy with the position of the holes, just rotate and try again. Don't forget to file down the rough edges before moving on. The insulation on the wires will thank you later.
Step 12: Pretending to Be a Machinist
Here the builder is fantasizing that when he drills the next copper cap, the holes will actually be in the same positions as the first. Do the best you can here. To the amateur, small drill bits bend and wiggle all over the place when drilling on the outside of a cylinder. Allow yourself some loose tolerances and you'll have no problem.
Step 13: Fun With Grinding
Put on your safety glasses and fire up your favorite grinder. In order for the top LED housing to fit on the binder clip properly, two fins of the heat sink must be ground off. With aluminum, this task takes little time. The photo at right illustrates that precision grinding is not a requirement.
Step 14: The Sphinx
Perfect fit! With two heat sink fins removed, the top LED housing is ready to be mated to the binder clip.
Step 15: Let There Be Light
Solder lead wires to the LEDs. Wear your safety glasses and make sure you haven't had too much coffee. You'll need steady hands for this task. Actually, the Luxeon Stars are designed with generously sized, pre-tinned contact pads making this step easier than you may think. (Note: "generously sized" is a relative term.)
Step 16: Wiring Diagram!
The wiring diagram! This was adapted from the Micropuck Applications PDF referenced in the next step. The diagram pictured here is the way this bike light is wired. Click here to see a larger image: http://www.racedaynutrition.com/images/bikelight/wiring_diagram_fullsize.jpg
Step 17: Buck/boost Configuration
The Micropucks are wired in parallel in order to properly power 3W Luxeons. In the LED driver world, this particular parallel config is known as "buck/boost." It offers a wide range of input voltage (1 - 7V) and will effectively power the LEDs until the battery is exhausted. The parallel buck/boost config nearly doubles the current over a regular boost config, but sacrifices some efficiency. Click here: http://www.ledsupply.com/docs/MicroPuck-Applications.pdf to visit an excellent document prepared by LEDdynamics, Inc. illustrating applications of the 2009 Micropuck. The configuration used in this project is described as "Two 2009s in Parallel, Buck/Boost."
Step 18: Prepare for Epoxy
Connecting the Luxeon Star to the cap is important for two reasons: One, you dont want the LED to fall out. Two, you want heat generated by the diode to transfer to a heat-dissipating object. Epoxy is used in this project because it eliminates the need to drill more holes in the copper cap and it offers a lot of heat transfer surface area. As you know, most epoxies like a clean surface area in which to bond. Clean the cap by putting a drop of rubbing alcohol on a cotton swab and wipe away any dirt and/or oil.
Step 19: Attached Forever
Mix up and apply some thermal epoxy and smoosh the LED against the inside back of the copper cap. If you're using Arctic Silver, or any similar product here, I'm confident you read the instructions. Check your receipt and you'll know why I am confident you read the instructions. This stuff ain't cheap. You don't want to mess up. You think a gallon of gasoline is expensive? If you were to buy a gallon of Arctic Silver, it would set you back $9834.50. (No kidding, $12.99 for about 5ml) Oh, and among other things, it's photo-sensitive. So don't leave it exposed under the florescent lighting of your workbench all afternoon. So, why use Arctic Silver? Because Section 2 of the Arctic Silver instruction manual states, "There is a very good chance that any components you attach with Arctic Silver Thermal Epoxy will stay attached forever."
Step 20: Relax!
Take a break after adhering the Luxeon Stars to the copper caps. This will allow time for the epoxy to sufficiently harden and for you to relax after the stress of working with the most expensive glue you'll ever handle. Next, slip the wires through the optics holder, insert the #4 screws, and see how everything fits.
Step 21: Snug Fit
Mind the gap. If it hasn't occurred to you already. Everything in this light comes together pretty snug. Before going any further check to see that the LED leads are not touching the screw. This could lead to a short or at least an LED that doesn't light. If the wire is not touching the screw but looks close, it might be wise to drop in some non-conducting epoxy between them. But, before you do that, read the next two steps.
Step 22: Bend a Washer
The O.D. of the optics holder is a bit smaller than the I.D. of the copper cap. If you fit the LED housing to binder clip, the optics holder will be off center. Avoid that issue by inserting a thin washer between the optics holder and the copper cap. Bend the washer to fit.
Step 23: Insert Washer
Slide the curved washer in between the optics holder and the copper cap.
Step 24: Coming Together
Proceed with the steps above until you have all three LED housings assembled and ready to bolt to the binder clip. Take your time and think through each step. When ready, pull the leads through the previously drilled holes in the clip leaving some slack on the LED side. Use the #4 screws to attached the housings. Using thread lock compound here is a good idea. Shape the wire in the optics holder in order to accommodate the optics.
Step 25: Stuff It!
Connect the Micropuck according to the wiring diagram in Step #15 and stuff it inside the clip. For this project, the two Micropucks were intially epoxied together. However, in order to accomplish this step, the pucks had to be seperated. It's a tight fit and it's only going to get more cramped!
Step 26: Locate Your Magic Wand...
Connect the toggle switches according to the wiring diagram in Step #15. Using acid paste flux really helps to get the solder to bond to the switch leads. Don't forget to slide heat shrink tubing on your wires ahead of time. When finished, cover any exposed wire or switch leads with non-conductive epoxy. Next, locate your magic wand and get ready to mount the switches inside the already-packed binder clip.
Step 27: Almost Finished!
Behold! The switches magically insert themselves into the clip! Oops, how do I edit out the binder clip handles from the photo? Seriously, this is a tricky step. It's nearly impossible without prying open the binder clip. What better way to open the clip than to use is as it was originally designed? With the lights bolted on, the clip will only open partially. But, that is all that is needed to finish this step. Patience is the key. Don't forget to add a drop of thread lock compound to the toggle switch threads.
Step 28: Pièce De Résistance!
To protect the internals from the elements, the bike light requires some kind of rigid, triangular-shaped piece on the front. What could be more appropriate than a Tazmanian Devil enameled house key? After a few minutes work with the grinding wheel, the head of the key was shaped to fit the opening in the clip. Also picture here is some hardware required to attach the handlebar mount. The neoprene washer may be used to help waterproof the opening in the front of the clip. For some positionability of the light, use salvaged bicycle brake pad washers. They are curved to allow a bit of a swivel motion before tightening.
Step 29: Salvaged Handlebar Light Mount
In this photo you can see how the salvaged Vistalite handlebar mount is attached to the corner iron.
Step 30: Done!
The bike light is now fully assembled. Well, except for batteries and a battery connector. I'll leave that up to you. In this photo the lenses are snapped into place. On the top is a regular 15 degree lens. The bottom two LEDs feature 10 degree collimating lenses.
Step 31: Old 5-Watt Halogen Illumination
5-Watt halogen light (shown in step #1) powered by 6 Volts. Photo taken at a distance of 20 feet with 1.3 second shutter delay.
Step 32: Single 3-Watt Luxeon Illumination
Single 3-Watt Luxeon III with 15 degree lens powered by 6 Volts. Photo taken at a distance of 20 feet with 1.3 second shutter delay.
Step 33: All Three 3-Watt Luxeon Illumination
All three 3-Watt Luxeon III's powered by 6 Volts. Photo taken at a distance of 20 feet with 1.3 second shutter delay.
Step 34: Recommendations
1.) A Luxeon III Star can handle 1400 mA. The High-Output MicroPucks used in this project combine for 700 mA. At 700 mA, a single Luxeon III Star has a luminous flux of 65 lm. Use Super High-Output MicroPucks for a combined 1000 mA output. At 1000 mA, a single Luxeon III Star has a luminous flux of 80 lm. Brighter light, same price!
2.) Reposition the handlebar mount to some point beneath the light. This will help balance the weight and should allow you to swivel the light without using brake pad washers as described above.