This instructable is created and provided by the Edmonton Bicycle Commuters' Society (EBC) (http://edmontonbikes.ca , http://www.facebook.com/edmontonbikes , http://twitter.com/edmontonbicycle ), a non-profit organization that supports all cyclists in Edmonton ...
EBC also operates BikeWorks, a fully-equipped, volunteer-run community bike workshop, where volunteer mechanics teach & help members of the public to learn how to fix their bicycles. EBC also sells used bikes.
This is the introductory video to building a high-power three LED bicycle light. The design here has 3 modes: High, Medium, and Strobe (blinking), and runs on a voltage between 5-10V. The price of the light, including batteries, charger, and worldwide shipping, is about $50 US. Including batteries, it weighs about 200 grams, and should last about 1.5 hours on high mode (and significantly longer on medium or strobe modes).
This light is something that you can build with minimal investment in components and small hand tools. You don't need to know electronics: there are just 18 solder points, 6 drill holes, a bunch of hot glue, and a few screws. It doesn't require a microcontroller. You don't need to know what an Arduino is. It doesn't require you to fabricate metal, use PVC tubing, laser cut anything, or weld. With a bit of experience (e.g. if, for whatever reason, you make a half-dozen), you can put one of these lights together in less than an hour.
The Edmonton Bicycle Commuters' Society occasionally runs in-person courses on designing and building your own custom bike lights: this design or one customized to suit your needs.
This light works in thunderstorms, blizzards, and has been used in temperatures below -30C.
That power source can be two lithium-ion rechargeable batteries, or four to six alkaline 1.5V cells in series, or five to seven rechargeable NiMH or NiCad 1.2V cells in series (any of AAA, AA, C, or D shapes). A 6V generator would also work, provided it can provide about 9-12W of power (this is a bit high for the average bike generator).
Two wood/metal screws, 10x1/2 plated steel, pan, button or round head (any hardware store)
Two small springs (scavenge these: in a pinch, you can use the spring from a pen and cut it in half, but if you can find a stiffer spring with a slightly larger diameter, it would work better. Springs from existing battery holders [e.g. for AA battery operated devices] can work well.)
=== TOOLS (if you don't already have them or can't think of a way to fake it) ===
[DX sku.22264] ($4.63) - 30W soldering iron (110V AC)
[DX sku.10018] ($12.07) - Digital multimeter (if you already have a multimeter, but it doesn't have a connectivity testing mode, you can just measure resistance. A resistance of nearly 0 Ohms is the same thing as a connection, which is the same thing as a closed-circuit, which is the same thing as a short circuit.)
Foil duct tape (available at any hardware store)
Hot air blower or lighter (for the heat shrink)
All DX parts can be purchased from http://www.dx.com/ . Prices there include worldwide shipping. You may be able to source equivalent (or better) parts for less money, or make substitutions, but I've provided the DX numbers to make things easy for those that just want to follow a detailed shopping list and know that all the parts will work together. When ordering the part numbers listed above, you'll end up with extra components, since some of them come in multiples.
Be warned: I have waited up to 4 months for parts to arrive from DealExtreme. I've always received my items, or received my money back if they couldn't ship it or shipped a wrong/defective item. But some times it's a long, frustrating process. They don't make you jump through hoops, but they can be extremely slow to respond.
They're pretty much a lousy retailer and unacceptable by any normal standards, but if you want to save a few pennies and not leave your house, and you can afford to wait potentially forever, they might barely satisfy your needs. If you work at it, you can often find the same (or better) items on eBay for less money.
(Apologies for the focus. Still learning how to use my camera.)
Step 1: Clip away the four plastic protrusions/tabs at each end of the box (where the battery terminals will sit).
Step 2: Drill a small hole above each point where you clipped away the plastic. Drill as high as possible so that your battery-holder terminals will be near the centre of the battery terminals.
Step 3: Ensure that your screws and springs are conductive using a connectivity tester. If your multimeter doesn't have an explicit connectivity tester, you can measure resistance instead. A resistance of 0 Ohms (or under ~4 Ohms) is the same thing as a connection, which is the same thing as a closed-circuit (which is the same thing as a short circuit). This is what you want between the head of your screw and its tip.
Step 4: Drive one screw into a hole from the inside of the battery box. Drive the second screw into the opposite corner.
Step 5: Use pliers to pull open one end of the spring and feed it into one of the remaining holes, from the inside of the battery box. Turn it through about a turn and a half. Do the same with the other spring.
Step 6: Check to see if your batteries fit your battery box. If not, make appropriate adjustments of the springs and screws. Make sure you didn’t skip Step 1.
Step 7: Remove the batteries. You must not try to solder with the batteries still in the case.
Step 8: File the tips of the screws down so that you don’t stab yourself. This is an optional but recommended step.
Step 9: Strip a short piece of wire: strip about 1 inch from one side, and 1 cm from the other. Wrap the long stripped section at least one full turn around one screw, so that it wraps back on itself. Twist the other end of the wire around the nearby spring. Solder both in place. Make sure that the solder connects your wire loop on the screw. Test that the screw is electrically connected to the spring, using your multimeter. Touch the probes to the screw and the spring (not to your solder or the wire--you don’t want to bypass your solder points).
Step 10: Cut two wires, about 6-10 inches in length (speaker wire works well here because it comes paired already). If your wires are differentiated, select which colour will be your positive wire and which will be your negative. Strip one end of the “positive” wire about one inch. Wrap it around the screw and solder it. Strip a short length of the “negative” wire and wrap it around the spring. Solder it too.
Step 11: Strip short lengths of the other ends of the wires. Test the connectivity of these to the screw, spring, and each other (they shouldn’t be shorted to each other).
Step 12: Write polarity signs on the inside of your battery box. Screws are +ve terminals, springs are -ve terminals.