Just a warning for the patience-impaired: I explain my reasoning a lot in this, so that you can make your own choices about things easier, which greatly lengthens this instructable. If you don't like long detailed articles, you should stop reading now, as there is no condensed version of this available (nor will there be) due to it's nature (and my writing style). :-) You probably won't want to look at my Electricle" bike motorization project blog, either, which is where this project and article evolved from.
I've read Instructables for a long time, but never contributed until now. I'm sure this instructable needs improvement, and I may revise it considerably depending on feedback, but keep in mind that this particular thing can't be made as specific, instruction-wise, as an instructable really should be made. Any constructive feedback is welcome, though I may not be able to implement it all.
Here's how to make your bike safer to ride at night (and even in the daytime!) while recycling some old computer parts you may have laying around. My specific goal was to use only recycled parts if it was at all possible, and so that's what I did for almost everything except for the LEDs. I've included instructions on how I did this with the parts I had available, but because this instructable covers a basic idea rather than something with a very specific parts list, you'll need to do some work on your own to figure out how to disassemble/assemble some things, based on the parts you actually use for your lights.
Mine is intended to be daylight visible simply because around here, not many people seem to know what hand signals mean (they were not even on the drivers' test last time), and fail to comprehend why I'm "waving my hand around". :-( Even a few law enforcement officers do not seem to know what they mean. However, *everyone*, driver, pedestrian, cyclist, etc., knows what the lighted signals on vehicles mean (even if they don't actually *use* their own signals), so when I use those, I have no problems riding in traffic as *part* of traffic, safely, day or night. It also keeps both my hands on the bars, which is safer given the road conditions in many places here due to "construction". The goal is not to have them blindingly bright, but simply at least as visible as a motorcycle. If they are too bright at night, they will simply blind someone momentarily, and may end up causing the accident you were using them to try to avoid.
Sourcing the parts is easy, even if you don't have something yourself laying around that will work, as Ebay probably has some if you don't mind the price. I don't recommend that, simply because it will cost you a lot to do this in the end. If you are patient, you can probably gather all the parts (except LEDs) for free from your local Freecycle.org mailing list groups. I see stuff that could be used for this at least once a week or so on one or the other of the local Phoenix, AZ Freecycle lists, which have a few thousand members total, giving away old stuff they don't need anymore.
I used the slide/film-negative backlight adapters from an HP and a Microtek scanner as the base units simply because I had the HP already, and found the Microtek for a couple bucks at a thrift store. Any of these units that has a bar shape and a reasonably large surface area for the white fluorescent light in them can be used.
The Philips LumiLEDs are all new, and the most expensive part of the project--almost everything else can be taken from recycled parts, but you're unlikely to find the LEDs that way, unless you get lucky in an automotive junkyard and run across a car with LED signals that haven't already been stripped off or crushed in whatever accident placed the car there in the first place. Make sure you order *actual* LumiLEDs, and not the knockoffs; there is a huge difference in the brightness and current between them--I had some of both due to a vendor mistake, and the knockoffs are not nearly as visible in daylight, while the LumiLEDs easily are. Unfortunately they are SO bright that regardless of settings and distance from them, my little Sony digicam cannot distinguish the difference :-) so I have no comparison images. As it is, it's hard to see the difference in color between the red and amber ones, though there is absolutely no question about it with your own eyes.
The basic concept is that you will use the actual fluorescent light in the scanner adapter as a headlight, running from 12v (most are already 12v; some are 9v but will run without issue on 12v for years, and are brighter that way, a few will burn out if you use higher than rated voltage, so test carefully and at your own risk. ;-) ). Installed in the ends of the casing are the front turn signals, which are also the marker lights. In some of the unused space inside the casing will be the turn signal electronics, which are very simple.
The taillight has to have the fluorescent light removed (save it as a spare for the front one, especially if it's identical), because using a red gel or other filter on a fluorescent light won't get you enough usable light to be worth it, compared to LEDs. So you'll be adding an array of red LEDs in the taillight casing, and four strips of LEDs at the ends, one facing the side directly, and one facing the rear directly, on each end. The electronics to switch between these will all be inside the casing as well.
The handlebar signal switch can be any switch that has a center-off and toggles to one position on each side of that center. It can be vertically or horizontally mounted. Since I had one already, I used a pre-existing electric scooter's turn signal switch, because it is already in a handlebar mount. (Remember, my goal was also to use as much recycled material/parts as possible). I don't recommend using a stick-type toggle switch, as it's far too easy to break it off or damage it if you need to turn the bike over for changing a tire or servicing it when on the road, depending on where you mount it. It's also possible to accidentally catch your riding gear on it, or a shirt sleeve, etc, and either hurt yourself or tear the shirt. The rocker switch type is much better, but it is difficult to find them in weather-sealed versions when using recycled parts, so you might have to modify it with a bit of sealant to fix that, or simply accept that it might have to be replaced or cleaned due to water/etc.
Thewalkaround video below shows the lighting system in my living room, with no other lights except that.
This second video (steady shot from left rear of bike) shows the turn signal running, just after nightfall in my "carport". Behind the camera is a typical mercury-vapor streetlamp, and to the left of the bike is a covered up junk car for project parts, just visible from the light of the bike lamps.
The first pics below show the bike lights in comparison to a typical car, in a parking lot with a closed and half-darkened store behind them, and a typical mercury-vapor streetlamp off to the side and above. Keep in mind the battery for the lighting system hasn't even been charged in over a week before these images, and is nearly to the point where the longer LED strings will stop lighting (this actually happened on the way home, due to my forgetfulness, thankfully since the rear signals are shorter strings they still worked fine). Yet even so, they're bright enough to be noticeable here. They're several times brighter on a full charge.
The second (new) set of pics are in my carport, taken the same day as the second video above. The pics are in 4 sets, from just before sunset (on the other side of the house from the carport, so no direct sunlight shown) to just after nightfall, and show the bike from each side, with the left turn signal blinking. Where possible, there are images from each lighting condition and angle both with and without the signal, but because the camera has an unpredictable short delay after pressing shutter button and actually capturing the image, I could not get a shot of each even after dozens of tries. I did get many in-between states, oddly enough, where one LED set was in the process of dimming, and the other just beginning to light, which is very strange, since that time period is *extremely* short, compared to the time each LED set is actually fully on (see the video for example timing). None of the in-between pics are posted, as they're not important to how the light works. :-)
Step 1: Picking Your Parts
First up are a few guts from various scanners and lids. The one with no casing at all, just bare bulb, is out of the actual scanner mechanism that moves in the tray under the glass. The small rectangular thin one above it in the same pic is from the lid of a scanner, for use with slides, transparencies, negatives, etc. The lid was quite flexible and flimsy, so I didn't save it with the light. Same is true of the casing for the bottom light, which came out of a bar-style filmstrip adapter a lot like the one on my actual bike headlight. The light is shorter than the other bar style one I used, and thus less surface area and less bright, which is the main reason I didn't use this one. It *would* have let me put the front-facing LEDs in, though, which I couldn't do with the headlight I ended up with. All of these shown here run on 12VDC, and take anywhere from about 250mA to 700mA. That's a lot of power, but it's also a lot of light.
The next few pics show how thin the one small unit is, and what it looks like with the light off and on. Given that it's the 250mA unit, it's pretty bright. The kitchen lighting I took these images in is 160W (4x 40W 4-foot tubes, no diffuser), directly under the light, 4.5 feet over the table. The image that shows it powered on with the light in the center of the camera was bright enough to force the camera to iris down and dim the background to not overlight the center where the CCFL lighting is. To show better how it looks side by side the next two pics show it off and then on with the camera focused outside the area the light would cause to iris down. It's not too bright, compared to other scanner adapters I've used, but it's ok for it's size.
The next series of images shows a much larger scanner adapter, which is about the size of my outstretched hand. It came off an HP, and also runs on 12V, but takes closer to 1Amp. I have an identical one I've used as a reading light for several years, and is bright enough to be uncomfortable to look directly at in an otherwise darkened room if you're within a few feet (though it does a good job of lighting the room itself). This shows you the sequence of taking it apart--the screws you see in the corners of the frame are just philips, and all that holds it together beyond that is some small clips on the edges of the gray rear casing.
It is pretty thin, about the same as my hand resting comfortably on a flat surface, but due to the way it's made it has a lot of room inside. You can see the thin (1/4", perhaps) light module itself on it's face in the upper left of the fully-opened image. The next one shows an oblique angle across the inside of the casing, exhibiting the depth of the casing where you could put your other electronics.
After that are the PCB and components, showing that despite the thick cable with multiple wires, it only has two electrical connections, one for power (red) and one for ground (all the rest of the wires). You could readily cut the main connector off and use the short cable left to run to your battery, if it is also on the handlebars or at the front of the frame. Otherwise, you'll need to remove the external cable entirely and splice in your own power cable, which is what I had to do on my existing unit.
There is a great variety of these things out there, and many people have scanners that came with them but never ever ever use this part. If you're one of those people, now is your chance to make it serve some purpose besides helping it's box obey the law of gravity. If not, you may know someone like this, or be able to find one easily for next to nothing in a thrift store, or on Freecycle.org. That's where all these came from--someone else's throwaways.
Keep in mind that whichever one you find and use, it should have enough room inside for the parts you're going to install. Preferably with enough front panel area not used by the light module that you can mount a decent surface area of LEDs on, but if, like the large square one shown above, there is no existing leftover front surface, you can still add them onto the side edges, some facing forward,some to the side. Or you can use totally separate casings for them (it's just easier to have them all in one casing for mounting purposes and wiring).
Another consideration is how easy it is to weatherproof the case. Most are very easy--you only have to apply a very thin bead of silicone sealant to the mating edges of the case where it meets the plexiglass or other diffuser, and also at the cable entrance and back/front casing edges. Just make sure everything is working before you seal it up if you choose this method, as it's hard to get them apart again (though not impossible).
Step 2: Disassembling the Headlight Casing
Unscrewing those, and setting them aside for later reassembly, allows easy removal of the black plastic cover that holds the rest of the light module together. This cover (on mine) has the milk plex diffuser simply sitting in place, and it will fall out when you take the cover off. Behind it is the fragile cold-cathode fluorescent bulb (CCFL), inside a reflector. Try not to touch the bulb if possible; too much pressure will crack it, though it will flex rather a lot more than you might imagine. Mine has survived innumerable bumps and scrapes and even full drops of the bike on the pavement, including a direct impact of the lighting unit with a post as it fell over while I was chaining it up once.
The inverter powering the CCFL is often screwed to the back of the reflector, and doesn't need to be touched or modified in any way. You only need to avoid placing any of your own electronics where they can contact it; this is important because the biggest space in this unit is right behind that inverter, and is probably where you'll put your electronics if you have a similar module to use.
Decide now which is the right end, and which is left, and mark that on the casing (simply using a marker on what will be the bottom outer edge is good). This is so that during building, testing and later during mounting you have no question over which is which. It'd be frustrating if you ended up with the right side flashing when you turn on the left signal. :-)
The ends of this particular unit happen to be just far enough from the reflector and just wide enough that the LumiLEDs fit easily into a slot cut for them. My current version, as built, has only one row of eight LumiLEDs, but was planned to have two, as the side bar is wide enough for them. This was not done simply because I didn't have enough of them at the time, and because the signals are actually visible in daylight even with only eight of them. It would be better with more, obviously, but it is up to the builder.
Cutting the slots for the LEDs can be done by hand with a utility knife or Xacto, or using a Dremel at low speeds (high speeds will just send molten plastic blobs flying, and they'll hurt you!). The unit I have is made of ABS plastic, so it took a little more work than a simple styrene case would have to cut thru.
I recommend first measuring your particular unit by holding up an LED to the inside of the casing to see how many of them you can fit in the space available, and then cutting a slot that is *exactly* wide enough for the row or column of them you're going to use. Mine were one LED wide, and eight high.
If your reflector does not go all the way to the ends, you can make two sets of front marker/signals, as will be done in the rear, and have one set face forward and the other face to the side. Mine was not quite enough space to do this because of the screwmounts and case wall thickness, so I used the side ones only, angled slightly forward, so they could be seen from either front or side.
The pics below show some of what's described above, for the light module I had already been using as a headlight for months before adding turn signals and marker lights to it.The first pic shows it as it is now, with the lights on in a typically lit livingroom. The lights are so bright that the camera's autoiris function dimmed down the rest of the lighting to make it look like an otherwise unlit room.
The second just shows it as it originally existed, but painted and with a reflector covering a spot that had no plex to let light thru (even though the bulb itself goes the entire length). Next pic shows the front cover off, with the plex laying in the cover tray and the CCFL bulb and reflector visible. Fourth is the space behind the reflector, showing the inverter electronics mounted on the back of it, and my not-very-good wiring job inside (I was in quite a hurry when I originally made the headlight, and only cared that it worked, but since it never failed I never went back to clean it up). Last shows the unit from the side with some of the LEDs mounted and lit, but the front casing and CCFL not yet on.
You can see that there is a rocker switch mounted in the top edge of the unit--that's the power switch for all the lighting. Makes it easy to reach when riding. It's not sealed, as it's a switch recycled from a cieling fan wall-mounted control box, and eventually I'd like to replace it with a sealed switch. For now, it works, and hasn't actually ever had a problem, even in pouring rain (unlike the cheap brake lever switch).
Step 3: Assembling LED Units
First, there are two good ways to get the power to your LEDs in a safe way that also keeps them at max brightness. The way I chose for it's simplicity and ability to do without buying parts to do it (or building PCBs) was simply to calculate and use current limiting resistors for each string of LEDs. The way I would do it if I could would be to use one of the LED driver chips designed by Maxim or TI, etc, that create constant current in the LED string regardless of supply voltage, even if it drops below the voltage the LED string requires (by boosting it up), and which can also be used to dim the LEDs, as this would allow for a much much brighter daytime LED array, with an ambient light sensor that forces the LEDs to be dimmed proportionally to the ambient light, so as it gets darker the lights are dimmed so people aren't blinded by them, and they are then safely just as visible in the daytime as they are at night. This instructable doesn't cover doing that, but if you are capable of making surface-mount sized PCBs, the chips those companies (and others) make for automotive and home lighting use have reference designs in their spec sheets that you can use to build even better lighting and signalling than I have here. :-)
Each LED is 2.0VDC forward voltage drop, so you should plan your wiring of the units based on the idea that you will have some small operable range of voltage for your system, preferably by regulating the voltage from the battery in some way, so that the LEDs don't get overcurrented and damaged or destroyed, but also don't just suddenly go dim on you while riding because your battery didn't last long enough (dropping it's voltage below the chained-together voltage amount). Remember, though, that regulating the battery voltage with any of the linear regulators (like a 7812) will waste a lot of power as heat, and will also simply stop working altogether as soon as the battery drops below the regulator's input minimum. So I didn't use regulators.
That sounds kind of confusing, so think of it like this. I used a 12V 7AH SLA battery simply because I had it nearly-new from a weedeater with a burned out motor, and it had a simple charger I could readily move to the bike (self-contained wallwart style). That means I could use 6 LEDs at 2V each to utilize that 12V, but as soon as the battery runs a little low, they'll all go dim very fast because there's not enough voltage to get them to draw the current needed to light up properly. Using 4 or 5 LEDs would give me 8V or 10V with either 4V or 2V to spare, and you shouldn't really drop an SLA below 10V anyway.
There will need to be current limiting resistors on each series strip of LEDs, limiting it to 70mA (for LumiLEDs) at the highest voltage the system will ever be at (usually around 13V for a fully properly charged SLA). Ohm's Law says that for 4 LEDs of 8V drop, leaving 5V max "unused" voltage that will be across the resistor, you'd get 71.428 Ohms for the resistance that must be in series with them to ensure the LEDs never get more than 70mA current. For 5 LEDs, that's going to be 57.143 Ohms. For 3 LEDs of 6V drop, leaving 7V across the resistor, you need 100 ohms
The resistors have to dissipate waste power as heat, so for 5 LEDs that's going to be 5V x 70ma = 5V x 0.07A = 0.35 Watts. A little more than the standard 1/4 watt resistors are meant to take, so just in case, you should parallel two resistors of double the value calculated above for the 4-LED strings. Since the 5-LED strings end up with 0.28 Watts to dissipate, they should also be done this way, but are close enough to the 0.25 (1/4) Watt rating that if you have them mounted against something that will help them carry off that heat from the actual resistor bodies, they'll probably survive the life of these units without catching fire or damaging them. Optionally you can use 1/2 Watt resistors, but they're not as common to find in various junk electronics you probably already have laying around to pull from. :-) A 3-LED string ends up with 0.42 Watts to dissipate if using the 100-ohm resistor.
Since 150 Ohms is a common resistor value, you can parallel two of them to get 75 Ohms, which will be close enough for the 4-LED strings to get them to almost their max brightness without ever damaging them. This also means that if all you have is 1/4 Watt resistors, paralleling two of them also gives you that ~1/3 watt power dissipation needed, with a safety margin. For the 5-LED strings, there are 51 Ohm and 56 Ohm resistors, but neither is good enough, because they're *lower* than the value you need, which means both over-currenting the LEDs *and* dissipating even more power thru the resistor, bringing both parts closer to being able to fail easily. A 120 Ohm resistor is available, though, so I'd use two of those in parallel for 60 Ohms total, which will make the LEDs a bit dimmer than their absolute max, but also still very very bright. You probably wouldn't see the difference even with them right next to each other. The 100 Ohm can be made with 2x 220 Ohm resistors in parallel, which makes a 110 Ohm resistor, again close enough.
I was still experimenting with various resistor combos when the images with the DMM readings were taken, so they are not the actual final values. :-)
For the inexperienced but curious as to why not just get the exact value, this page: http://www.radio-electronics.com/info/data/resistor/resistor_standard_values.php gives an explanation, as well as a chart showing the basic values of 3 standard series of resistors you will commonly find. It is possible to get much closer to the exact value you might need, but such resistors will be much more expensive, and not commonly found in boards/etc. that you might have available for recycling into this project.
Front marker/signals are 8 high, which splits nicely into two 4-LED wiring strings.
Rear marker/signals are two colums of 6 high on the rear, split into 3 parallel 4-LED wiring strings, and a single row of 4 on each side, split into 4-LED wiring strings.
Taillight is a single row of 8, split into 4-LED strings.
Brakelight was planned to be another of the same, but was skipped when I ran across a "3rd light" premade LED bar in a thorougly wrecked car in a junkyard that saved me the extra wiring work. :-) It's made of 9 very bright red LEDs inside, though not the same shape as LumiLEDs.
The front markers/signals are amber LEDs.
The rear-facing signals are amber, while the rear side-facing markers are red.
I recommend that color pattern for yours, even if you use different amounts of LEDs, as they are the same as on most modern vehicles I see on the road.
Because of the super-special sale price, I did not have a choice in lens styles for the amber LEDs, I got standard 90� ones, meaning that the light should be about evenly visible for a 90� cone centered on the lens. For the red LEDs, I ordered from a different company to get real LumiLEDs, and they have a variety of lens shapes. I used and recommend the 60x120� lens shape, as this means they can be mounted so that there is about 60� of vertical viewability, which is more than enough, and 120� of horizontal viewability, and that makes the side-visiblity of the taillight and brake light much better. I recommend using that lens shape for *all* the LEDs you get.
Since I both wanted to save weight and money, I did not use PCBs or even perfboard to mount the LEDs on, but rather just placed them for alignment in their respective sets on a piece of perfboard so that each LED in a set abutted the adjoining ones as evenly as possible. If you choose to get the non-spherical lens types, you need to make sure that you mount or glue these together so that the long axis of the lenses (obvious when you're holding them) is going to end up parallel to the ground. You also need to make sure the polarity of the LEDs is the same in each string. There is a bevelled edge on one corner; as long as that is the same on each LED in the string it is fine, since you'll be hand wiring them together later, so overall polarity is not important, just within the string.
Once you're sure they are all in the same direction, then VERY carefully place a single tiny drop of cyanoacrylate glue at the outer edge of each pair of adjoining LEDs, taking great care that none of it ends up on the surface of the LEDs, especially the lenses, and that it does not get on the leads or the perfboard.
I recommend using a red marker to dot the ends of your red modules in a non-lens spot as you are placing the LEDs on the perfboard, as the LumiLEDs are all completely clear casings, and you cannot distinguish them unless they are lit up. :-)
I chose to let mine sit for a day before any handling. Gently pushing the perfboard downward on a flat surface pushes the LED sets out of the board.
Wiring them requires some careful use of the soldering iron, as you only want to place enough solder to make a solid electrical connection and keep the wire from falling off from vibration, without heating the LED very much (too much heat will damage them). If you haven't ever soldered anything before, practice on extra wire or old parts or recycled boards first, before you attempt the LEDs, unless you happen to have enough money for ordering spares. :-) I won't go into good soldering practice, as there are a lot of places with good tutorials for this. Just remember that practice makes perfect.
To wire them, I just cut 1/2" of wire off of a bunch of unused resistors I had around, including those I would be using in this project. That's enough wire to go between each LED in a string and wrap in a J or U bend around the leads on either end, to crimp snugly to the LEDs lead with your needlenose to hold it prior to soldering. Also place a length of wire on each end lead of the string, black for the negative (cathode) end, and red for positive (anode) end, just so it's easier to remember and wire up later. How long the wire needs to be depends on your casing and how many strings you are putting in parallel in each spot. It should be at least long enough to reach across the entire length of the casing inside, plus an inch or two for oopses.
Do all the wiring before you solder. You can then test your string with your light's chosen power source and the appropriate current limiting resistor you calculated previously. If the string lights up, you're ok to solder. If it doesn't, you need to first check your connections, to make sure they're not loose--if they don't conduct power without the solder, they're not good enough connections. Don't depend on the solder to do anything more than ensure the joint doesn't come apart. :-) If the connections are good, then make sure your LEDs are actually in the correct polarity. If you find one that isn't, you can either break the string apart, reposition it, and reglue it, or you can wire to that one in the opposite direction (which will probably take longer wires).
After all the intra-string wiring is done and tested ok, solder the wires in place.
Now that white paint comes into play. Very carefully, paint the rear and side surfaces of the LEDs, ensuring you don't get any on the front side at all. Let it dry, then recoat it at least twice more, drying thoroughly each time. What this does is help reflect (diffusely) all that otherwise wasted light that would be shining back inside your casings, and instead let it be seen by others, making you just that much more visible--this ends up increasing the surface area that is actually illuminated from just the lens area to the entire surface of the LED (albeit much dimmer than the rest of it). Once it's dry, test the LED string again. If you see a lot of light shining thru the paint, you'll need to recoat it until the minimum light shines thru a reasonably small thickness of paint--you don't want to glob it on, either. For me, 3 coats was enough to call it good, but I could have probably used at least one or two more to make it better.
Step 4: Flasher Unit
The venerable 555 timer in "astable mode" is all I would use here. There are some good tutorial pages with lots of examples of how to use this chip, with these three at the top of a google search for "555 circuits":
The old Forrest Mims III books are great resources for a lot of things you can do with them, too.
If you want a different rate than I used, just look at those pages and there is all the info you need to set it up any way you like. :-) You can also use transistor or other types of clock circuitries, but the 555 is probably the easiest to use for this kind of thing, especially as it has many varieties tailored to specific uses, including very low power versions. I do recommend that however you do this part, you use high resistor and low capacitor values, so as little power is used up by the flasher as possible, as most variations of this will end up running the entire time the lights are on.
I actually didn't use a 555 in the existing system just because I already had the 12v electronic flasher unit from the scooter carcass, and minus it's large plastic casing the board inside easily fit in a small space inside the front headlight unit. But when I build a new set for the recumbent-in-progress, I'll be using the 555 or something similar. Part of the reason I did use the existing flasher was because it only uses power while signalling is happening.
Since the LEDs would take a lot more current in total than the 555 can directly supply, it doesn't do the job of flashing the LEDs. Instead, I used simple transistor circuits to do that job, and since I had a bag of NPN 2N2222's with metal cases laying around, I used those since they'll dissipate a lot more heat before dying than the common plastic cases would, even without a heatsink. Since they are only passing current for the time I'm signalling, and actually only half of that time with the 50% duty cycle of the signal coming from the 555, they serve well enough, although the ones on the front signals get pretty hot during signalling. I've left them on for testing before use for an hour, and nothing failed, even though I'm exceeding the power dissipation specs for the transistors for the front signals. If you have no parts laying around, I recommend getting something with a higher power rating, but nothing massive or heatsinky is required, unless you parallel a lot of LED strings together thru these things.
Both of the signal paths are designed to only pass power thru the transistor during signalling, to minimize the wasted power across the transistor.
The rear signal simply shunts the power away from the side marker and into the rear signal LEDs. The 4x 3-LED strings are wired from power to the collector of the transistor. The 1x 4-LED side marker strings are wired from power to emitter of the transistor. The emitter of the transistor is wired to the current limiting resistor set, which is used for *both* of the LED string sets, just never at the same time. The current limiting resistor is chosen for the shorter strings, so the LEDs aren't burned out, which for mine is 110 ohms for 3 LEDs. Since the 4-LED strings need about half that, they're only going to have about 35 mA thru them, which means they will not be nearly as bright as they could be. Since they are the red rear side markers, and I *also* have the red rear taillight with wide-angle lenses, I was not that worried about it.
What happens is that when you switch the 555 timer pulses with the left-centeroff-right switch so they go to one of the turn signals, they turn on the transistor which allows current to pass thru the shorter rear signal strings. Because those have a lower voltage drop even including the transistor's small (0.7v) drop than the 4-LED strings, the power is robbed from the red side markers which then go so dim as to be virtually off. The rear-facing amber 3-LED sets on that side now get all the current, so they light up, until the signal to the transistor turns off as the 555 pulses continue cycling.
That makes the rear-facing signals VERY obvious, from the side or the rear, and most importantly twice as obvious from the vehicle behind you in the next lane to your left or right, where it's most important that that vehicle be aware of your intentions and presence. Just remember that even though this makes you really visible and your intentions clear, it doesn't mean the vehicle will yield to you, so you still have to be sure you really have a place to go before you start changing lanes, etc. :-)
The front signal shunts the power completely away from the marker, and into just itself, because I chose not to use a second front-facing signal set due to insufficient parts. I recommend using the rear signal method for both front and rear, instead of the method I actually used.
For these front signals, it just greatly dims the marker on that side, so there is a blinking without total loss of light on that quadrant to indicate your presence. It's not as obvious a signal as the rear method, but it's also less important, as you are facing that direction and can much easier see conditions there instantly and react to them.
Because they aren't easily just glued together, and they get hot, all the transistors and current limiting resistors *are* mounted on perfboard and wired up there. A PCB would be easy to do, too, if you feel like it, but I never drew one up--it's too simple to wire to worry about for me. :-) There is one piece of perfboard in the front module and one in the rear module, each containing all the transistor/resistor parts for both side's electronics, so two of each.
If you used identical front and rear signals (except for colors, having all amber in front), you'd be able to use a single board in just the front module and save some parts.
You can use many other methods of switching the power to the lighting sets, but most of them are going to waste power across a transistor when it's not necessary, and this circuit only does it when it *has* to, for the shortest amount of time possible to do it's job.
I used silicone to attach the perfboard to the inside of the casing after wiring it to the LED sets.
Step 5: Taillight and Brake, and Brake Switch.
The brake light is an additional set of LEDs wired the same, except that it does not directly connect to power--first it goes thru the brake switch.
The brake switch can be done in several ways. The easiest is to buy a brake lever with integrated switch, but most of them are very cheap, plastic handle and all, and the momentary switch inside is not sealed against anything, almost exactly the same switch you'd find inside your computer under the reset button. I used one of these at first, but it didn't work when wet, and the handle lever flexes a lot when squeezing the brake hard, like it's going to come off in my hand or something. Ugh.
So you can instead use a magnet and a reed switch. Reed switches are really neat, in that they're completely sealed against weather by their nature, and simply close (or open, depending on type) whenever you get a strong enough magnet close enough to them. Most of the security systems in homes use these on doors and windows in easy-to-mount plastic boxes with either screw terminals or wired tails, so you can order them online if you don't have any around. A bare reed switch can also be used, but they're fragile and you'll have to mount them carefully so the leaves of the reed inside are at the right angle and rotation to be affected properly by your magnet. Either way, it's important to get the right kind. What you need is the Normally-Closed (NC) type, meaning when there is no magnet nearby, it is closed, or shorting across (on).
I actually used a bare reed out of a really old calculator keypad I'd gotten in a junkbox many years ago. Silicone sealant was used to secure it to the bottom of the hinged area of the brake lever mounting, parallel to the edge. I soldered it into the power path for the brake light at this point, after the silicone cured (overnight) Then I experimented with magnets I had laying around to find one that was very small and would trigger the switch open only as long as I was not pulling the brake lever *at all*. I found that one off the back of a name badge worked perfectly, and glued it on the bottom of the brake lever itself, at it's base by the hinge point, so that it was where it would keep the switch open unless the brake lever is pulled a little. I have it set so that I can pull the lever a tiny bit to engage the brake light without actually engaging my brakes, so I can *indicate* a stop without actually slowing down first, to warn bumper-huggers behind me that they're about to run me over without forcing them to actually do so. :-)
I would recommend using the enclosed type, as they're less fragile, though. I already broke two of them as the bike's fallen, and while not difficult to replace, it's annoying. The enclosed ones wouldn't have been damaged.
If you intend on using higher-tech controls for all the LEDs, so they are dimmable, etc, you can instead use a Hall Effect sensor in place of the reed switch, and that'll be nigh invulnerable. ;-) But you can't pass power *through* a hall sensor, so you would need to run that signal to the dimmer for the brake light instead. Or have it brighten the taillight, which could have all the LEDs wired up to it for both tail and brake, just running at 1/2 brightness until braking occurs. Either one doubles the brightness for you, indicating braking pretty clearly. Your choice. :-)
The only thing you really have to modify about the taillight casing itself is to remove the plex diffuser (if any) and the lighting module and inverter, since you will not use those here. If you prefer, you can use something else to house the taillights, such as a project box or almost anything you can seal to be weather resistant. You may still want some type of diffuser for the LEDs, simply so they have the biggest apparent surface area possible, which makes you more visible than a very small very bright point of light.
I used old cottage cheese container lids, because they're translucent and flexible. Unfortunately they're also impossible to glue, since I found nothing that really sticks to the type of plastic they use for this. SIlicone worked the best, but it will still peel off. Still, they've stayed sealed up well enough for several months of daily riding now, and since the bike is my only transportation, everything on it gets a good workout. :-)
The images show some of the stages of construction, and images to compare the lit and unlit states with. All of the lit images where the LEDs don't appear bright are ones where the flash was used. The ones where all you can see are the LEDs were taken with no flash in an unlit room. The very last image shows the lights with the brakelight module zip tied on top, both zip tied to my bike baskets, below one of my old unsuccessful motorization attempts.
Step 6: Mounting Everything to the Bike
Mounting the headlight is easier, as many bikes already have a place for clamping a reflector to, which you can replace with this unit if you wish (you might still need the reflector depending on local laws). I recommend putting the headlight where it will pivot with steering, so it can light your new direction as much as the one you're already going in. It's a very wide angle light, so it doesn't matter that much, as more of it's purpose is to help you *be* seen than to see. But it does light up a lot more of the close-in road than any regular bike light would, much more like a car headlight does. You should still use a long-distance spot-style headlight , preferably one mounted on your helmet, so you can look around at street signs, around corners you're about to pass, etc, and point directly at vehicles coming your way from side streets ahead to let them know you are there, in case they don't notice your very bright side marker lights and regular headlight. :-)
I used a mount for an old generator-powered metal headlight, of which I only had the nice mount and the rusted casing of the old headlight in a junk bin. The mount clamps around the handlebars and then has a pivot pont I just bolted into the top edge of the headlight module. There are many possible ways to mount it depending on the hardware you have around.
For many cases, using radiator hose clamps may be a really effective option, for a less permanent mounting you could just use good zip ties, but I can tell you from experience that they can break during a ride after enough sun exposure to dry out the plastic, especially if you hit really big bumps.
Wiring it all together is really the last step. The cables you need to run are the ones from the brake handle switch to the brake light and power, from the turn signal switch on the bars to the front unit, and from power to each unit front and rear, and the turn signal from the front unit to the rear one.
I recommend running the power only to the front unit from the battery, even if you switch it on and off at the battery instead of the front unit. Then run power from the front unit back to the rear one, but this depends on where your battery is. Mine are in the middle of the bike.
To hook all the front stuff to the back module, I'd use a multi-wire cable. Since none of this stuff takes much power, you can use old ethernet cabling or an old parallel cable. If you want, you can actually install connectors to mate with them (recommended), or you can just wire the cable directly into the modules. It needs to have at least 5 wires, for power, ground, the brake power, left, and right.
Run the brake switch to the front unit. From there, hook one wire to power, and the other will go to the wire bundle, and thence to the rear module's brake LED set(s).
Run the turn signal switch to the front unit, and connect it's common wire to the flasher circuit. The left wire will then go to the transistor base pins for the left side LEDs in front, and to the wire bundle, to go to the transistor base pins for the left side LEDs in the rear. Same for the right wire, to the right side base pins.
The headlight goes right to power and ground, so it's always on if the lights are on at all. Same for the taillight, via the wire bundle.
If you are going to have your charger charge the batteries while connected to the bike, make sure that you are not powering the lights while it charges, because the chargers often put out significantly more voltage than you have allowed for in the current limiting resistors for the LEDs, and that could damage or destroy them. Best is to use a jack (like headphone jacks and some DC input jacks) that cut off one signal (in this case, power to the devices) while the jplug is inserted. The one I used off the lawn trimmer doesn't do that, so I have to be careful until one day I get around to actually doing it that way. :-)