Click here for updates on MkII and MkIII of my light systems
Light.xls - This is a little excel application that calculates things like suggested fuse ratings and run-time for your intended lighting system. I take no responsibility for any death or injury caused by using this data.
If that link is broken, send email to happybaboon at hotmail dot com - don't use the feedback form on the index page - it's... urrr... unreliable.
It's now winter in New Zealand... The days are getting shorter, as the nights are getting longer. Because of my busy schedule, no longer will I be able to ride my beloved bike during the daytime... I need lights. A good 20W helmet/bar mounted lighting system will cost you up to ONE THOUSAND DOLLARS (NZ) - This obviously wasn't ever going to be suitable for my thrifty needs. I needed a bright-ass, long-lasting lighting system... I looked at some designs on the net (www.jeremyb.net has a good lighting system too!) and then came up with my own design for a light that can run an interchangeable 10W to 50W 12V 51mmÆ dichoric halogen or IRC halogen lamp with a ten to sixty degree beam angle. This light is seriously kickass... and can be constructed with minimal skills and equipment for less than $150!
What you'll need...
A battery
I settled on a 6.5aH sealed lead acid (SLA) gelcell. They retail for around $80, but you can sometimes pick them up cheaply from firms that are replacing the batteries in their uninterruptible power supplies. Gelcells are HEAVY - About 340g for every Amp Hour, compared to maybe 50g for one amp hour in a NiCad battery. I do think it is worth the weight however because - It's simple to use (you don’t have to build a battery pack) and they are built to be indestructible (good if it's on a bike) and can be used in any position.
UPDATED You can buy 7aH SLAs from Rexel New Zealand for only $22 +gst!!! This is an amazing bargain. Their lights are cheap too.
A bulb
The bulbs that this system uses are also quite expensive. A 50W dichloric halogen bulb with a 10° beam will cost about $12, a 20W dichloric bulb will be about $18. I recommend you use narrower beams (10° or less). Make sure you purchase CLOSED or SEALED bulbs. These have a piece of glass over the reflector and the bulb, which means that nothing can touch the bulb. It is important that if you do somehow touch the bulb, you clean it off with methylated spirits or electrical contact cleaner, using a cotton cloth - make sure that no fibres are left on the bulb by wiping it down with a clean tissue after the meths or contact cleaner has dried.
Plumbing Supplies
You'll need at least 15cm of 50mmÆ PVC piping. That should cost you about a dollar from Mitre 10 (no one else will sell you such a small amount).
You'll also need a standoff for the pipe, you don’t want the ones with the 10cm clearance (they'll make you look like a penis when you're wearing your light), you want the ones that are flush to the surface. These are really hard to find for some reason, but MasterTrade seem to have them most of the time. These will cost you about a dollar each.
You'll also need two push-on end caps for the PVC pipe. Again, these are available at MasterTrade; they should cost you about $6 each. If you buy two, you get a one-cent trade discount.
Switch
Any old rocker switch will do. But I use a rocker switch I got from Dick Smith Electronics for $3
Connectors Your SLA will have spade connectors on it, so you'll need some spade socket connectors (they are on the left in the picture). Some spade connectors (on the right) may also come in handy. I'm sorry about the low quality of this image. Prices for crimping plugs vary, but don't expect to pay more than about $7 for a package of 25 crimp lugs.
You'll also need some connectors to connect your helmet-lights cord to the power source. I use crimped lead connectors (kind of like banana plugs) as seen below. These are generally a little more expensive than spade connectors, maybe $8 for 25.
You'll also need a crimping tool, usually a multi-tool plier for about $10 - you'll usually find them with the crimping lugs.
Also pick up some epoxy glue - about $10 and some Velcro - Use the original stuff, it costs about $7 from Dick Smith Electronics and is mega-strong. Some cable ties that will go through the slotted vents in your helmet and around your top tube will also be useful (they are cheap-as too)
Cable
I used some tru-rip that I had sitting around, but I recommend light/medium duty automotive cabling from Dick Smith Electronics. It costs about $2 a meter. You'll need about four meters.
Various other things
If you don't feel like crimping everything, you could solder & heatshrink your cabling - this is a whole lot stronger and more conductive than crimping lugs. If you know how to solder and use heatshrink, chances are you've got access to it already. If you don't have the equipment already it's not worth bothering about, it'll cost you at least $50 for an iron, solder and heatshrink
Fan - I have a fan in my light, it was necessary because my 50W lamp was melting my PVC piping. 35W lamps should be ok without a fan, and 20W lamps don't need one at all. A 4cm muffin fan (what I use) will cost you about $20 at Dick Smith Electronics.
Once you have all your supplies, and all the other tools you might need... you're ready to start building your light!
Get the pipe sorted...
Cut the pipe so that it is between 10 and 15cm in length. Once this is achieved drill a hole in what will be the top of the light 30mm from the back (Hole A). Drill small (1mmÆ) vent holes around the front of the pipe, 35mm in from the end (Holes B). If you're going to ride in the rain, don't have too many on top.
The End Caps
One end cap needs to be drilled out so that the edges of the lamp can be glued in place inside the end cap. From the outside (front) of the end cap, there needs to be about 9mm of PVC. PVC end caps are thick, and are hard to drill. It takes a long time to get it right, DON'T RUSH or you'll likely screw it up. Test the bulb REGULARLY for fit Once you are satisfied with the fit, put a little epoxy resin around the inside lip of the end cap and mount the bulb - CAREFULLY - don't put the end cap bulb onto the PVC pipe until the glue is dried or you'll glue the end cap onto the pipe.
Drill a couple of vent holes in the other end cap to let the air out. Or put a fan in it like I did (difficult - don't try unless you're a soldering prodigy and patient).
The Cabling
Measure yourself and your bike for the specific cable lengths – DON’T GUESS
To wire the lamp, crimp a couple of the socket connectors over the two pins on the back of the bulb (these pins aren't really all that crimp-friendly, if you don't want to change the bulb around then I suggest soldering them fuckers down). Be careful not to crimp too hard, you might break the lamp.
You'll also need to crimp some cable into your new connection plugs. Strip the end of the cable (Don't use your teeth, it's bad for them) so that you have about 7mm of exposed core. Twist this in an anti-clockwise direction until it's solid enough to jam into the crimping lug, then crimp it HARD.
Run the cable back out through the hole in the PVC pipe and cut it at it's desired length (Measure from the top of the helmet to wherever you plan to attach the battery to your frame/person. Allow for movement!) At the end of this cable, crimp on two more lugs - Use the round lug that plugs into the round socket. If you have a fan, you'll need to crimp these so that they can be connected only one way round, otherwise you might get the polarity wrong and the fan won't work.
Connecting the battery and switch.
You'll need to use the spade socket crimp lugs on your SLA gelcell, and also to wire up most switches. There are so many ways to use this system (battery on your frame, in your hydration pack... switch hanging off your shoulder, on your bars...) that I'm not going to go into specifics here. Just make sure that you connect the battery to the lamp through the switch. If you need any help with this feel free to email me. (happybaboon at hotmail dot com)
Putting the lamp onto your helmet
For this you'll need the standoff, Velcro and cable ties. Trim the webbing on the standoff (by the screw holes) so that it conforms to the shape of the front of your helmet. Line the apex of the standoff with loop Velcro (the soft part) - cut the Velcro to shape and completely cover the top half of the inside apex of the standoff. Place your PVC light inside this and trace a line around it, so that the standoff won't cover the vent holes or hinder the movement of the bulb. Velcro this with hook Velcro.
Then, using the screw holes, attach the standoff to your helmet with some cable ties. Make sure the light is going to point straight and at an angle that suits you.
You may also want to Velcro the back of the PVC pipe to your helmet as well, and consider using a cable tie to ensure the cable from the lamp will fall off the back of the helmet and won't tangle around your arms, helmet or light.
Your finished helmet should look like this...
Now you can test your light...
This is my 20W bulb in action...
Here you see my brightly-illuminated pathway (kind of)…
This is the sort of light you get at a distance of 10-20m away from you with a 20W bulb
That’s looking straight at the bulb… Bright enough to fool the camera into taking the shot as a negative (freakin’ bright)
This is what it looks like from the side…
This is an even better head-on shot…
If you are still having trouble with this, or you're just a lazy bitch and would like to try to convince me to do all this crap for you (I don't mind, if I've got time) then email me at happybaboon at hotmail dot com.
