Version 4

Do you see the light?


  • MR-16 (~50mm) 20W 12V Halogen globe (sealed front): from Jaycar ~$5
  • Halogen globe holder: from Jaycar ~$3 each
  • Switch: from Jaycar ~$1 each
  • 50mm PVC pipe: from hardware shop ~$a couple /LI>
  • 50mm PVC pipe endcap: from hardware shop ~$3
  • 50mm PVC threaded joiner: from hardware shop ~$5
  • Hose clamps: From servo/auto shop/hardware ~$3
  • Assorted odds and sods: from home $0
The bits you'll need

Go Back Home or on to Helmet Mounted

I hadn't even finished Version 3 when new ideas were popping up. While getting a replacement PVC end cap after dropping a battery on the first one, I found a threaded joiner for PVC pipe. This actually came as two parts, a male and a female, both costing a couple of dollars each. I managed to resist buying this the first time, but a few days later I was back to get them. Bloody hardware shops close to work!

This joiner meant that for the first time I could have something vaguely professional looking. The threaded joiner could be used to clamp the bulb in place, and since the joiner and the end cap had the same outside diameter the annoying bump in the version 3 lights wouldn't be present.

I also found a switch in Jaycar that had an integrated 12V LED. It's reasonably obvious when the light is on, but it's kinda cool to have an on/off indicator. This switch also has the advantage that it uses a circular hole, which is much easier to make. Besides it was a gadget, and I'm a sucker for gadgets...

The switch

The first order of the day is to cut one of the joiner parts to remove any excess. I chopped the female part since that way I'd get a lock ring - the other way would look a bit weird. I think you can actually get these lock rings off the shelf, but the shop I was in didn't have them immediately apparent. It's not that hard with a hacksaw anyway. You may need to slice off a bit of the male thread to make the two parts fit snugly once you've got a bulb between them. Experiment before you cut, otherwise you'll need to visit the hardy again... I had to cut about 5mm off.

Once you've sliced up the lockring, you'll need to cut a few bits of the 50mm PVC pipe. You need a piece about 40mm long to join the end cap and the male section, as well as two bits about 5mm long each. These small rings then have about 15mm cut out of the circumference so that they will fit snugly inside the 50mm PVC pipe.

The inside of the light

Glue one of the small pieces into the lockring, so that it will actually hold an MR-16 bulb in place. Do the same for the male joiner piece, with the lockring right at the tip of the thread. You want the bulb to sit on the end of the thread, then be held in place by the lockring. This is where you don't want to find out if you've cut the right length off the male joiner - before you actually glue or cut anything try lining it all up!

Spacer in the main body     Lockring detail

To attach the various bits of PVC to each other, I used a plumber's adhesive specially designed for conduit. This is relatively cheap, but if you're really feeling like doing this cheap araldite or other common "glue anything" adhesives might work. Don't ask me, I'm a computer geek, not an industrial chemist! Oh oh, now I sound like a Trekkie...

Drill a hole in the end cap the right size for the switch. Fit the switch, then wire it up and solder. Note that the switch I used has to run from the positive terminal of the battery to Switch terminal 1, then from terminal 1 to the load, then back to terminal 2 on the other side of the load. The third terminal of the switch then connects to the negative terminal of the battery. This is required to have the LED glow when the switch is on. If you're just using a basic switch use the same wiring as Version 3

Since I wanted to paint the light, and it was the middle of winter, I put it together and wired it up. That way I could use the light itself as a heat source to dry the paint. If you can keep the lights in a warm environment you should be able to paint first, then wire it up.

Glue the end cap onto the 40mm piece of PVC pipe, then glue the male connector on so you've got a smooth tube of about 55mm diameter, with a screw thread at one end. Put a globe in the connector, tighten down the lockring, and your light should be ready for attachment

I throw my battery into a backpack, which helps keep it reasonably warm, improving performance. It's reasonably comfortable. You might prefer to bodge together some kind of bike mount - I've tried a bag in the main triangle of my old hardtail, but since it got replaced with a duallie there's now a spring in the way...

Probably the easiest way to mount your lights to your bike is to use a couple of hose clamps. Put a large one around the light, and wrap a smaller one through this. The smaller one then clamps on to your handlebar. So long as you're reasonably competent with a screwdriver (and why are you reading this if you're not?) it only takes a few minutes to mount or remove the light.

Of course, I had a clamp left over from my Version 2 lights , so a bolt through the side of the pipe and a little elbow grease resulted in a rather nice unit (if I do say so myself!).

The light, ready to go


Previous: Version 3
Next: Headlight Mk1

If you want to abuse me: lights@hired-goons.net