- MR-16 (~50mm) 20W 12V Halogen globe (sealed front): from
- Halogen globe holder: from Jaycar
- Switch: from Jaycar ~$1 each
- 50mm PVC pipe: from hardware shop ~$a couple
- 50mm PVC pip endcap: from hardware shop ~$3
- Hose clamps: From servo/auto shop/hardware ~$3
- Assorted odds and sods: from home $0
"Why make a new version if V2 worked well", I hear you ask? Because it's
there!... Hmm no wait... 42! .... Nope, still not right.. Ahhh! Because it's
This version is similar to the main beam from my
Version 2 lights, but uses 50mm PVC conduit for the housing. This is
the stuff that is lying around every building site, used for plumbing. You
only need about 10cm for the actual light, so you can probably find some
lying around. If not it'll only cost you a few dollars at the local hardware
shop. To seal the back I used a standard press fit cap, which was about
There are two ways to go about construction - build the housing, then
do the wiring (which I did), or wire it up, then build the housing (which
is probably easier). The first way has the advantage that you know what
you're doing, and it's easier to paint the housing if you want to make it
look flashier. The second way means you're not trying to solder joints in
the bottom of a 50mm diameter cup.
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...
Since the endcap provides a flat surface I moved the switch to the back
of the light. This looked pretty plain, so to provide a low-tech on-off
indicator I drilled a hole and put an old red miniature light cover in it.
Light coming through the reflector of the bulb shines out through this,
and it works disturbingly well
The internal wiring is almost identical to the
Version 2 . The wires come in, get tied in a knot to provide stress
relief, then one goes to the switch while the other goes to the bulb. Another
wire betwen the other switch contact and the other bulb contact completes
the circuit. You could use a variety of methods to attach the wires but
I'm happy with the cheap solution of solder. A standard RCA plug provides
a quick release method of attaching the light to a battery, and comes undone
easily in a crash.
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...
To lock the bulb in I used a similar method to the lock ring in
Version 2 , but an advantage of PVC piping is that a 5mm section of
conduit makes a great lockring. Just cut about 1cm out of it and it should
fit into the main housing. Use a bit of adhesive to lock it in place, and
put a few screws around the outside to lock the bulb in place. Assuming
you've put it all together OK, you should be ready to attach the lights
to your bike.
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
A problem with PVC is that it's a pretty boring white, with weird bits
of text on it. Granted these lights are always going to look a bit industrial
compared to commercial systems, but they don't have to look that ugly. If
you've got some paint lying around home give the housing a quick going over
with sandpaper, then wack on a few coats. Light colours such as yellow take
a few coats to mask any marks on the housing. In cold temperatures (under
about 15 Celcius) most water based paints will be very slow to dry. Either
use an oil based paint, paint in a heated room or similar, or use the heat
from the light itself; Hook up the battery, put it on trickle charge, then
turn the light on. Just be careful not to start a fire - I'm guessing some
paints could potentially ignite.
It's also really easy to adapt this design for smaller MR-11 globes, like the 10w one described in my Version 2 lights . The only trouble is finding appropriate sized PVC pipe - try a few different places, and remember it's easy to make a lock ring to make the internal diameter a few mm smaller. Currently something like this is my main bar light, since it lets me run a smaller battery for a given run time.
I'll get some piccies up soon!
Previous: Version 2
Next: Version 4
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