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This mod is provided by Leo W.
****** VersaBrix *******
After looking at Aragorn's Otterbox, I realized I wanted
to have a Versalux ULM (this is a 10-LED regulated module
made by Technology Associates) that was watertight AND something
I could turn on and off without having to compromise waterproofing
everytime I needed to do so. One option was to pot the Versalux
in transparent casting resin(the same stuff they use for those
'mummified insect' paperweights), but that still left the
problem of waterproofing the batteries and switching mechanism.
The switch was pretty easy - I just went for a magnetic switch,
one of those that you find triggering cheap window/door alarm
systems. The switch was available off-the-shelf at a local
DIY for under $3. This switch comes in 2 parts: the switch
and the magnet. The switch itself is normally open, and is
only closed when a magnet is held closeby(about 5mm or less),
completing the circuit and activating the light. Such a switch
was a logical choice to embed in resin as it required no mechanical
contact that might compromise watertightness.
The battery problem was a little tougher - if I used normal
batteries, the battery case itself would be the weak point
and very difficult to craft. If I totally encased the batteries
in resin, how would I change them? Taking the cue from some
clever cordless electric shavers, I opted to entomb two 1800mAH
AA NiMH rechargeables along with the LED module and switch,
with solid extensions (screws, in this case) wired to the
battery terminals, but sticking out of the resin, allowing
the batteries to be charged when the light was switched off.
I know, sealing the whole thing is risky because there's no
way for the hydrogen gas produced by the batteries as they
discharged to escape, but so far so good. In my next design
iteration, I'll probably incorporate a Gore-Tex vent - especially
if I choose to go with more batteries.
Since this was the first time I potted any circuit in my
life - I further decided to take the experiment another couple
of steps. The whole thing wasn't all potted at the same time
- I did the LED module first in 3 layers. Two of the bottom
layers appear slightly cloudy - that's because they were made
of resin mixed with a teeny bit of strontium aluminate glow
powder, giving a slight glow-in-the-dark effect which self-charges
every time the light is used. Before I poured on the 3rd layer,
I put in a blue tritium-filled glass-tube taken from a Traser
glowring. The 3rd resin layer was completely clear - no glow
powder used - leaving the LED heads and tritium tube fully
visible thru the resin. NOTE: Topping off the LEDs with resin
like I did completely neutralizes any effect the LEDs own
'lenses', resulting in a very diffuse light - if you intend
to try this on your own, leave the tops of the LEDs protuding
above the resin if you still want a 'beam'. The final step
was to embed all the above in one big cast, giving the result
you see below:
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This thing looks very cool when lit, like a block of ice. It's
also as solid and as heavy as one - no wonder they use this
resin to make paperweights! So much heat was produced by the
resin as it cured that it warped the plastic casting container
and discharged the NiMhs! The warped contained gave me a lumpy
result :P Overall, this light is very crude, but I consider
this a prototype - which, of course, must work! |
