Any of you who have read my previous posts, know I am a bit anal when it comes to side switches on lights.  I like them.....

With the availability of superb , state of the art, side switch drivers   from member Georges80, I am amazed that we do not see more lights utilizing his system.
George ( Website)  has over the years been quietly improving his excellent drivers. Today they incorporate a computer controlled UI (user interface) that is both simple, yet powerful and allows the end user to set and adjust  parameters  that are ‘fixed’ by other board makers. For example, the user 
can set and change at will the maximum current (ma) available to the LED,
( no more sense resistors) as well as setting the low voltage cut out point,
if re chargeable batteries will be used. Variable intensity, auto lock out, two different UI’s, plus many other features. Believe me, as far as drivers go today, these are ‘best of breed’.

I wanted to build a small keychain light. After seeing what fellow member   ‘tvodrd’ achieved, ( see above, picture courtesy of Bernie ) I got motivated and set about coming up with a design. Studying the body of  his ‘Larry Light’ it became obvious that the beauty is in the precision manufacture and quality control, along with  the fact that metal thickness has been kept to a minimum, thereby allowing a very compact and light weight package. 

I would have to select a very strong grade of aluminum to come close to his dimensions. The width will be determined by the driver diameter  and the length is going to be a little longer  due to the extra space required for the switch.  Also I had no idea if George would be keen on ‘miniaturizing’ one of his side switch drivers. Anyway I set the tentative design parameters at an outside diameter at ¾” and aimed for 2.25” in length.

I would need one of George’s drivers to be reduced in size to around 0.600”. I had two worries.  Could he do it and would he do it.  I think George became intrigued with the idea and rose to the occasion.
Many emails later, lots of experimenting and we had a finished driver measuring 0.590” with micro switch incorporated……… and the joint collaboration was under way.

 I thank George, for this project would not have been possible without his patience, input and unfaltering support.

Now I had the driver ‘sorted’, I set about the other items required.The body will be made from 7075 T6 Aluminum. Very strong,tough and hard.  And it will handle wall thicknesses of 0.025” and thinner without collapsing.    Just the material I need.

 
Moving back from the head, I selected a 16 mm ‘O’ ring set in the bezel. Resting against this is a UCL double coated glass window, custom ground to fit. Next a cut down McR18 reflector ( thanks Larry and Don for explaining how to do this correctly) resting firmly on a Lux III, epoxied to the heat sink in the middle section. Next is the custom, fully regulated, side switch driver set at 350 ma output. It has all the functioning features of it’s larger brothers. An amazing accomplishment in miniaturization. I can’t even see some of the components they are so small.

Battery power is a Cr2 primary cell, chosen for its size, good availability
and long run time at 350 ma. And lastly a gold plated spring keeps the battery in contact. My original design incorporated sealing ‘O’ rings but even with 32 TPI threads, there just was not enough wall thickness behind the threads of the battery tube for the groove, even for a tiny cross section ring.

A SS circlip in its own groove looks after attachment for a split ring and micro clip, and allows ‘end standing’ as well as complete removal if no attachment point is required.

 

How does it all come together. Well I am delighted with the overall finished light. The reflector puts out a center-weighted spot with more than adequate spill and quite frankly is 100% better than I expected. The overall length finished up at just over 2¼” with a diameter of ¾”. Weight is 23 grams, 37 with battery.

As I write this in late October 2006, Cree madness is upon us. And yes……an XR-E 
or the new Soeul P4  will fit, but the reflector and head would need  machining modifications.

 

                                                                 ‘Anglepoise’ Oct 2006