There was a longer pause now ...
but not for doing nothing!
I added temerature control and overdischarge protection to 'testdevice 3' in the mean time. To get this all into the very smal casing I modified the circuitry: The rather big rotary switch able to carry the supply current must go and I replaced it by a tiny one for low level signals only. Also the mechanical arrangment had to be modified.
The result is below.
The AA cell is for size reference only.
The light distribution of this 'device_3a' is exactly the same as with 'testdevice_3' discussed at last in this thread - the optics are just indentical.
I handcrafted 10 samples of this headlamp for the cavers in our Austrian and German caving clubs.
Here you can see, which versions were produced:
http://www.bossert-inet.de/tobias/three_variants.pdf
and here you find the very detailed manual for it:
http://www.bossert-inet.de/tobias/usermanual.pdf
The samples were delivered in spring of this year - and must be recalled immediately after that, because of thermal problems. That's all corrected now and these devices are used now continuously under real caving conditions.
From this experience I learned, that a good headlamp needs an aluminium casing for cooling - not ABS as mine with an aluminium lid on the back side only.
I had contact to some European manufacturers of headlamps. Most of them told me, that the market for cave specific headlamps is too small to start such a rather complex development. For very low numbers of pieces it is not economical to use a proprietory casing developed for this device only.
One manufacturer asked me, whether I could modify the optical arrangement of the light sources to allow a standard rectangular aluminium casing. If so, he will develop the electronics and all other things needed and will offer such cave-proof headlamps commercially at a much lower price than common. Naturally with modern programmable digital switching, because rotary switches are too expensive and tend to be not really watertight.
That's it, what I'm developing at the moment ...
... and it seems to be feasible!
The fist prototypes achieve nearely the same light distribution as 'testdevice_3' - but all front windows lie in one plane, allowing a standard rectangular casing:
This demontration sample has no electronics inside, it has a six-pole cable so each led can be driven externally. As you can imagin by those scratches, it even was tested inside a cave. For this purpose I developed a (not so compact) box with electronic inside: No problem for demonstrating feasibility only.
Now I hope that this progression satisfies the needs of the manufacturers and one of them starts to develop an inexpensive headlamp optimized for huge caves on this basis.
