Hi Floyd, you talking about something similar to this..?
My lamp is pretty simple really, standard LDR along with a custom driver sends a PWM signal direct to a separate (modified chinese) driver board, whereby I can choose between my constant feedback or normal light output. This works to a degree but I think LDR's are the limiting factor here with light sensitivity. I have tested mine for nearly two years with another member of the DCC and they have proved that the concept works, and certainly my design is very reliable. I echo the concerns above about sudden beam drop but I have never really found this a problem, It would be fairly easy to counter this.
To give you a heads up though, one thing you need to bear in mind is that cave walls generally have very poor reflectivity, so this will limit the practical claim of saving energy, although it certainly does work very well when you are on all fours, and it is really nice to see no change of percieved light as you move your head from a close wall to walls or objects that are slightly further away, of course the light is adjusting all this time! Annoyingly fine water vapour affects output, as can sweaping your head across ropes or other objects.
There are other problems that I could not address in the design using an Oldham headset above, which I am reluctant to divulge (I have spent some time thinking about this and having been thinking about a solution!!!), this means I will need to design a slightly different way of housing the sensor and light assembly. Something I was hoping to do on my apprenticeship starting this year!
It is funny but I originally designed mine as an automatic beam dimmer as I help the DCC give tours at Alderley Edge, thought it would be good to not have to manually dim the lamp every time I spoke to members of the public! Of course they generally point their lamps at your face so it did not work for its originally intended application so well, but for increasing battery time in squalid caves, yes, for more open spaces (i.e. anything bigger than a small room) it does very little if anything!
I like your idea of RGB / light quality intervention but I doubt it will work. I suspect the reason a flame gives a more natural '3-dimensional' look to a cave is that it constantly flickers and moves, hence shadows move (more often than not by a greater amount than the movement of the flame, dependent on distances involved between light source, object casting shadow and where the shadow lies) independently of your field of view, and this gives your brain more 'information' to enable you to better perceive a 3-d environment.
Anyway, I hope you find solutions to all the little niggles you will come across, I think persuading the caving community they need such a lamp will be your biggest hurdle but I am sure there will be plenty of good folk out there who are willing to test a working prototype out!
I wish you luck and hope the project sees great success
PM me if you want to chat.
Olly.
