In reply to lithos: I was thinking of marketing them, but as I only charge about £20 each , and my eye sight is not what it used to be, I have made and sold 10 , but need to source sports type head bands that dont have a "nike" emblem on them.(dont want to get sued millions for making five quid)
I am also working on overcoming the problem that if 2 people are wearing one each, they will sense each other and one will turn off, as if it were daytime.
The leds are rated at 70 lumens, but I run them at about 50 lumens each, this gives a slightly lower light out put and does not heat up the led, therefore does not waste battery power.
I have to order some more components and make some more of the newer design circuit.
If you are interested I could email you the circuit diagram, it is very simple, I buy all my components off ebay.