Hi - I'm trying to set up a number of low-power (<=1mW) visible laser beams, running continuously for hours at a time. I started with cheap ($AU10) laser pointers, which worked fine off batteries, but replacing the batteries was a pain. So I hooked up a 4.5V supply to them.. ...Bzzp. Thank you for playing. Seven dead laser pointers later (and some frustrating hours thinking "but I'm sure that's 4.5V.. why is that so dim? why wasn't it dim before?"), I'm looking for a better solution. From googling and reading old threads here, I gather that I need to build a current regulator using the built-in photodiode, for every single laser. This looks fairly involved. So how do off-the-shelf laser pointers survive without them? Is it something to do with limited maximum current from small batteries? This URL [ http://www1.jaycar.com.au/productView.asp?ID=ST3115 ] seems to be selling just the diode, and saying "just hook up a battery and you're good to go". How's that work? I don't need a lot of brightness (just enough to trigger an LDR), so running the diodes at way under their max output would be fine. Is there a simple way to keep them shining without eventually killing them? Thanks, Gwyn.