My electricity went out recently. I have lots of flashlights, but I came to realize I ought to have a lantern-type light.
In my darkroom I have a red Cree screwed onto a CPU heatsink using a LM317 as a current driver. Using a 5v wall-wart this makes a great non-directional safe-light that lights up the whole room. I want to make something like this on the cheap with a white LED for emergency use.
Instead of using direct drive (low runtime) or a LM317 (inefficient) I would like to use a PWM driver circuit for more battery life and adjustable brightness. I would like "very low, runs forever" mode and a fairly bright mode. I could use a 6v lantern battery and a buck circuit, or use more-common AA batteries with a boost circuit. Maybe I could get a circuit that would work with practically any batteries, that way it would start boosting the battery voltage after it dropped below V_f? This sounds ideal to me but I don't know where to buy such things. I don't want to spend a lot either, or else I would just buy a ready-made lantern.
In my darkroom I have a red Cree screwed onto a CPU heatsink using a LM317 as a current driver. Using a 5v wall-wart this makes a great non-directional safe-light that lights up the whole room. I want to make something like this on the cheap with a white LED for emergency use.
Instead of using direct drive (low runtime) or a LM317 (inefficient) I would like to use a PWM driver circuit for more battery life and adjustable brightness. I would like "very low, runs forever" mode and a fairly bright mode. I could use a 6v lantern battery and a buck circuit, or use more-common AA batteries with a boost circuit. Maybe I could get a circuit that would work with practically any batteries, that way it would start boosting the battery voltage after it dropped below V_f? This sounds ideal to me but I don't know where to buy such things. I don't want to spend a lot either, or else I would just buy a ready-made lantern.
