I'll show you PWM in action, it's a constant 5v, what you vary is the overall current the 555 will chop up the load giving the LED a break and you use less current, 555's not going to be that efficient.I was testing this cheapy oscilloscope i bought off of ebay so i tried it with PWM (which can be done with a 555 or an Arduino)http://www.youtube.com/watch?v=hLSzo9F4qbo
I was watching a video at adafruit discussing a 4-AA battery pack for charging an iphone. Bottom line - you can only get 500mA from AA battery.
I've spent a while with google, deal extreme, and aliexpress, but if you can point me in the right direction it would be helpful.
The prebuilt step-up LED drivers on Deal Extreme won't work? Have you tried FastTech or intl-outdoor? I know they have a few 1 or 2 AA 1W LED drivers which use the PAM2803 IC. If you're in the US, I can give you a link a to US vendor that stocks them.
I took a look at the datasheet, PAM2803 based modules could be good. Maybe that's what a lot of these modules use, they seem cheap enough. I'm located in Canada.
Excellent question. Deal Extreme has a bunch of items like http://dx.com/p/1-5v-350-400ma-constant-current-led-driver-board-for-diy-flashlights-128096 which may well be exactly what I want, but the description is so poor I can't tell. "Voltage: 1.5V" do I just assume they mean input voltage and it outputs a higher voltage? Even if so, what is the maximum output voltage, the maximum input current, will an Alkaline AA even be able to power it? Does it have to be 1.5 volts, can I use 2 cells to lower the current needed? It really is frustrating. Maybe I should just order something that looks promising.I took a look at the datasheet, PAM2803 based modules could be good. Maybe that's what a lot of these modules use, they seem cheap enough. I'm located in Canada.