Jeez, looks like I might have opened Pandora's box. I wonder if TaskLED could reporduce this board again if there is enough of a demand...or if Charlie owns the rights to it. I haven't had a response back from him in a while - so who knows.
Ok, due to wintermute's post I've dug through my stash of parts and boards and have 17 freshly built boards. You can order either the 750 or 1000mA version - I'll put the final current setting resistor on prior to shipping (of course I test ALL driver boards).
Once the 17 are sold, that's it, I have no further PCB's to build more and it's not a driver I plan to continue building.
Now NOTE - at 1000mA output, for good efficiency and to minimize voltage drops (see below), you need to find a nice low Vf LED, preferably in the 3.2V range.
You Must also make sure that the resistance paths from the batteries, to through the case, nubbin, wiring, SWITCH, etc are all minimized. To push 1A through a 3.2V LED requires 3.2W at the output. Assuming 90% efficiency that means you have 3.2W/0.9 = 3.56W at the input. If you have 2 x NiMH cells at 1.2V each, you have 2.4V at the input. That means 3.56/2.4 = 1.5A at the input of the VIP driver. Even 0.2 ohms in the switch/contacts will be 1.5A x 0.2 = 0.3V of loss. That brings you battery voltage down to 2.1V into the VIP and the input current will now be 3.56/2.1 = 1.7A
You can see how critical it is to minimize resistance paths in a high current boost driver where you're only starting with 2 nimh cells.
You can find details of the driver and how to order one on my website - link in the signature.
cheers,
george.
