Potentiometer with boost circuit?

[flashlite]

I want to build a lantern that runs on two C or D batteries and has 4 to 8 white LEDs. I'm obviously going to need a boost circuit to drive the LEDs on only two cells. I also want to use a potentiometer so that I can dim the lantern. I don't know much about electronics but I'm thinking there could be a problem with having a boost circuit and a potentiometer together. I was thinking of ripping the guts out of a Dorcy 2AA or 2C flashlight to get the boost circuit and the LEDs that I'll need. Will this work? If not, what are my options for building a lantern like this?

 

[Lynx_Arc]

It should work, there are threads where it lists a resistor on the dorcy circuit for the 1AAA version you could try putting a variable resistor in place of it in the same general range or put one before the boost circuit to drop the voltage before it gets to the boost circuit. A quick way of testing this theory is take the end cap off a light with batteries in it.... and use the potentiometer to connect the negative of the battery to the case. This should give you an idea what will work in that fashion.

If you didn't mind less runtime a 4AA lantern resistored is a lot easier mod and 8 LEDs driven at 20-30ma should run for perhaps 12-20 hours or so off of AAs, also you can use nimh AAs in it if you desire to later.

 

[MrMimizu]

You can also get a fatman at www.taskled.com
It's a boost circuit which is already designed to take an external pot for variable brightness control.
georges80 is also a CPF member and is great answering questions.

 

[andrewwynn]

i second the fatman... and second the comment about george.

-awr