Please recommend . . . .

[islw2863]

I want to build a very small switching regulator circuit that will :

accept voltage in from ~2v to 6v
output 6v and 1 to 2 amps

this is intended to solve the annoying problem that a flashlight gets steadily dimmer from the moment you turn it on with fresh batteries until you can no longer tolerate its yellow and dim color and toss/replace the batteries. This circuit would maintain the same brightness until the batteries suddenly die. Many LED flashlights already use such circuits. I would like to provide such a circuit for my 4 cell incandescent bulb Maglite. The circuits used by the LED flashlights won't (I think ?) work for an incandescent flashlight. I have scoured the internet already searching for a circuit that is very small with low parts count so it can fit inside my Maglite to no avail.

If you know of good small design that would accomplish please steer me in that direction. Thanks

[audioguru]

Hi Islw,
Welcome to our forum.
Boost-buck voltage regulator circuits are available that the LED flashlight makers use. Their circuits are very small because they don't have the massive current of your incandescent lightbulb.The lighbulb wastes about 90% of its input power as heat instead of light.
If a small boost-buck regulator could be made to supply enough current for your incandescent bulb, it would maintain the same brightness until the batteries suddenly die, just like you said. Which is about the same operation as Ni-Cad or Ni-MH rechargeable battery cells. Have you tried them?

Ni-Cads and Ni-MH's have their own problems:
1) It is hard to find D cells that don't have just a little low-capacity AA cell inside.
2) They must be used frequently to be useful since they self-discharge in a month or two.
3) Their average but very stable voltage is only 1.2V each, instead of 1.5V like disposable cells. But don't forget that the voltage of disposable cells drops sharply and much lower throughout their life.

A complicated and maybe impossible power supply, or a rechargeable battery?