What electronics to get for this configuration?

[Bimmerboy]

Hi all,
I need to find the right driver that will allow me to run a TV1K LuxIII from a 6V alky lantern battery, and use a variable dimming pot preferably hooked up to the driver board itself although I'll be satisfied to hook it in elsewhere. This will be for a relatively low output mod with full regulation, running 400 to 450 ma at the most in the interest of lower heat and extended runtime. The reason for the TV1K is that I'd like to try a little toward the yellower end of the spectrum, hopefully without getting into green, and they're easily available right now.
Do I need a buck/boost converter? Buck for the initial full 6V coming from a fresh battery, and boost for when it gets very depleted and falls under the emitter's vf? Or will the battery be well spent before it gets down to the emitter's vf of 3.51V - 3.75V, therefore being better off with just buck? Please pardon my newbiness.
I've been looking at the Sandwich Shoppe and Georges80 stuff and just don't know what to get for this config. Hoping to get some suggestions before I start hounding the big fellas.
As always, you guys are great out there.

 

[Doug Owen]

[ QUOTE ]
Bimmerboy said:
Hi all,
I need to find the right driver that will allow me to run a TV1K LuxIII from a 6V alky lantern battery, and use a variable dimming pot preferably hooked up to the driver board itself although I'll be satisfied to hook it in elsewhere.

[/ QUOTE ]

Sure, the basic LDO regulator we've been using in the 'WorldTorch' should do nicely. You can see a photo of one of the prototypes here. This is the basic kit (available for $4 elsewhere on the site) modified with a higher current transistor. As I just posted on another forum, we just had some printed circuit boards made up for this circuit, currently being evaluated (pun intended). These should be available at a similar price (probably a few bucks more) fairly soon if you want to wait a bit, otherwise the DIY kit (or even locally purchased parts) and the instructions and information on the site will get you going.

Variable brightness can be approached several ways, but I chose (and recommend) steps via switch. Your eyes work 'funny', you need a large change in light to seem brighter. The linearity of a pot will not be satisfactory, although you're sure welcome to try (duplicating what I did...).

And yes, by the time alkalines get to .8 Volts per cell they are past use. A buck converter is useless. In this configuration (LDO linear, four alkaline cells, typical Vf LEDs) you'll get total efficiencies hard or impossible to beat. And cheap, too.

Doug Owen

 

[wasBlinded]

Georges80 Fatman board would work here wouldn't it? It supports potentiometer brightness control.