To regulate or to buy a wierd battery, that is the question...

[Qbranch]

Hello all, q here. I'd like to enlist the help of the CD collective concious for a problem I'm having.

I find myself on a tractor pull team out here in Illinois. The rules stipulate that we can use as many 16hp briggs engines we want (provided we don't go over weight limit), and can use only one battery (there are many other rules of course but these two are pertinant).

Currently, our design has five engines. As you can guess, making a throttle cable system to pull all five throttles EXACTLY the same amount at the same time would be a lot of trouble... so I suggested using airplane servos to move each throttle individually.

Unfortunately, the 'only one battery' rule is the problem. Airplane servos run, maximum, 6v... and our starters and everything else runs 12v. With the number of servos I need to run... they can draw up to 4A@6V.

So here's my two questions:

A) Can anyone help me get started (or show me a design) on a regulator circuit that can provide the 6V@4A from a 12v dc source?

B) Do any of you know of a battery that provides both 12v and 6v? Something with a tap connected midway between the cells?

Thanks for any assistance,

-q