convert 12V down to 9V DC

My kids' electric scooter has a 6V motor and battery. The 6V battery
doesn't give enough juice, but a 12V battery I installed gives too
much juice (wheels skidding when the pedal is pressed, etc).

The "Gas" pedal is a simple on/off switch.

I'd like to provide 9VDC, at about 5A (a guess - I haven't measured
the current yet - that will take some doing, to determine the startup
surge current with a kid sitting on it).

I was thinking LM317 with pass transistor (I've got a spare 2N3055),
but I'm wondering if I can simplify this schematic a bit (under High
Current Regulated Supply):
http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm

Why a 2N3904, why so many resistors? Can they be omitted?

I was also thinking of a buck converter, but I have no P-channel
mosfets.
http://www.daycounter.com/LabBook/BuckConverter/Buck-Converter-Equations.phtml

Thanks,

Michael


.

Relevant Pages

  • Re: Most awful hack job, but my kid likes it
    ... On the subject of kids and taking things apart, ... my son Henry helped put the battery ... compartment back but just watched me do the finicky stuff. ... was busy holding his other hand back and holding the safety glasses on ...
    (rec.crafts.metalworking)
  • Re: Stimulus Bill for Motorcycles
    ... young kids because there's lead in the battery and others parts of ... between 1990 and 2003 showing that over a million kids had been injured bad ... which also had a safety problem. ... equipment...or had proper supervision. ...
    (rec.motorcycles.harley)
  • Re: 11 year old girl attacks police.
    ... S Viemeister wrote: ... charges of battery ... Isn't it time you kids were in bed? ...
    (soc.culture.scottish)
  • Re: 11 year old girl attacks police.
    ... The Highlander wrote: ... charges of battery ... Isn't it time you kids were in bed? ...
    (soc.culture.scottish)
  • Re: night light for kids in tents
    ... relatively low intensity LED lantern thinking that battery usage would be ... What's wrong with a good ol fashion flashlight? ... Kids love flashlights at night. ... probably cheaper than qty: 1 LED lantern. ...
    (rec.outdoors.camping)