Re: convert 12V down to 9V DC

On Oct 3, 2:29 pm, mrdarr...@xxxxxxxxx wrote:
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-Equati...

Thanks,

Michael



Update - surge current is around 15-20 A actually with the 12V
battery. A linear regulator might not be such a great idea after
all...

Michael
.

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