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Subject: Re: [ battery faq]

Re: [ battery faq]

From: Uwe Freese <>
Date: Sun, 8 Sep 2002 16:03:33 +0200

Hello Björn,

Björn Stenberg wrote on Sunday, September 8, 2002, 3:05:52 PM:

BS> > A good circuit for powering from a car battery or other source
BS> with a higher voltage would be a 600 mA fuse and a 9V regulator like
BS> a 7809 of your favourite manufacturer in series.

BS> it's that if u use just a 7809 the voltage is about 8 volts, I
BS> experienced it 2 times (1 a while ago but I remembered when the 2nd
BS> spit out just 8 volts)

BS> the 7809 needs a lil buffering the energy, I made this witch adding a
BS> 470uf/25V condensator to input and output

I think the problem is that one should use a low drop voltage regulator.
A standard one needs 2-3 volts more input than output voltage. And maybe
his car battery had less than 12 volts.

But it is useful to have something like a 470uf/25V connected in any

Bye, Uwe.
Received on 2002-09-08

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