Date: Sat, 23 Jun 2001 05:21:03
From: "neil barnes" <[EMAIL PROTECTED]>
Subject: Re: in car power supply
AAAAAAAAAAAAAARRRGGHHH!
Irrespective of whether or not it worked for John, this is a Bad Idea[tm].
The power supply in the libretto saves space and heat by moving the major
regulation off-board and into the mains adaptor. It's expecting 15.00v and
anything above that level *will* cause problems. The power supply in a
running car is less than clean - spikes of tens of volts are not uncommon
(though running it from a fully charged battery with the other electrical
systems (and of course the engine) off should be ok, if you can get it to
recognise the external power).
As an absolute minimum, use a shunt regulator consisting of a choke
(inductor) in line, a large capacitor across the rails, and a 15v zener
across the rails after a current limiting resistor. A slighly more
sophistcated design would use a low drop-out series regulator instead.
Calculation of the appropriate values is left as an exercise for the student
- assume it needs to supply a peak current of 2A at 15v.
(you didn't think I was going to risk getting shouted at when you break your
lib using my values, did you? :)
The prefered option is to use a DC-DC converter which contains within itself
the necessary chopper, feedback, rectification, and regulation circuits -
imagine using a dc-110 and 110-dc without the 110v bit. I don't know about
the US market, but I've seen these available in the UK. If you can't find a
15v unit, you can use a 12v output unit - these are much more common - with
the kicker circuit from Xin's page.
Sorry to harp on - but like Pres said, if it's worked, you've been lucky.
And replacing your lib is now no longer as easy as going to the shop and
buying a new one.
Neil
>From: "Shepardson, John D." <[EMAIL PROTECTED]>
>Reply-To: Libretto <[EMAIL PROTECTED]>
>To: Libretto <[EMAIL PROTECTED]>
>Subject: in car power supply
>Date: Fri, 22 Jun 2001 09:20:05 -0700
>
>Date: Fri, 22 Jun 2001 09:16:24 -0700
>From: "Shepardson, John D." <[EMAIL PROTECTED]>
>Subject: in car power supply
>
> > I am looking to power my lib50 in my car. I have been using a rather
>bulky
> > 12v-110v converter. my question is ....is there another way. maybe a
>smaller
> > less plug involved method?
>
> > Paul D. J. Davila
>
>Sure there is another way. Take a pocket knife and cut the power cord
>where
>it enters your Lib and hard wire it into your car's dc electrical system.
>
>Works great, I have had mine attached for 3 years and 50,000 miles.
>
>John Shepardson
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