Current is like the flow out of a garden hose; When you attach a
sprinkler, the force of the water (voltage) and the resistance of the
sprinkler (hole size) work together to determine the current flow, but
water pressure (Voltage) alone doesn't determine the current. A short
circuit is like a hose with nothing on the end (all water just flows
through), open circuit is like having a closed valve on the end of the
hose. Current, Voltage, and Resistance (1/Conductance) work together
according to Ohm's Law, E = I * R (Voltage = Current times Resistance) -
that's the technical law for this.
I'd add, to what Tim said, that in a car electrical system there are
some NASTY electrical spikes & electronic noise pulses, ("Load Dumps"
when you turn the headlights on and off or the Air Conditioning starts
or stops are electronics killers! Car voltages can spike by a number of
volts, up OR down!) - so I'd not recommend just plugging a NetWinder in
without either some kind of filtering (an L-C filter at least!) and a
diode backwards across the leads (in case of reverse voltage spikes) -
or, better, a R-L-C filter with a Zener Diode across the output, to
limit the voltage to 13.5 volts or so - or better yet a well-designed
DC-DC Converter. Or even just use a small auxiliary battery with a
filter to the main car power, then run the NetWinder off that withj a
low-dropout regulator? I just don't think it's a good idea to put a
$700+ sensitive electronic device (price for the DM, 810 Mb HDD model)
straight onto car power with nothing to protect it from surges, myself
<G> It's YOUR computer though, do what suits you... You could also use
a 12VDC-to-117VAC inverter, then the power lump (Inverters are available
for as cheap as $25.)
I asked Corel for more info on automotive powering of the NetWinder
<G> I'll share what I hear.
Mark
Tim Gray wrote:
>
> the current draw on the netwinder is pulled not pushed? HUH?
> Oh well, as far as the other parts of the question....
>
> If the netwinder can survive a continous voltage of 14.5 to 15 volts then
> yes.. that is what your car's electrical system is at when driving.
>
> ----------
> > From: David Maslen <
>
> > To: Tim Gray <
>
> > Cc: wearhard <
>
> > Subject: Re: Corel NetWinder as a wearable?
> > Date: Friday, October 02, 1998 9:28 AM
> >
> > "Tim Gray" <> writes:
> >
> > > Actually you can draw 10 amps from your car's ciggerate lighter, but 5
> amps
> > > is a safer level of draw. I've ran a 1000 watt ac inverter out of a cig
> > > plug for 8 hours with a noticable rise in temperature but it didn't
> blow
> > > the fuse!
> >
> > Not being an electronic wiz, does that mean you could plug the
> > netwinder straight into it. Apparantly the netwinder is 10-12V 1.5
> > amp. The recent discussion on the mailing list said current is pulled
> > not pushed, so if the netwinder needs 1.5 is that all it will draw?
> >
> > ie. Plug it straight in?
> >
> > --
> > Binary Bar - Australia's first free access internet bar/cafe/gallery.
> > 243 Brunswick Street, Fitzroy, Melbourne, Australia. 3pm - 1am
> > http://www.binary.net.au/
>
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