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[Viking <erthnsky AT bellsouth.net>]

I'm still a bit confused....just for clarity....
So the first step is deciding on how much AC voltage something uses and
then you backtrack to determine the size of the inverter needed?  Sorry
to be dense on this one.  Ron plugs his telescope into the cig lighter
of my truck, using my truck battery.  That's fine if we are at home, but
in some observing locations, we would need to park elsewhere, creating a
distance between the truck and scope.  I would like to have an
alternative power source that he could tote out with the scope and use
in the field.  It would also eliminate the number of potential cords I
trip on. :)  I saw this page:
http://www.mapug-astronomy.net/AstroDesigns/MAPUG/PowerBox.htm
But I'm not sure that he needs this much power even though he has an LX
200 with dew heaters.  I can find out how much power the scope uses, but
the dew heaters are homemade (Ron understands all this stuff-I don't)
and I have no idea, without asking him, how much power they use.  I also
have a old laptop with astronomy software loaded, and it would be nice
to use that in the field as well.  The laptop only works on AC right now
as it needs a battery, I think. I get confused when words like
resistance and amperage get thrown around.  I wanted to surprise him
with some type of portable inverter and battery operation, but I may
have to ask him.  I look online at various websites and just get more
confused.
On more homestead related topics, what uses around the farm would
something like this homemade power box be good for?  I like things that
can be used by more than one application.
Thanks for your patience, Don.

Bev


Don Bowen wrote:
> At 7/12/2006, you wrote:
>
> > Ah, Don, you're probably a good person to ask.... Can you please 
> > explain inverters?
>
>
> An inverter changes DC to AC.  Most often that is from 12 VDC to 120 
> VAC.  There are several types of inverters from motor generators to 
> solid state.  Modern solid state inverters are small and relatively 
> efficient.   They come in two flavors, modified sine wave and pure 
> sine wave.  The wave form of a modified sine wave is a step from 0 to
>  around 70 volts then a step to around 140 then back to 70 then 0
> then repeat the cycle to negative values.  Pure sine wave is just
> that, like comes from the grid though there may be noise on the line.
> Most applications do well with MSW but some printers and TVs do not
> like the noise.  Microwaves and other devices that depend on peak
> power do not work as well on MSW.
>
> I like several small inverters rather than one large one.  There is a
>  reduced overhead and I can tailor the loads as needed.  I nave 175, 
> 200, and 400 Watt inverters but the 175 is the most often used.  I 
> have recorded the wave forms and hope to get an article up one of 
> these days.

--
erthnsky AT bellsouth.net  BevanRon of EarthNSky Farm      NW Georgia USDA Zone 7
34.498N 85.076W