[AZ-Observing] Re: MSW inverters
- From: gene lucas <geneluca@xxxxxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Mon, 27 Oct 2008 22:39:50 -0700
Hi Dan,
That's a rather slick looking unit, with the solar power recharge
option... but Waaaaay overkill, haha!
WELLLL, for SOLAR observing.... SOLAR power... (?)
The little plug in unit I was referring to is like these models:
VEC1040A http://www.boatandrvaccessories.com/VEC1040A.htm
PI100AB http://www.boatandrvaccessories.com/PI100AB.htm
I have seen units like these on sale for under $10.00, such as at
Walgreen's and other places, probably Checker Auto or Pep Boys, ACE
Hardware ??
Poking around inside the one I got from ACE Hardware, I located the
variable resistor that evidently changes the frequency (I could hear the
"buzz" change pitch...)
However, I didn't plug in a clock and try it...
How to set an inverter to >>exactly<< 60Hz ??
Method 1: Run an AC clock for a few minutes and time the seconds hand
with a stop watch (or WWV...)
Method 2: Wire up one of the little neon indicator lamps (voltage
tester), with one wire tied to the hot lead from a wall outlet
(extension cord), and the other to the inverter output... The neon lamp
will pulse in time with the phase differences of the two AC voltages,
and go bright and dim as they "beat" against each other. When the
inverter "pitch" or frequency is tuned to match 60 Hz (same as the wall
current), the lamp pulses will slow down until the lamp stays out or
completely on for long periods.... I have an indicator like that on the
panel of my inverter, to "calibrate" it (without an expensive bench
instrument, like an oscilloscope). But remember that is 100 VAC you
will playing with, so exercise caution when handling the leads!!
Method 3: After setting it close, run your telescope and watch the sun
WITH APPROPRIATE FILTER!!! Or tweak the frequency to match sidereal rate...
Cheers,
Gene
(17250)
Dan Heim wrote:
> Gene,
>
> Yeah, I figured I'd be ok, but wanted to run the idea by the experts on this
> forum first. The unit I'm looking at is this one:
>
> http://www.boatandrvaccessories.com/852-2071.htm
>
> DFAC is going to be setting up for some public solar observing in Anthem
> after the Veterans Day parade, and I could haul along my extension cord like
> I usually do, but that's always a tripping hazard (especially at 100 feet
> plus and little kids running around). This unit is WAY more power than I
> need for the scope, but would be handy to have around for other purposes. I
> don't need this for astrophotography ... just visual, so I'm sure the
> tracking will be just fine. Thanks for the info!
>
> Dan Heim
>
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