D.C. POWER CORD FOR ETX Last updated: 15 January 2009

Sent:	Tuesday, January 13, 2009 15:48:32
From:	Joel (earth-light@sbcglobal.net)
I just bought an inexpensive, good quality D.C. power cord for my ETX
125 which I thought might be of interest on your website. If you agree,
feel free to post it in the appropriate place.

I needed a power supply cord which could be plugged into the
cigarette-lighter jack of a 12 volt portable power pack I already had
for my car, and then into the power jack of my ETX 125. The Meade D.C.
cord is 25 feet long for use with an auto, an unnecessary length when
using a portable power pack placed close to the scope (moreover using a
25' cord for the few feet needed from power pack to scope provides an
unnecessary voltage drop).

Radio Shack car power adapter 270-1558 is carried as a stock item at
$10.99. It is rated at 5 amps (well above that needed for the ETX 125
and smaller aperture versions), comes with an eight foot cord, is fused,
and has a green power light. A nice feature of this cord is that its
non-cigarette lighter end is a plug allowing different sized tips to be
plugged into it, adjustable for either positive (+) or negative (--)
center pin. The power cord comes with your choice of one tip, selected
from a variety of tips they carry. The tip and size needed for the ETX
jack is: positive center (+) size "N".

The polarity of the tip (center pin) is set (as explained on the back of
the package) for the ETX, by plugging in the side of the tip showing the
(+) sign into the cord-jack side showing "Tip".

So, for a total of $11.84 you have a quality D.C. power cord at a length
suitable for a portable power pack, which can be placed out of the way
under the scope without worry of unnecessary voltage drop, or
entanglements with excess cord. The beauty of this cord is that it can
be used with other 12 v. devices having different size jacks, by buying
the necessary tip sizes.

As Mike passed to me in a separate e-mail, whenever changing from one
power source to another (e.g. from internal batteries, to external
source-- battery-power pack, or A.C. power supply [120 volt A.C. house
voltage to 12 v. D.C. out] ) you should do a "calibrate motor" to insure
the guidance encoders/sensors are calibrated to the new 12 v. power
source being used.

Joel Cohen

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