Last updated: 25 April 2002

Another External Autostar Power Box

Subject:	Thanks Dick! (AutoStar, External Power)
Sent:	Tuesday, April 23, 2002 16:28:51
From: (Doug N.)
While my scope is down, I have spent my time finishing your book! One of
the items I found to my immediate liking was the issue about schlepping
the scope to the computer, to download software to the AutoStar. I had
thought of a portable power source, but without the pinout of the
connector,alas I would have to disassemble it, and maybe screw it up, so
I just used the scope to power the HBX.

That is until I read Dick's article in chapter 6 of 'Using the Meade
ETX', where Dick provides the missing pinout!

Needless to say I ran off to Radio Shack and bought the components to
build both an AC and a DC External Power Supply for the AutoStar.
Attached are the photos of the animals I built, each taking about 1/2
hour to build. It took me longer to find the tools and materials, than
to actually construct the boxes.

I  have included a short material list for those wanting to do the same,
RS catalogue numbers not given.

DC AutoStar Power:
1 small 'project box', large enough for a 9V battery
1 9V battery holder
1 9V battery
1 9V battery connector
1 12V Pushbutton on/off switch
1 12V LED indicator
1 6-12 ft, 8 conductor phone cable with 2 male ends

Materials cost:  $10.00

AC Adapter

1 120/12V transformer (on hand) about $10
1 smaller 'project box (to hold splices)
1 12V toggle switch
1 12V LED
1- 6-12 ft, 8 conductor phone cable (use other end of above)

Materials cost: $ 18.00

For those wanting to leave out the switches and LEDs, it would be even
less, but I prefer to have them on, so as not to connect hot cables to
the AutoStar, and the LED to know when it is on, and when not. Also a
good indicator for the battery life on the 9V version.

Pictures attached.

Along with the help I got from Dick's emails on my camera problems, he
also provided me with yet another service. The pinout of the Autostar

Thanks Dick!!

Doug Noyce
Janesville, WI
Autostar Power Box

Autostar Power Box

Autostar Power Box

Autostar Power Box

And from our resident Autostar Expert:

From: (Richard Seymour)
Very handsome lumps... however i cannot with clear heart recommend using
a typical 9v rectangular battery as  a power source for downloading...
one tends to forget time during such things, and dropping into the
"flakey power" range at the wrong moment can even wipe out the Safe Load

I haven't measured power consumption -during- programming, but the Init
phase can rise to 110ma (at 12v)

I'm not near my battery reference books to estimate 9v life under
typical Autostar loading (60ma minimum, 110ma max, with a 10ma kick when
it beeps)(20ma in Sleep mode)(<-- if memory serves)

ol' chicken
From: (Richard Seymour)
> It did work very nicely for a complete upgrade download on the 9v, just FYI.
> I would use the 9v only as a last resort for object chart updates, but the
> AC source is the one I keep connected.
> It has an 850 mA output @12vac

Yes, my ETX90 lives on a RadShack 500ma supply.  And its internal AA cells.
 (but not for a download)

I agree that a 9v rectangular can handle a half-hour operation. But i'd
start getting worried after that. Some folks just don't think about it,
and they're the ones who later post asking "how do i do a Safe Load?"
(conversely, i think there are far -more- folks who simply spaced out and
turned off the scope's power during a download)

Of course, the fast,(well, it'll take an hour) simple test is to set up
 your 9v system, press MODE to reach the Status (RA/Dec) display,
 scroll up to the Battery Level display... and just wait.
Tap the Zero key every once in a while to keep the 10-minute 
display time-out from tripping, and watch the level drop over time
(take notes every 5 or 10 minutes).
My autostar starts getting flakey around 6.8 volts/70%
Different vintages of Autostars have different internal 5v regulators.
Mine is an older one with a higher source-voltage requirement to maintain
the internal 5v.  Newer units can squeak almost another volt lower.
(so "flakey at 6v" maybe).  But i've only tested -mine- with a regulated
lab power supply.

have fun
Mike here: I always use the AC Adapter with my ETX-125EC so never worry about a dead battery during the download. Unfortunately I have to carry the whole thing into the computer room. (Gee, now that we can ethernet over electrical wiring, where's serial over electrical wiring...)

Return to the top of this page.

Go back to the Autostar Information page.

Go back to the ETX Home Page.

Copyright ©1999-2002 Michael L. Weasner /
Submittals Copyright © 2002 by the Submitter