Last updated: 25 April 2002
Subject: Thanks Dick! (AutoStar, External Power) Sent: Tuesday, April 23, 2002 16:28:51 From: email@example.com (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 cabling! Thanks Dick!! Doug Noyce Janesville, WI
And from our resident Autostar Expert:
From: firstname.lastname@example.org (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 programming. 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 --dickAnd:
From: email@example.com (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 --dickMike 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...)
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