Sunday, January 09, 2011

Auto-Guiding for Poor Man

I finally got around to modifying my Vixen DD-1 dual-axis stepper motor controller so that it can be driven by PhD (through the GPUSB-AH module from Shoestring Astronomy).

The modification of the Vixen controller was quite straightforward and only took twenty minutes with a soldering iron. I didn't even bother to trace the circuit, but copied the picture from the Shoestring web site (first link above).

I also have a Meade DSI Pro Monochrome (first generation) that I used for some DSO imaging a couple months ago for my astronomy coursework at Swinburne. The problem with the DSI Pro is the tiny chip (Sony ICX424AL) so the field of view is tiny as well.

Since I had a William-Optics field flattener/reducer, I decided that I'll use my Zenithstar 70ED (with the flattener) as the imaging scope, with a DSLR, and use the DSI as the guide camera. My challenge was finding a suitable guide scope ("suitable" meaning "cheap") and securely mount it parallel to the imaging scope.

Based on some suggestions from Stuart on the SingAstro forum, I decided to use a camera lens as the guide scope. As I didn't want to butcher any of my collectible screw-mount Takumars, I decided to butcher this:



A Mamiya-Sekor C 80mm f/2.8 standard lens for the Mamiya M645 SLR. I also took a cheap Meade barlow and cut off the 1.25" eyepiece holder with a Dremel and cutoff wheel (actually a Bosch RTX.. same banana). After judicious application of epoxy, I was able to cement the eyepiece holder to the back plate of the Mamiya lens.



Next step was how to secure the Franken-guider to my Vixen Great Polaris. I did a bit of butchering on the DSI filter drawer holder by drilling two holes in it, then screwing the holder to a piece of wood:





I then epoxied the small piece of wood, to a larger piece of wood and let the whole assembly dry overnight:



After some trimming.. note my ingenious use of a somewhat longer M6 bolt with a wing head, instead of the original M6 hex-socket bolt, to both secure the wooden guider holder, and the original Vixen MT-1 motor.





And with the Meade DSI re-attached, and camera lens screwed on:





I actually got this working before with a less-robust wood bracket, and it guides just fine, except in declination where there's a lot of backlash.

Thursday, January 06, 2011

How to Uninstall Expired LauncherPro from Android Phone

LauncherPro is an abomination of an Android application that expires itself after some time. In fairness to the developer, it pops up some nagware screens every now and then. However it then goes off the deep end into pure evil-ness:

Once expired, LP will not let you do anything except launch a browser and go to the LP web site to download the latest version. There are two bad things about this:
  • not everyone has a data connection (my phone line has no data plan); other folks went roaming and disabled their data plan. Imagine their surprise when they get off the plane in their home country and find that LauncherPro has bricked their phone.
  • in my case, Wi-Fi was turned off. LP is so incredibly bone-headed, it won't let you access phone settings to enable Wi-Fi!
Some folks suggest using ADB from the Android SDK to force-uninstall LP. However this didn't work for me, as the phone needs to be in Debug mode for ADB to work.

Guess what.. with LP hogging the home button, you can't go to Settings to turn on Debug mode.

I finally found a workable solution: download the latest LauncherPro APK (or hopefully any other APK). Connect your phone to your PC and mount the SD card. Copy the new APK to the top-level of the SD card and rename it to something short (like lp.apk).

Unmount the phone, then in the phone browser (which is the only thing LP lets you run), type the following in the URL bar:

file:///sdcard/lp.apk

(notice the three slashes)

This will force-launch the Installer application on the phone. Now on my phone, it was set to disallow non-Android Market apps from installing; since the APK is not off the Android Market, the phone popped up an error and offered to let me change the application setting. Which launches the Settings application.

The Settings application also allows you to uninstall applications.

Which finally allowed me to get rid of that misbegotten abomination LauncherPro.

On the other hand, if your phone was already configured to allow non-Android Market apps to install, you may not get the Settings up. In which case, allow the newer LP to install and hopefully the expiration bricking would go away.

Me, I've sworn off LauncherPro forever. Get ADW Launcher instead.