Monthly Archive for December, 2009

More DIY Greenie Progress

Published on December 24, 2009 in Lasers. 0 Comments Tags: , , , , , , .

Using some crystals generously donated by Kenom, I managed to confirm that the diode I purchased lased at 808nm.   This rules out one theory on why I am not getting output from my original crystals.  These new crystals were used in a cheap laser pointer, so they are bonded together into one package.  As a result, it’s fairly easy to put them in front of a beam and watch the green on the other side.  However, my original crystals are unbonded, which leads me to believe that there is an alignment issue.  The diode that originally pumped those crystals had a countersunk hole for the mounting screw; the diode I’m currently using does not, so it doesn’t quite align as the original diode did.

Yes, I literally stuck a huge chunk of aluminum on the back of the LM317 because it was overheating and the output current was dropping.

icsy – I Can’t Sleep Yet!

Published on December 22, 2009 in News and Projects. 1 Comment

Throughout this past semester, I was continually impressed by the benefits of powernapping.  However, unfortunately, I’m one of those people who shut off their alarms and go back to sleep all the time.  So, my 20-minute powernaps became full nights’ rests.  Normally, I wouldn’t mind that, but it made things very difficult when I had a major assignment due the next day.

So, I present icsy:

http://jwcxz.com/projects/icsy

icsy (I Can’t Sleep Yet) helps to prevent you from falling back asleep after waking you up by asking you some simple math questions to get your mind going again.  You can customize all sorts of features including the alarm time, snooze time, number of questions, and audio file or alarm command.

It’s very easy to use.  Just invoke icsy -h for instructions.

Modding a Projector to use LEDs

Published on December 20, 2009 in Projects. 2 Comments Tags: , , , , , , .

I bought a Polaroid Polaview 350i projector off of eBay a few weeks ago for about $30–not bad considering that it retailed for a few thousand when it was being made.  Of course, projectors that are sold on eBay usually don’t come with bulbs; their owners decided that the price to replace the bulb (at roughly $200-300 a piece) simply was no longer worth it.

I bought the projector originally with two ideas in mind: if it turned out to be totally broken, then I would just salvage the optics in it; there are some pretty cool lenses and cubes in there that are easily worth $30.  If I could find a cheap bulb, then I’d just install it and get the projector running immediately.

Well, I couldn’t find a cheap bulb and I didn’t have the heart to tear it apart since it seemed to be in great condition (although it’s missing the remote).  So, I decided to try building and installing an LED replacement for the projector lamp.  Based on my research, there have been several attempts to do this.  However, those that I came across all used standard white LEDs, which have very little light output compared to the original bulbs.

A company named CREE makes high-quality lighting-class LEDs.  Their XP-G LED is the most efficient on the market and I intend to use 7 of them on a prebuild board from Cutter Electronics.  This will provide just over 2400 lumens, which is a little over the original bulb’s specification (~2200 lumens).

Interfacing the LED bulb with the original electronics will not be easy.  The projector uses a HID mercury arc lamp.  These lamps require a 5kV pulse to ignite, followed by about 50V to run.  If I can kill the initial pulse somehow, then I should be able to use the 50V supply to power a simple buck converter.  Also, I need to bypass the lamp checker; the projector won’t start up if it doesn’t think that there’s a bulb in there.

Anyways, here are some pics:

(horrible picture, sorry)

It worries me that little shards of glass fell out of the device. I might have to replace some optics that are difficult to get to.

The big RGB cube is under here. After I got the mainboard off, I realized just how difficult it will be to mess with the internals of this thing.

I’ve also started a page for my ongoing work.

Three More Weeks…

Published on December 1, 2009 in Computers. 1 Comment

It’s December.  That means three more weeks until I have a normal sleep schedule again.  Anyways, here’s what my desktop looks like this month.  I’ve switched to zsh, which is faster and much more powerful than bash.  It also supports all kinds of really advanced autocompletion, which can be helpful when you’re trying to remember the syntax of some command you don’t use very often.