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Author Topic: SSTV/POV project- Step 1  (Read 1000 times)
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I am above your silly so-called "Laws", Mister Ohm.
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Yes, you can buy LCD panels for a buck on Ebay.

Yes, with the TVout Lib you can use any television as an output device with only two resistors.

Yes, for very cheap money, you can have a number of very high resolution output devices which perform wonderfully, with almost no effort at all.

Arduino is about making the difficult much easier.. so, I of course will be using the Arduino to take a relatively simple and inexpensive task and make it into a very involved and cumbersome technological nightmare.

How you ask?  By seeing if we can build our own TV screen, of course.  This started as an idea for a toy for my daughter to encourage her to head to bed early and shut off the lights (a continuous problem), but for that purpose I will use Plexiglas rather than actual glass, to prevent risk of injury from broken glass.  As I'm using a picture frame, this isn't even tempered or very thick glass, and would shatter into many sharp shards.  For toy purposes, almost any surface would work, but for what I'm attempting I may have better luck being able to illuminate the panel from behind.  A kid's toy would only need to work from the front, so you could just paint it directly on any surface.  I still would consider the lexan however, because it would provide a smooth surface and protect the actual paint layer, if you were "painting" with UV through the plastic.

I found a gift card I needed to use while unpacking xmas items.. so Home Depot and Rustoleum got $8 for a 7oz can of Phosphorescent Glow In The Dark paint, and the local discount store got a dollar for an LED keychain UV light.  Throw in a cheap photo frame, and we have a proof of concept on the basic idea.  

Already, it would make a cute toy for any kid, even us 40-something year old ones...  not "Arduino-ized" yet, but begs for it.  Even without the Arduino, I'd recommend this as a great home-made gift for a kid.

Once the screen itself is done, it's then time to think about the best way to provide for scanning across the surface, bitmapping our image.  I'm hopeful about being able to use either some lenses and a mirror with a UV source (by far the best reaction from the phosphor), or ideally a laser.  UV ranges would work the best, but standard red may still provide enough radiant energy to drive the phosphors.  UV lasers aren't cheap and can be dangerous, but blue/violet lasers are becoming cheaper due to blu-ray disc players.  Blue/violet laser pointers in the 405nM range are now becoming reasonable, but at this point I don't have one to mess around with.  As I don't have a blu-ray player to chop up, we'll start with UV led's and/or pocket cheapo red laser pointer.  Ideally (for a lot of reasons, not the least of which are financial) I try to use items in my projects that people ought to be able to pick up almost anywhere, and cheaply.  So far, the most expensive and esoteric item is the can of Glow In The Dark paint, which is made by Rustoleum and can be gotten at home stores, craft stores, and probably even at Walmart.. at $8 for 7oz (about 200ml).  

[media]http://www.youtube.com/watch?v=GaJeLafvdBw[/media]
« Last Edit: December 23, 2010, 02:07:43 pm by focalist » Logged

When the testing is complete there will be... cake.

Silly-con Valley, Ca, U.S.
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Very cool. I like. Lot's of ideas coming to mind.

A round "radar" type screen
As you said, mirrors to scan across tube TV style (wonder what kind of resolution and refresh rate you could get?)
Steppers on an x/y for an Etch-a-sketch style toy

Wonder if you could make a makeshift UV laser by enclosing the UV LED(s) in a mirrored chamber with a single pinhole exit. Maybe a couple of lenses if it's flaring a bit.
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10 PRINT CHR$(7)
20 GOTO 10

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Yeah, I'm hoping I can use a lens or two and spin a few mirrors and get away with that, basically doing a poor-man's raster scan.  The arduino could easily handle the timing, the phosphor retention once dry is quite long, if you wanted to, you could take the better part of a minute to draw a video frame and the phosphor would still be working for you if you hit it at close range with UV.  When I said "SSTV", I meant SLOW scan.  I know there's got to be a few HAM guys here, and probably a few have SSTV stuff on a shelf.

People I think likely have SSTV equipment on a shelf:  Cr0sh, Grumpy Mike, Westfw.. a few others.  

I may even build the world's ghetto-est Oscilloscope.  In fact, I think that's kinda a stepping stone, anyway... that's just a single scan line.  Using a couple of motors, I may just be able to drag the LED around on the glass for a totally hackjob solution.
« Last Edit: December 23, 2010, 02:22:50 pm by focalist » Logged

When the testing is complete there will be... cake.

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