DIY PocketPC based projector

I built a "projector" yesterday. It uses the same approach taken by the many DIY Projector plans (link1 link2) found on the net.

A projector consists of three basic elements: projection lens, image source, projection light. The projection lens is what magnifies the image from the image source. The projection light gives enough juice for the image from the image source to appear on the projection surface. The DIY plans usually make use of a Fresnel lens as the projection lens, a TV/LCD as the image source and metal halide bulbs are the projection light. These components can be obtained *relatively* cheaply.

Materials:
My projector is quite simple.

I decided to use my ageing HP 5550 Pocket PC as the image source. The screen has a resolution of only 320 x 240 pixels, but it is more than enough for watching movies or projecting the usual Pocket PC applications - atleast enough for my use. I then got a handy sized fresnel lens off Ebay for less than 2 quid. I used cardboard I had lying around to make the projector housing.

Construction:

1. The cardboard was fashioned into a box.


2. A rectangular hole was cut at one end to make room for the fresnel lens.


3. The fresnel lens was mounted on a separate piece of cardboard to be pushed into place inside the box.


4. The Pocket PC was positioned appropriately inside the box.


5. Finished product!


Results!
Since I had no screen and nor was I bothered to make one, the off-white colored wall in my room was to act as my screen. The projected image size was around 4 feet - a limitation due to the small size of my room.


Now, it's time for popcorn(not really) and a showing of Stargate Atlantis season 2! :-)

Toodles.

Hacking a SE T610 camera for IR

I hacked up my mobile phone camera a few months ago to make it sensitive to Infrared as well as the Visible wavelengths of light. I have been meaning to share the hack with others, so finally here it is!

Introduction
My phone, a Sony Ericsson T610, had been giving me trouble. There was static when I am in a call and sometimes my voice cuts out altogether. I had guessed it was the mic giving me trouble. I got out my hex screwdriver set and disassembled the phone and repositioned the mic after cleaning the contacts. Sure enough, that fixed the problem.

Curiosity got the better of me after fixing the mic. I wanted to check out the camera in the phone! I had modified a webcam before to make it senstitive to Infrared (IR). The CCDs (Charge Coupled Devices: the part of a camera that actually converts what it sees into electrical signals) are usually sensitive to IR as much as it is to visible light and camera manufacturers place an IR filter in the lens assembly to remove the IR spectrum. Anyway, I wanted to see if I could do the same to my phone camera.

I then had the camera carefully disassembled soon as it turned out to be quite easy. I proceeded to identify the IR filter in the lens assembly, removed it and reassembled the phone. I turn on the phone and viola! It works! Of course it works!

How to do it?!
Do this under a table light and use a magnifying glass to make things easier.

1. Take apart your phone. You'll need a hex screw driver of the right size.
2. Get to the camera and just remove the clips holding the camera onto the phone case, then remove the wires from the socket.
3. When you have the camera assembly separate from the phone, remove the back of the camera by prying apart the plastic clips that hold it together. Be careful when doing this!


4. You should see inside the lens assembly now. Look at the outer most lens, pasted using globs of glue at the sides. The lens would have a red tint to it. Use a sharp object, possibly a tiny screw driver to pry the lens out. Store it in a safe place. WARNING: You will most likely damage the lens if you are not ultra careful!


5. Reassemble everything once you get that lens out.

Switch on your phone. Bring the front of a TV remote control near your camera and see the IR being emitted by the remote!!

Exploring the IR World
What could this possibly be useful for? Since the camera is now sensitive to IR, it can see things that our eyes can’t see. This was mind boggling at first, well to me at least. I could darken my room and “illuminate” it with IR light which is invisible to the human eye. Turn my camera on and the room is clear as daylight!

First things first, you'd want to just snap pictures and see how they look. Amusing aint it? Well, you can do quite cool things in addition to taking weird images. You could even “see” the light from a TV remote. TV remotes rely on IR signals to communicate with the TV.

Your hacked up camera will now be able to spot security cameras in the night that use IR to illuminate the area. Such areas will be lit up and clear as day. I've had much fun at night with security cameras.

Got another SE T610? Try looking at the "opague" top black bit with the hacked camera. It would be see thru! Or try with a glass of coke. You'll see right through the coke and the coke will appear colorless!

Moreover, for you perverts like me. I encountered an interesting occurence - an IR sensitive camera seems to expose more than is visible to the naked eye when it comes to clothing. Those wearing certain types of clothes beware!

Further thoughts
I am dying to try this out with a phone with a better camera. The SE K700i/K750i would be ideal! These new generation mobile have better cameras, thus better quality pictures even for infrared. I could also replace the illuminator/flash LED in the phone with a high brightness IR LED. Now to get my hands on a willing K750i... Sigh. Have fun!