DIY Standalone Projector

So,
I'm quite far through this project, but in this post I will write up what progress I have made so far.
All credit for the idea goes to these instructables:
http://www.instructables.com/id/DIY-Multimedia-LED-Projector/
http://www.instructables.com/id/homemade-projector-cornflake-box/

Essentially the idea is to create a homemade projector using a cheap LCD T.V. (I'm using a car reverse monitor), tear it out the case to reveal the translucent LCD screen then place a really bright light behind it and use a lens of some sort to focus it to a point on the wall.

 (This fantastic image has been shameless taken from http://www.instructables.com/id/DIY-Multimedia-LED-Projector/)

I'm using a 10W high power led as the light source and a second hand slide projector lens to focus the image, as for the lenses either side of the LCD in the diagram - I am going to try and get away without buying them. If the image produced is too out of focus then I will buy two credit card sized magnifying glasses. Also, the condensor lens has been omitted (mostly because I couldn't find one anywhere).

Some have said that there might be some difficulty in projecting a screen larger than a slide (1.8") with a slide projector lens - I can happily say that in a dark room with my brightness on my iPhone at the max, I have been able to project a video onto a white wall quite well. The LCD I am using should be the same dimensions as the iPhone screen (when it arrives from Hong Kong).

Electronics
I chose to use a 12V power supply as the LCD is intended to run off the car battery (12V). The LED runs at 9V (900mA) so I have a very large ceramic 5W resistor that I will use to drop the voltage. A very shoddily drawn circuit diagram below explains very simply what I plan to build (apologies if any of the symbols are wrong).

A Note on PWM: I intend on taking the +ve connector to the backlight on the LCD and connecting it through a transistor (now a MOFSET) to turn the LED on and off when the backlight would be turned on and off. I assume that the backlight is controlled by a PWM signal and by connecting that through the MOFSET I should be able to use the original brightness controls to control the brightness of the LED and projector.

Progress so far:

So I now have everything apart from the box, power supply and LCD display (on its way from china). In the mean time I tested the LED and resistor using the same circuit as in the diagram above, replacing the 'LCD Backlight In' with an arduino running the Fade Example (http://www.arduino.cc/en/Tutorial/Fading) which essentially sends out a PWM signal, adjusting the duty cycle to give the impression of dimming...and it worked!

Here's the video:

So that's all for now. There is a box waiting for me at the Post Office Depot, so hopefully that will be the LCD screen, and I should have an update once I've wired that up and bought a box from Maplin.

Thanks,

Chris