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

Hello World.

Hi,

I'm Chris, I'm an Engineering Student, and this is my blog to share and help myself document (and hopefully finish) my various electronic/software projects.

A lot of my projects will be based around the arduino, and nearly all will be building on, based on or exact replica's of projects other people have completed I've seen on the arduino playground, instructables or similar. Where possible I will try and reference the original project or idea that inspired me (because that's just fair), however please don't be offended if I have lost or forgotten the link and have not referenced you/someone you know of.

Anyway, here is a list of projects I'm hoping to undertake (at some point!):

• DIY portable projector
• Standalone Arduino Oscilliscope
• RGB Audio Spectrum Analyzer with a range of animations
• Build a RepRap!

 Obviously as a student, time and money are in very short supply, so progress will be slow, but I will update the blog whenever progress is made.

Thanks,

Chris