Poor man's ambilight

[spic0m]

Hi all!

I presume most of you are familiar with the ambilight range of tv's from Philips. If not check them here.
The moment i saw it i liked it, but, it's too @@@@ expensive for me and has another big drawback, i don't watch tv! So i decided to take the idea and customized it to my needs.
Which are: Having the ambilight effect with just white light for starters for my pc and also act as a dimmable desk light when i work and others sleep.
So it's going to be a 2 in 1 project and made as simple and cheap as it can be (with some finesse of course ).

[spic0m]

The idea is simple, first we make a rectangular frame the size of the screen, in our case 17" (remember the poor , then we drill some holes in it and fit some ultra bright white leds. A preview you can see in the pictures and also the led holders i'm going to use. The above combined with some cheap electronics hopefully will give us the desired result. The frame will be U shaped aluminum bars 12x12x12 2mm thick, which i plan to cut in 45 degrees and glue together with some J-B weld. All this is going to be controlled from switches located untill now in a place i havent imagined yet . May be in the side of the screen or on my desk, time will tell. Thats the structural part of the project so far, the bars have been ordered and on their way.

[spic0m]

Now for the electronic part of the project. First of all it must be consisted of cheap parts that do not require programming for 2 reasons, one is that i'm not that good with electronics and second, i'm worst in programming    . Eventhough i want it to be classy, so here's what i came up :

The ambilight effect will be given from the Ambient light level equalizer circuit, with the light sensor facing the screen.
The desk light dimmer will be the Voltage Controlled PWM Generator or the PWM Fan controller using a 555, haven't decided yet, any suggestions?
For on/off i will use a simple touch switch and a plain toggle for changing between the 2 modes.

That's all, i will start making the circuits for test in a breadboard the next few days and keep you informed.

[spic0m]

Small update due to heavy workload.
I made the touch in a breadboard and the schematics for it. I used a 4.7 uF capacitor instead of 10nF in the schematic because it was too sensitive. Also a 74LS109 flip flop was used as a toggle switch to hold the on/off state and this as relay driver.
Next days, time permited, i will make the other circuits in breadboard also to test them and schematics for them.

[kam]

the sensor has one or two wires?

[spic0m]

One

[spic0m]

Here are the schematics and pics of the triangle wave generator and the LDR circuit. In the schematic of the LDR the LDR itself is not the correct symbol since i couldn't find it in the eagle library (damn ignorance). The output of the triangle generator goes to the input of the LDR circuit (pin 3 in the 741). Now only left the dimmer to make and the rest of the materials to arrive. Be patient.

[spic0m]

Small update:

Having some troubles with the touch switch, is activating in random times, so on his way for the tech labs and their oscilloscope. Waiting for the results.