Hey all,
Finally getting going on this, now that i've found out that i've passed all my exams.
Basically, I'm making a Light Table (Or Light Box) using LED's. Traditionally, these are made using fluorescent lights. However, when you're tracing drawings for 5 hours over them, you roast and become very dehydrated. So i figured one out of LED's would be a)less painful on the eyes b)lighter, skinnier, and generally more mobile, and c) less roasting.
Basically, im not too knowlegable about circuits. I know a limited amount, but not enough to make this circuit. I've a few questions, so maybe someone could help me out:
Problem 1: The power adaptor:
I did some research, and i've decided to use a normal DC adaptor. The wire itself coming out of the plug is split in 2, so i'm guessing thats a + and - wire. (is there some way to tell which one is which?) It's an old Minidisc charger. The other problem with this is that it's only a 3v charger. My questions for this is, 1) How can i tell which wire is + and which is - (One of the wires has a white stripe on it by the way) and 2) will 3v be enough to power the leds?
All the info text on the lable says:
Input: AC230-240V~ 50Hz 5W
Output: DC3V - 500mA
Problem 2: LED to Dimension Ratio??
Ok, so the dimension of the illuminated surface is 600 x 900 mm (or approx 64 x 35 inches). Now, i know how to diffuse the LED's. They're actually going to be sort of dual-diffused. Firstly, the LED's themselves will be diffused, but also, the plexiglass they'll be illuminating will be diffused too. The main problem here, is deciding how many LED's ill need. Fixing them to the surface is no problem at all. They'll be approx 50-75mm (2-3 inches) away from the plexiglass.
Problem 3: LED colour?
This is a tricky one. White would be the obvious choice here. HOWEVER, i also came across an interesting article which explained how blue led's are better for your mood than any other light. To quote: "446 to 477 nm wavelength light is supposed to be the most effective for treating seasonal affective disorder (second to natural sunshine, of course)." which is blue.... SO the new problem is, do i chance Blue LED's? They probably would be bright enough that we could still see the pencil through it, right??
Problem 4: On/off switch?
With this one, i was just wondering how hard it would be to put a simple on/off switch in to the circuit?
AND FINALLY, Problem 5: The circuit
All these things in mind, could someone possibly give me an idea of what way to go about the circuit, like for resistors, series/parallel etc? i just do not know where to start.
Thanks all,
tm
Finally getting going on this, now that i've found out that i've passed all my exams.
Basically, I'm making a Light Table (Or Light Box) using LED's. Traditionally, these are made using fluorescent lights. However, when you're tracing drawings for 5 hours over them, you roast and become very dehydrated. So i figured one out of LED's would be a)less painful on the eyes b)lighter, skinnier, and generally more mobile, and c) less roasting.
Basically, im not too knowlegable about circuits. I know a limited amount, but not enough to make this circuit. I've a few questions, so maybe someone could help me out:
Problem 1: The power adaptor:
I did some research, and i've decided to use a normal DC adaptor. The wire itself coming out of the plug is split in 2, so i'm guessing thats a + and - wire. (is there some way to tell which one is which?) It's an old Minidisc charger. The other problem with this is that it's only a 3v charger. My questions for this is, 1) How can i tell which wire is + and which is - (One of the wires has a white stripe on it by the way) and 2) will 3v be enough to power the leds?
All the info text on the lable says:
Input: AC230-240V~ 50Hz 5W
Output: DC3V - 500mA
Problem 2: LED to Dimension Ratio??
Ok, so the dimension of the illuminated surface is 600 x 900 mm (or approx 64 x 35 inches). Now, i know how to diffuse the LED's. They're actually going to be sort of dual-diffused. Firstly, the LED's themselves will be diffused, but also, the plexiglass they'll be illuminating will be diffused too. The main problem here, is deciding how many LED's ill need. Fixing them to the surface is no problem at all. They'll be approx 50-75mm (2-3 inches) away from the plexiglass.
Problem 3: LED colour?
This is a tricky one. White would be the obvious choice here. HOWEVER, i also came across an interesting article which explained how blue led's are better for your mood than any other light. To quote: "446 to 477 nm wavelength light is supposed to be the most effective for treating seasonal affective disorder (second to natural sunshine, of course)." which is blue.... SO the new problem is, do i chance Blue LED's? They probably would be bright enough that we could still see the pencil through it, right??
Problem 4: On/off switch?
With this one, i was just wondering how hard it would be to put a simple on/off switch in to the circuit?
AND FINALLY, Problem 5: The circuit
All these things in mind, could someone possibly give me an idea of what way to go about the circuit, like for resistors, series/parallel etc? i just do not know where to start.
Thanks all,
tm