UV LED Exposure Box

Step 7 UV LED Panels

I've mounted everything except the LEDs on the copper side of the board to keep the LED side uncluttered.

Comments

[rykonen]

I love this instructable. How do I figure out how much power my LED's will need? I want to do four times the amount you have here... Could I just repeat the LED corn rows a few more times before I run it to the 12v ? (That idea doesn't seem right some how...)

[Nazdro]

Hi,

I'll assume you're using the same kind of LEDs and resistors that are specified then for every veroboard you've got 84 LEDs in bundles of three connected in parallel. Thus for every bundle you've got a forward current of:

I_f = (12V - 3x3.4V)/75ohm = 1.8/75 =24mA

So one veroboard, with 84 LEDs, will draw a current of

I_vero = (84/3)x24mA = 672mA

So if I've understood you correctly you wish to have 8 veroboards of UV LEDs then after you've connected them in parallel the total power drawn from the source would become:

P_total = 12Vx(8x672mA) = 12Vx5.375mA = 64.5W

So you'd need a 12V 65+W power supply, though to be on the safe side I'd personally use a 75W. Though as I said, you might be using LEDs with a different forward voltage so here's a formula where V_f is the forward voltage of your diodes:

P_total = 2304(4-V_f)/25 W

[rykonen]

Looks like I will be able to use certain laptop chargers, as some of them have these exact specifications. Very cool. Thanks again.

[Nazdro]

You're welcome, and I hope it works out for you :D. Though as with all such things, take care that everything is unplugged when you're working on it. 5 amperes are quite the punch if they ever decide you're the path of least resistance.

Just out of curiosity, what kind of setup needs that big an exposure surface?

[rykonen]

The box I have is big and I want to be able to make stencils for screen printing, as well as other things like guitar amps and synthesizers in the future... :) oh summer!

[rykonen]

Wow, thank you! That was incredibly helpful. It's nice to hear these formulas from a couple different places to get the application correct.