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# DIY Electric Art (LED Poster) -- Has someone made one before or is this just too easy of a DIY? Answered

Here is a link to what I am talking about in the title --> http://www.electric-art-gallery.com/justification_cars.htm

You can purchase the regular poster on websites for like \$6. It seems to me like all they do is add a couple LEDs and an on/off switch and pump up the price to ~\$120. Seems a bit like highway robbery to me.

Anyway, I just thought these LED posters were cool and would like to try tpo make one, but I am a bit unexperienced in the use of LEDs and resistors and the sort. Any help out there?

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## Discussions

awesome, thats really helful. I take it no one has any type of instructabke made for how to go about mounting the leds on a board(which in turn the poster is mounted to)?

HA, our Teched Room has that poster

Here's a run down on LEDs

Minimum voltage to light (voltage drop):
Red-1.7
Orange/Yellow - 2
Green - 2.1
White/Blue - 3

How to determine the resistor (formula):

Voltage input - Voltage drop X 50 = Resistance in ohms

(BTW the x 50 comes from 20mA LEDs take, 1/0.02 = 50, and it's easier to do that than a small divide)

Example, power source is a 9 volt lighting up one red LED
9-1.7 = 7.3
7.3 x 50 = 365
you need a 365 ohm resistor, give or take some, you don't have to be super exact with the resistor

Another example
source is a 12 volt wallwart
lighting up 3 white LEDs in series
12-3-3-3 = 3
3 x 50 = 150
you need one 150 ohm resistor in series with 3 white led's when the power source is 12 volts.

oh, and when in series you can use 1 resistor, but in parallel each LED should have it's own resistor.