# A Simple LED Tower

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## Introduction: A Simple LED Tower

I am fascinated by light. Especially different color light.
So I build this simple LED Tower with a few color changing LED's too.

## Step 1: Gather Parts

What you need:
a bunch of 1K ohm resistors
a bunch of LED's
a blank circuit board
solder
a soldering iron
a 9v battery clip (use and old 9v battery if you don't have a battery clip.)
a 9v battery

## Step 2: How to Solder

Solder all the negatives of the LEDs together.
Solder one side of the 1K resistors to the positive side of the LED's
Now Solder all of the other side of the 1K resistor together.

## Step 3: Power It Up

Now attach the 9v positive to the connected together side of the resistors and the negative to the LED's negative.

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## Questions

cool led project, I think for a 9V supply you can get away with using 500ohm resistors instead of 1kOhm for most of these type of leds, this will increase your brightness a little. do you know how to calculate the value of the current limiting resistor?

2 replies

No. I just know this worked but I really don't know why. I think I saw an LED connected to a 1 K resistor and it worked so for some reason it worked when I connected them all up.

if you know the forward voltage of your leds (usually ~3V) and the maximum forward current (usually ~20mA), you can calculate the minimum resistance needed with the following equation:

R >= [ (power supply voltage) - (forward voltage of led) ] / (max forward current in amps)

so for your leds it's probably around:

R >= (9V-3V) / 0.020A
R >= 300ohms

it's a good idea to pad this a little to prevent damaging your leds, 500ohms should be good. Using too much resistance will not hurt the led, but it will make it glow dimmer.