Qwerk Customization and Tekkotsu

Index Adding a switch Adding a bump sensor Adding an LED Adding raygun special effects Adding a range sensor

Adding an LED

Adding an LED to your qwerkbot is a surpisingly easy task to mess up, however if you remember these simple rules, you'll have a working Light Emitting Diode in no time.

Rule 1

LED's have polarity! That means that the two wires coming out of your LED are not reversible. You have to know which side is positive and which side is negative in order to properly place it in your circuit.
Simple Ways to tell:
- Positive usually has a longer wire
- Negative usually has a flat side on the diodes plastic casing
- Positive has the symbol '+' and Negative has the symbol '-' (when in doubt follow this rule first)

Rule 2

You need a resistor. Also this resistor needs to be chosen carefully. If the resistor is the wrong size then the LED can be damaged. Use this simple equation to determine what type of resistor you should use.

resistor = (Power voltage - LED voltage drop) / LED current rating.

Rule 3

Follow this diagram. In the case of the qwerkbot, this means connecting the +5V(or more likely a digital output) to the positive side of your diode. Then connect the negative side of the diode to your resistor. Finally the other end of the resistor should be connected to ground.

Congratulations! You've just installed a Light Emitting Diode!

Scott McCaffrey and Dave Touretzky

Last modified: Thu May 13th 2008