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LED Basics

 If your project does not include LEDs, you are probably doing something wrong. Here are basics for bringing light to the subject.

What you need:

  • Voltage Source.
  • Your favorite color LED.
  • The correct valued resistor.
  • Varies Jumpers
  • Optional toggle On / Off switch.
  • Optional Breadboard to work on.
LED Circuit

What we use in this document:

  • 5 Volt Bread board power supply
  • Clear lens, red LED
  • Correct valued resistor
  • Push button on / off switch
  • Breadboard
  • Jumper


LED Voltage

Component placement. This is where a breadboard is the greatest thing on earth. There are rails for positive and negative power, and pins in the middle for your components. Now your LED does require voltage in one direction ( Its a Diode! link? ). How do you tell which side is positive and negative? First refer to your datasheet that came with your LED other wise this diagram should help. If you get it wrong it is possible to 'fry' your led, so get some spares just in case.

From the positive side of your voltage source use your jumpers and wire it up to your switch. Out of the switch goes to the anode of the LED. Coming out of the cathode (Negative side) jump over to where your resistor is going. To calculate what ohms to use the formula:

Resistance in Ohms =
Power Supply Voltage - LED Voltage Drop
LED Current Rating

For the LED I am using I have a 5 V power Supply, the LED Voltage Drop is 2.4V. and the Current Rating is 20mA.

5 V - 2.4V = 2.6V. 2.6V / 20mA = 130 Ohms

Now 130 Ohms is not the only resistor to use for this LED. Basically its a minimum, anything less could fry your LED. Just for simplicity and for the fact that this one is right next to me, I will be using a 1000 (1K) Ohm resistor. The resistor basically connects between the cathode side of the LED to the negative side of your power.You can follow along in this photo. ( I do have an optional momentary push down switch in mine between the positive of the voltage and the Anode of the LED.


Basic LED Setup


Good luck!