Updated on : 31 dec 2008
How you can determine anode and cathode of LED?
I know its tooooo trivial but still …
(Most common method)
When you purchase an LED … longer leg is anode while shorter leg is cathode. What if you have cut the two leads to same length ?? read on …
- Take one resistor between any value between 100Ohm to 500Ohm and connect it in series with the LED on bread board.
- Give a supply (from 3 to 9V). If LED glows, lead connected to VCC is anode and other one is cathode.
What if you don’t have breadboard or you are too lazy (like me 🙂 ) to do this testing …
- Take multimeter and keep it on Diode testing mode.
- Connect one lead of LED to COM probe of DMM and another to RED probe.
- If you get some reading on DMM, then lead connected to COM is cathode and other one is anode. If not reverse the LED and recheck.
What if you feel (like me 🙂 ) this method is also too boring and time consuming …
- Take LED in your hand and look carefully at the place where leads go into LED.
- Look at the border ring which is slightly projected out.
- You will find, on one side, this ring is flat. That’s the cathode !!!! and other one is anode.
…and this will be True for almost all LEDs that you purchase from general retail electronic shops.