Led (anode/cathode recognition)
By CaptainTuna
2008-07-14 06:52
2008-07-14 06:52
here's the led i bought.. the lenght of the two 'bars' (don't know their name in english) and the fact that the capsule is flat on its right side make me believe the one on the left is the anode, but then i checked it inside...i haven't seen leds like this one but i haven't seen many of them (usually the widest part is linked to the cathode). so which one is the anode? (my guess is the left one)
Does it really mather to
Does it really mather to know which pin is the anode/cathode. I thought you can just hook it up, and either it works or it doesn't. But you can't break it by wiring it wrong. Am I right?
So my suggestion would be, just hook it up, and you'll see which pin is the anode/cathode. But I might be wrong about the 'won't break' part... so you better wait for someone to confirm this ;)
Yes and No
Well, you won't break it, but if you're debugging a circuit, you can remove 50% of the "unknowns" by knowing for a fact that your LED is the right way round!
NB I would call them "leads" or "tails."
actually you are
If you have a
If you have a measure-thingey, you can measure on it. One way current flows through, and that is the way to hook it up.
Sometimes I take off little IR LED's from old prints, and they are inside black plastic etc, so there is no way of telling what is what. If they are small and used for optical tracking, they do burn quite easlily, and are impossible to replace.
So.. Set up measure-thingey to measure resistance. Red on one leg, black on the other. If no result, make it the other way around. Then red is V and black is G.
Also see this: http://letsmakerobots.com/node/78 to know if it is working.
Sometimes the smaller ones blow if you get them too much voltage - no matter which way they are turned.
i'm not using ir leds :)
i'm not using ir leds :)
actually i just noticed that my multimeter...ops sorry, my bad.... that my measure-thingey has a setting which says "LED" and has 2 holes when i can insert my led in and i guess i don't need to use resistors in oreder not to destroy it (by inserting it in the measure-thingey i mean)
The longer tail is positive
The longer tail is positive (anode), the shorter tail is negative (cathode). Also, if you look closely, the cathode has a flattened edge. Another way is to look at the shape of the filament inside. The cathode is much larger than the anode.
An LED is a diode, so it will let current pass only in one direction. Hope this helps. And yeah, nothing bad happens(mostly) if you hook it up the wrong way! I wish other components were this forgiving! :)