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Common Anode or Cathode

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jack0987

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The led segment lights with the connection shown in the picture.

Is this led common cathode or anode?
 

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crutschow

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Sounds like a homework problem.

You can answer that question if you know which lead of an LED is positive when it is illuminated.
 

MikeMl

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You dont even have to hook up the battery to tell :D

btw- you should never hook a battery directly (without a resistor in series) to any LED as you have done. Most of the time you destroy the LED when you do. You lucked out.
 
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jack0987

Member
It is not a homework problem.
I found a bunch of these in a box and had to identify all of the pins.
I used a 1k resistor. forgot to draw it.
My guess is that it is common cathode. Is it?
 
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MikeMl

Well-Known Member
Most Helpful Member
Since these always run on a positive supply, it is a common anode. The seven-seg decoder grounds those segments to be lit. Get the part number off it and Google it. You may find a data sheet.
 

jack0987

Member
Thank you. I just checked again but do not see any part number on the device or I would have looked up the data sheet.
I was going to run these off of a 4511 to experiment with. The parts list I have calls for a common cathode so I may not be able to use them in this case.
 
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