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Bi Colour LED

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JMB

New Member
Hi, i admit to knowing very little about electonic Circuits etc. for my first project I want to design an indicator to show when my garage door is open or closed, I intend to use a Bi Colour LED for this purpose, ie Red open / Green closed. Do I place the the resistors on the Anodes or Cathodes ?. If the answer is to the Cathode how do I calculate the resistance.

Thanks
 

ericgibbs

Well-Known Member
Most Helpful Member
Hi, i admit to knowing very little about electonic Circuits etc. for my first project I want to design an indicator to show when my garage door is open or closed, I intend to use a Bi Colour LED for this purpose, ie Red open / Green closed. Do I place the the resistors on the Anodes or Cathodes ?. If the answer is to the Cathode how do I calculate the resistance.

Thanks

Hi and Welcome.
Do you have a part number for your LED.?

For single LED's it dosnt matter if the resistor is in the anode or cathode.
Some Bi colour LED's have a common Anode.?? and separate Cathodes.

A standard LED is usually run at 15mA or so.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
Yep welcome. Some Bi-color LED's are three leads and some are two. The three lead packages can be common anode or common cathode.

As for resistor placement or resistors placement for the 3 pin devices, it depends. You can use 1 resistor or two resistors.

We/you will need to know Vf and If.
 

SABorn

New Member
To be correct a Bi coloured led has 2 legs and a Tri coloured led has 3 legs.

For a Tri coloured led I would normmally place a resistor on each anode leg as then it can be used as a Bi or Tri coloured led.

For a Bi coloured led (2 legs) you would only use 1 resistor.

Pete.
 
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