Do three leg LEDs have a polarity?

[Che_Guitarra]

Sorry if this question is so basic and might cause offence

I'm building a guitar pedal with a three leg LED in the kit - first time i've ever toyed with one.
Three-leg LED polarity - there's no labelling on the PCB to advise a correct polarity, not does the LED seem to have any orientation indicators, so I guess i'm safe. But I better ask, just to be sure.

 

[David Kulka]

All LED's (all diodes) have polarity. You can check polarity with a DVM that has a diode check function by trying the leads in each direction and seeing which way causes the LED to glow. Or just try in your circuit in both directions and see which way works. Or check the datasheet if you can find it.

 

[JohnRoberts]

The three leg LEDs I've used in the past had a common cathode for the center lead. Look for a data sheet describing the LED.

JR

 

[pucho812]

Yes they have polarity.
A 3 leg LED is usually a bicolor LED. It Will have 2 X anodes and 1 X cathode aka 2 X positive connections and 1 X negative connection.

Depending which + gets voltage will determine color. Center leg is usually cathode as JR said.

 

[Script]

Yes, common cathode or, and they also exist, common anode.

Easiest and fastest is to just try loosely in that circuit they go into before heating up solder.

 

[micolas]

Bi-color LED R,G
Tri-color LED R,G,Y (through simultaneous lighting, red and green are composed and yellow light results)

 

[Cqwet Dbdfte]

Look at the data sheet for the product. They can be common anode or common cathode, usually the longest pin is common.
Three color LED could also be a COB, driven with a serial signal.

 

[Admiral-dk]

The Colours can be any combination that can be made with LEDs !!!!

You can NOT be sure that it is a Common Anode or Cathode - without either Datasheet or measuring it ...!!!

Usually one Pin is longer than the rest and more likely than not an Anode (positive) - just like Electrolytic Capacitors now-a-days ....

Per

 

[Cqwet Dbdfte]

With a 4V source and a resistor you can check most if not all LEDs

 

[Che_Guitarra]

Thanks everyone.

Unfortunately the kit didn't come with any component documentation to check that way.
But the suggestion of it doesn't work one way, flip it the other way got me there!