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LED's Polarity?
- Thread starter Bill Blue
- Start date
MikeH
Diamond Level Sponsor
This may help. There's a section on polarity down in the article, under the heading Considerations in Use.
http://en.wikipedia.org/wiki/LED
http://en.wikipedia.org/wiki/LED
RootesRacer
Donation Time
Diodes and other LEDs CAN be damaged on improper polarity if the avalanche voltage AKA zener voltage is exceeded. The avalance/zener voltage is an undesirable side effect of the reverse conduction function, which ideally is infinite in resistance, but in actuality not so.
To test, you would need an adjustable DC supply and an ammeter in series.
Increase the voltage till the current starts to increase to say 10ma.
If it goes to the rated voltage without the current going up, or ligting then you have the leads reversed. If the current goes up without discernible lighting, the the leads are reversed.
Dont put more than 10ma into the LED unless you know it can handle it since if its backwards, 10ma (at 12v) will produce a decent power dissipation and could heat damage the part.
Also it is possible that the LED has a diode bridge built in so as to handle either possible polarity at a small loss in efficiency.