Detecting LED ON or OFF

[silvarblade]

Hi, i want know how to detect whether an LED/Light is faulty or not?Since i want it to be independent of outside quantities so i am thinking of checking the current or voltage. I want to go with current since i can check it from the other point?What ideas do you guys have?

 

[birdman0_o]

Not sure what you mean by independent of outside quantities...I assume you mean not on because then it would it be shinning in your eyes or not, pretty straight forward test.

What do you mean by the other point?

If you mean it is already in a circuit and not working perhaps it's because a) your current is too low or b) your voltage is too low.

An led usually needs about 3V to be in it's active region. It runs off about 20mA of current.

Not sure how you can test it without applying a voltage...

Mike

 

[silvarblade]

Not sure what you mean by independent of outside quantities...I assume you mean not on because then it would it be shinning in your eyes or not, pretty straight forward test.

I mean that i dont want outside parameters to interfere with the test of an LED/Light being ON or OFF.For e.g i cant use a light sensor since it will get effected by outside light!


What do you mean by the other point?

If you mean it is already in a circuit and not working perhaps it's because a) your current is too low or b) your voltage is too low.


I know the current and voltage requirements of an LED iw ant to know whether it is ON or NOT say 'remotely'.
An led usually needs about 3V to be in it's active region. It runs off about 20mA of current.

Not sure how you can test it without applying a voltage...

Mike

Thanks for your reply.

 

[k7elp60]

Hi, i want know how to detect whether an LED/Light is faulty or not?Since i want it to be independent of outside quantities so i am thinking of checking the current or voltage. I want to go with current since i can check it from the other point?What ideas do you guys have?

I have used optocouplers on occasion to monitor an LED. The output of the optocoupler can control a mulititude of things and the voltage drop accross the optocoupler input is minimal.