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Problems with transistor relay driver circuit

Re: Problems with transistor relay driver circuit

‎09-25-2013 10:01 AM

Your particular LED may not light @ 20 mA (I know I suggested 20 mA earlier, but not all LEDs are the same, just my experience with the ones I have used). Try successively smaller current-limiting resistors or a pot until it lights up (you know already that it lights with a 0 ohm resistor, if only for a few seconds) but doesn't burn out.

 

You didn't put the already-blown LED back in, did you? Smiley Wink

 

Cameron

 

To err is human, but to really foul it up requires a computer.
The optimist believes we are in the best of all possible worlds - the pessimist fears this is true.
Profanity is the one language all programmers know best.
An expert is someone who has made all the possible mistakes.

To learn something about LabVIEW at no extra cost, work the online LabVIEW tutorial(s):

LabVIEW Unit 1 - Getting Started</ a>
Learn to Use LabVIEW with MyDAQ</ a>
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Re: Problems with transistor relay driver circuit

‎09-25-2013 11:45 AM - edited ‎09-25-2013 11:47 AM

according to your setup...you have approx. 4mA on the LED, depending on the spec sheet...might not be able to light it. hopefully you have replaced the burnt LED out. what is the normal forward current and forward voltage?

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