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Author Topic: Consistency is for whimps  (Read 426 times)

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Offline jwatteTopic starter

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Consistency is for whimps
« on: January 10, 2014, 11:45:11 PM »
I've got to vent just a little bit...

I just built some boards (my first mostly-successful SMD reflow board! yay!)
The Lite-On LTST-C170GKT green SMD LED has the band on the cathode.
The Lite-On LTST-C170CKT red SMD LED has the band on the anode.
So, each board has some LEDs that work and some that don't...

Offline Roman505

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Re: Consistency is for whimps
« Reply #1 on: January 11, 2014, 04:13:59 AM »
Some but not all people spell that "wimps", which is a little inconsistent, so I think you may have made a self-referencing joke to have delighted the late Martin Gardner. :)

Offline jlizotte

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Re: Consistency is for whimps
« Reply #2 on: January 11, 2014, 09:05:06 AM »
I had the exact same problem with some LED packs that I bought for making some light-painting tools. Incredibly frustrating. Now when I get my components in, I test each category or color of part for consistency, and label the bins I store them in if they aren't consistent. I feel for you. Been there, done that.

Cheers on the board, though!

John

Offline JonHylands

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Re: Consistency is for whimps
« Reply #3 on: January 13, 2014, 10:00:08 AM »
If the LEDs are not consistent, what you can do is take your multimeter and put it on continuity test (the one that beeps when you touch the two leads together).

Touch one of the leads to each end of the LED. If it lights up, the red probe is on the + side and the black probe is on the negative side. If it doesn't light up, switch sides and try again.

- Jon

Offline jwatteTopic starter

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Re: Consistency is for whimps
« Reply #4 on: January 13, 2014, 01:43:23 PM »
Quote
what you can do is take your multimeter and put it on continuity test

Yes, that's how I initially tested it once I found "it doesn't work."

Then I checked the data sheets, and in fact, this inconsistency is documented. Separate data sheet for the two models, with different polarity shown. I just didn't think to actually check for someone marking the polarity of a diode "the other way around." Now, I know :-)



 


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