Dumb question K or A positive on a board?

[wingnutLP]

I have an led on a board from Cutter. It has only A and K to denote + and - which one is which?:thinking:

I have tried google but it is not easy to find (because I am no doubt using the wrong search terms!).

Thanks

 

[darkzero]

Not a dumb question but in order to answer your question you need to provide more info, most importantly what LED is that you have. I would not rely on those letters, what if the emitter was mounted on the MCPCB "upside down" from a previous batch. Your best solution would be to look at the datasheet for your LED to see what cathode/anode are & follow the traces on your MCPCB.

Perhaps the letters on Cutter's MCPCB denote anode for A & cathode for K?

I recently had some XP-Gs from cutter but again I would not rely on the letters from my pic below unless you have the same emitter & it is oriented in the same way. The XP-G can be mounted 180 deg & would still work on this MCPCB.

 

[RaVeN38571]

Do you have a multimeter? If so, you can use the diode setting. It will light up if you have the correct polarity and will not if you don't. Won't hurt your emitter.

 

[darkzero]

Do you have a multimeter? If so, you can use the diode setting. It will light up if you have the correct polarity and will not if you don't. Won't hurt your emitter.

+1

:thumbsup:

 

[Rommul]

Is it possible A and K stand for anode and cathode?

 

[TorchBoy]

I have an led on a board from Cutter. It has only A and K to denote + and - which one is which?:thinking:

I got rather confused when I got some from there too, because the anode and cathode are the other way around with batteries. http://en.wikipedia.org/wiki/Led has the answer. The little diagram on the right shows that the anode (A) is positive and the cathode (K) is negative. And strangely enough, the diode setting on my multimeter verified that. (Yes, I know not all multimeters have that feature.)

I think there's a memory trick along the lines of "Cathode Collects Carriers" meaning electrons. So with a diode the cathode is negative, because electrons are going into it on the negative side, but a battery positive terminal is the cathode because, again, electrons are entering it there.

 

[wingnutLP]

Thanks all,

The led is a XP G and it is on a board that looks very similar to dark zero's photo. I don't have the board here but I will check tonight.

I think my multi meter may help to if I connect red on the mmeter to what I think should be positive on the board I should have a reading if I am correct?