LED / Resistor Question - This should be easy for you to answer.

I noticed that on LED wiring diagrams the resistor is on the incoming current leg.  Is there any reason why the resistor could not be on the out going current leg?

If a resistor was installed on the out going leg then multiple LED could be tied in through one resistor rather than having an individual resistor for each LED.

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 You are right, it generally makes no difference which leg of the LED the resistor is on, but make sure the LED polarity is right (the longer wire is positive).  You can also have several LEDs strung together with one resistor.    

There is a good tutorial at http://www.theledlight.com/ledcircuits.html and a calculator for LED arrays which gives the wiring diagram at http://ledcalculator.net/
It doesn't matter which side it is on, the current and voltage will still be properly limited.
mischka7 years ago
It makes no different where you wire up the resistor (before or behind the LED).
lemonie7 years ago
Yes, you're right there, no functional reason to connect one way or another.

seandogue7 years ago
Nope. The resistor can be attached to the anode or cathode. Using the anode is mainly convention.