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Topic: Simple LED circuit: position of Resistor important? (Read 820 times) previous topic - next topic

xberg

Hi,

climbing the steep learning curve of electronics...

In a simple LED circuit, is the position of the resistance important. ie, is:

Battery +  ----   LED --- resistor --- ground

the same as

Battery +  ----   resistor --- LED  --- ground

I would say it's exactly the same, and I could even replace the LED with a laser module and it would still be the same - it's not important where the resistor is. But am I right?

thanks,

XBerg

Anachrocomputer

Yes, you are right. The order of the LED and resistor is unimportant.  Sometimes, when we're dealing with multiple LEDs in one package (7-segment, etc.), then all the LEDs are joined together at one end, on a single pin.  In that case, we must fit one resistor on each LED, on the end that's not all connected together. But for individual LEDs, it doesn't matter.

xberg


RoyK

#3
Aug 05, 2011, 10:18 pm Last Edit: Aug 05, 2011, 10:59 pm by RoyK Reason: 1
One thing to consider if the LED is connected to the rest of the circuit by long wires is what might happen if one of the connecting leads shorts to something else (usually ground is exposed).

The Bat+ ==> resistor ==> LED ==> Gnd arrangement is unlikely to suffer damage if either of the LED leads shorts to gnd

However in the

Bat+ ==> LED ==> resistor ==> Gnd arrangement  shorting one of the LED's connecting wires to GND may damage the power supply and shorting the other will almost certainly blow the led.


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