Resistor must be located before or after LED?

Other Hardware General Electronics
1

Hi, i am new to Arduino and quite new to electronics. going through the ARDUINO UNO projects book i just saw that at the first projects we locate the 220 ohms resistor before the LED (from 5V -> GND), and in the following ones the resistor is located after the LED, is it the same? is it an error?.....
thanks for any help
jesus

2

is it the same?

Yes it is. In a series circuit the order of components does not matter as the current has to pass through all the parts.

If you think this matters then you are misunderstanding how electricity works.

2 Likes
3

thanks Grumpy_Mike, yes you are right i was misunderstanding electricity...
appreciated

4

If you place LED correctly in direction of current flow it doesn’t matter. Only if you connect two resistors and use it as potential divider it matters.

5

I prefer this configuration.

+5v — resistor — T 1 3/4 LED — I/O pin.

This way, you can easily use the cathode lead of the LED as place to clip a scope probe etc. to.

6

i just saw that at the first projects we locate the 220 ohms resistor before the LED (from 5V -> GND), and in the following ones the resistor is located after the LED, is it the same?

Well spotted and karma for asking.