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Resistor after LED?

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(@yurkshirelad)
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Joined: 3 years ago
Posts: 493
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I found this site https://ledcalculator.net and I created a simple circuit based on an LED in the Elegoo starter kit.

The data sheet for the Elegoo LED gives a max reverse current of 50uA for a blue LED. As a test, I entered these values into the site:

  • Power Supply: 5V
  • Forward Voltage: 3.3V
  • Blue LED Current Rating: 50mA
  • 1 LED

The site generated the attached circuit.

This is a basic question, but why is the resistor placed in the circuit after the LED?

Thanks

led1

 


   
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robotBuilder
(@robotbuilder)
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Joined: 5 years ago
Posts: 2042
 

@yurkshirelad
This is a basic question, but why is the resistor placed in the circuit after the LED?

Because it makes no difference in this case if the LED is first or second. They are connected in SERIES and the same electrons flow through both of them.

Imagine the LED is a turbine and the resistor is a valve and the battery is a pump and the wires are pipes carrying water.

circuit

   
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