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Power LED from 3.3V Power Pin without Resistor

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2

I tried wiring one white LED to the 3.3V pin on a Pi Zero W with a 330 Ohm resistor but it's not as bright as I would like. If I wire it up without a resister I get a good amount of brightness. Is that a viable solution? Or should I try a smaller resistor?

If it matters, the power supply is a standard 5V 2.5A supply like this one. The LED is this one.

power led

share|improve this question

asked 1 hour ago

MichaelMichael

1504

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  I'd recommend 10Ohm resistor
  
  – Jaromanda X
  1 hour ago
  

  
  
  
  

add a comment | 

2

I tried wiring one white LED to the 3.3V pin on a Pi Zero W with a 330 Ohm resistor but it's not as bright as I would like. If I wire it up without a resister I get a good amount of brightness. Is that a viable solution? Or should I try a smaller resistor?

If it matters, the power supply is a standard 5V 2.5A supply like this one. The LED is this one.

power led

share|improve this question

asked 1 hour ago

MichaelMichael

1504

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  I'd recommend 10Ohm resistor
  
  – Jaromanda X
  1 hour ago
  

  
  
  
  

add a comment | 

I tried wiring one white LED to the 3.3V pin on a Pi Zero W with a 330 Ohm resistor but it's not as bright as I would like. If I wire it up without a resister I get a good amount of brightness. Is that a viable solution? Or should I try a smaller resistor?

If it matters, the power supply is a standard 5V 2.5A supply like this one. The LED is this one.

power led

share|improve this question

asked 1 hour ago

MichaelMichael

1504

share|improve this question

asked 1 hour ago

MichaelMichael

1504

share|improve this question

asked 1 hour ago

MichaelMichael

1504

asked 1 hour ago

MichaelMichael

1504

asked 1 hour ago

MichaelMichael

1504

1 Answer
1

active

oldest

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3

You need to consider that the forward voltage of a white LED is likely in the range of 3.0 V to 3.2 V (according to the linked article). Assuming the best case of 3.0 V and a resistor of 330 Ohms and using Ohm's law R = U / I we find that the current is about 1 mA and thus the brightness of the LED is rather low. Decreasing the resistor will help to some degree but be aware that this is borderline in any case. Say 33 Ohms will get you about 10 mA which might be ok. Best bet is to use the 5 V instead and design the resistor in such a fashion that the current suits the safe operational range of the LED.

Connecting a LED to a voltage source without a current limiting resistor is not a safe way of operating a LED. It is therefore not advisable to do so.

Find a more elaborate description of the calculations here; even though it is aiming at GPIO pins the physics still apply.

share|improve this answer

answered 1 hour ago

Ghanima♦Ghanima

12.6k114080

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Great input - thanks so much!
  
  – Michael
  1 hour ago
  

  
  
  
  

add a comment | 

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3

You need to consider that the forward voltage of a white LED is likely in the range of 3.0 V to 3.2 V (according to the linked article). Assuming the best case of 3.0 V and a resistor of 330 Ohms and using Ohm's law R = U / I we find that the current is about 1 mA and thus the brightness of the LED is rather low. Decreasing the resistor will help to some degree but be aware that this is borderline in any case. Say 33 Ohms will get you about 10 mA which might be ok. Best bet is to use the 5 V instead and design the resistor in such a fashion that the current suits the safe operational range of the LED.

Connecting a LED to a voltage source without a current limiting resistor is not a safe way of operating a LED. It is therefore not advisable to do so.

Find a more elaborate description of the calculations here; even though it is aiming at GPIO pins the physics still apply.

share|improve this answer

answered 1 hour ago

Ghanima♦Ghanima

12.6k114080

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Great input - thanks so much!
  
  – Michael
  1 hour ago
  

  
  
  
  

add a comment | 

3

You need to consider that the forward voltage of a white LED is likely in the range of 3.0 V to 3.2 V (according to the linked article). Assuming the best case of 3.0 V and a resistor of 330 Ohms and using Ohm's law R = U / I we find that the current is about 1 mA and thus the brightness of the LED is rather low. Decreasing the resistor will help to some degree but be aware that this is borderline in any case. Say 33 Ohms will get you about 10 mA which might be ok. Best bet is to use the 5 V instead and design the resistor in such a fashion that the current suits the safe operational range of the LED.

Connecting a LED to a voltage source without a current limiting resistor is not a safe way of operating a LED. It is therefore not advisable to do so.

Find a more elaborate description of the calculations here; even though it is aiming at GPIO pins the physics still apply.

share|improve this answer

answered 1 hour ago

Ghanima♦Ghanima

12.6k114080

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Great input - thanks so much!
  
  – Michael
  1 hour ago
  

  
  
  
  

add a comment | 

You need to consider that the forward voltage of a white LED is likely in the range of 3.0 V to 3.2 V (according to the linked article). Assuming the best case of 3.0 V and a resistor of 330 Ohms and using Ohm's law R = U / I we find that the current is about 1 mA and thus the brightness of the LED is rather low. Decreasing the resistor will help to some degree but be aware that this is borderline in any case. Say 33 Ohms will get you about 10 mA which might be ok. Best bet is to use the 5 V instead and design the resistor in such a fashion that the current suits the safe operational range of the LED.

Connecting a LED to a voltage source without a current limiting resistor is not a safe way of operating a LED. It is therefore not advisable to do so.

Find a more elaborate description of the calculations here; even though it is aiming at GPIO pins the physics still apply.

share|improve this answer

answered 1 hour ago

Ghanima♦Ghanima

12.6k114080

share|improve this answer

answered 1 hour ago

Ghanima♦Ghanima

12.6k114080

answered 1 hour ago

Ghanima♦Ghanima

12.6k114080

answered 1 hour ago

Ghanima♦Ghanima

12.6k114080