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LED and Resister Question

 
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Last Post by Ron 2 days ago
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huckOhio
 huckOhio
(@huckohio)
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Joined: 5 years ago
Posts: 217
Topic starter 2024-09-03 6:52 pm  

I am helping my wife with a craft project and I going to use a CR2032 (3v) battery, switch, and a white LED to shine the LED light into the edge of a piece of acrylic to illuminate the etched design.  

The battery is 3v and the spec for the LED is DC 3V-3.2V Volt 20mA, Polarity (3 V).  Do I need to use a resister with this?  How do I determine the value I should use (I want the LED to be bright).

 

Thanks, Mike


   
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THRandell
 THRandell
(@thrandell)
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2024-09-03 7:53 pm  

Hi Mike @huckohio

Check out this article: https://learn.adafruit.com/all-about-leds

Tom 

To err is human.
To really foul up, use a computer.


   
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robotBuilder
 robotBuilder
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2024-09-03 7:57 pm  

@huckohio

The specs you quote are saying the LED can have a voltage of 3V-3.2V Volts between its terminals so you should be able to just connect it directly to the 3v battery. If the battery were say 6 volts you would need a resistor in series with the LED to drop the voltage by 3v across the resistor and 3v across the LED. You can use ohms law to compute the value of the resistor.

https://www.circuitspecialists.com/blog/5-steps-to-calculate-the-resistor-value-for-leds/

 


   
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huckOhio
 huckOhio
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Topic starter 2024-09-03 7:58 pm  

@robotbuilder 

Great.  That was my unscientific/unsubstantiated guess.  Thanks! 


   
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huckOhio
 huckOhio
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Topic starter 2024-09-03 7:59 pm  

@thrandell 

Thanks Tom.  I will read the article.


   
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 aliarifat
(@aliarifat)
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2024-09-10 4:10 pm  

You can directly power these LEDs with the CR2032. 


   
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Ron
 Ron
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2024-09-10 11:11 pm  

@aliarifat Please learn to use the Reply link!

First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, and 360, fairly knowledge in PC plus numerous MPU's and MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.


   
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Ron
 Ron
(@zander)
Father of a miniature Wookie
Joined: 4 years ago
Posts: 7590
2024-09-10 11:18 pm  

@robotbuilder I have seen a couple of online LED resistor calculators. The interesting part is they produce different results. This one seems to be the best of the lot, but I am more than willing to be convinced otherwise https://kitronik.co.uk/blogs/resources/led-resistor-value-calculator

First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, and 360, fairly knowledge in PC plus numerous MPU's and MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.


   
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