• Raspberry Pi GPIO

    From Mortifis@VERT/EMPTYKEG to All on Sunday, December 09, 2018 13:38:34
    Anyone familiar with wiring GPIO on RPI?

    I have seen a few examples of wiring a red LED directly from the RPI GPIO pins, however, I need to wire a GREEN LED and am having trouble calculating the resistor needed. I believe that a green LED uses 3.3 volts and at 20ma, so if I use the 5V power on pin 1 would I end up with 5V - 3.3V = 1.7.
    1.7 V = 20 mA × R or rephrased: 1.7 V / 20 mA = R and when we solve that we get: 1.7 V / 20 mA = 1.7 V / 0.020 A = 85Ω ?

    Thanks

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  • From MRO@VERT/BBSESINF to Mortifis on Sunday, December 09, 2018 12:22:17
    Re: Raspberry Pi GPIO
    By: Mortifis to All on Sun Dec 09 2018 01:38 pm

    pins, however, I need to wire a GREEN LED and am having trouble calculating the resistor needed. I believe that a green LED uses 3.3 volts and at 20ma,


    where do you get your 3.3 number? the chart i am looking at on the internets sez whites are in that range and greens are 2-2.3

    i can check out leds at work and see what the specs are.
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  • From Vk3jed@VERT/FREEWAY to MRO on Monday, December 10, 2018 10:09:00
    On 12-09-18 12:22, MRO wrote to Mortifis <=-

    @VIA: VERT/BBSESINF
    Re: Raspberry Pi GPIO
    By: Mortifis to All on Sun Dec 09 2018 01:38 pm

    pins, however, I need to wire a GREEN LED and am having trouble calculating the resistor needed. I believe that a green LED uses 3.3 volts and at 20ma,


    where do you get your 3.3 number? the chart i am looking at on the internets sez whites are in that range and greens are 2-2.3

    2-2.3 is more in line what what I remember as well. Certainly not 3.3. Yeah, white LEDs weren't around when I last studied this. :)


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  • From Mortifis@VERT/EMPTYKEG to MRO on Monday, December 10, 2018 10:38:27
    Re: Raspberry Pi GPIO
    By: Mortifis to All on Sun Dec 09 2018 01:38 pm

    pins, however, I need to wire a GREEN LED and am having trouble calculating the resistor needed. I believe that a green LED uses 3.3 volts and at 20ma,


    where do you get your 3.3 number? the chart i am looking at on the internets sez whites are in that range and greens are 2-2.3

    i can check out leds at work and see what the specs are.

    From here as well as other sources. Just curious which resistor I should use.

    https://www.petervis.com/electronics/led/led-resistor-calculator.html

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  • From Mortifis@VERT/EMPTYKEG to Vk3jed on Monday, December 10, 2018 10:38:57
    On 12-09-18 12:22, MRO wrote to Mortifis <=-

    @VIA: VERT/BBSESINF
    Re: Raspberry Pi GPIO
    By: Mortifis to All on Sun Dec 09 2018 01:38 pm

    pins, however, I need to wire a GREEN LED and am having trouble calculating the resistor needed. I believe that a green LED uses 3.3 volts and at 20ma,


    where do you get your 3.3 number? the chart i am looking at on the internets sez whites are in that range and greens are 2-2.3

    2-2.3 is more in line what what I remember as well. Certainly not 3.3.
    Yeah, white LEDs weren't around when I last studied this. :)

    From here as well as other sources. Just curious which resistor I should use.

    https://www.petervis.com/electronics/led/led-resistor-calculator.html

    ---
    þ Synchronet þ The Empty Keg BBS emptykeg.synchro.net:82 Lake Echo NS Canada
  • From Vk3jed@VERT/FREEWAY to Mortifis on Tuesday, December 11, 2018 07:00:00
    On 12-10-18 10:38, Mortifis wrote to Vk3jed <=-

    From here as well as other sources. Just curious which resistor I
    should use.

    https://www.petervis.com/electronics/led/led-resistor-calculator.html

    I happen to still agree with MRO, I think that site is wrong, but only for the green LED, the other values look reasonably accurate.


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  • From MRO@VERT/BBSESINF to Mortifis on Monday, December 10, 2018 21:15:21
    Re: Re: Raspberry Pi GPIO
    By: Mortifis to MRO on Mon Dec 10 2018 10:38 am

    where do you get your 3.3 number? the chart i am looking at on the internets sez whites are in that range and greens are 2-2.3

    i can check out leds at work and see what the specs are.

    From here as well as other sources. Just curious which resistor I should use.

    https://www.petervis.com/electronics/led/led-resistor-calculator.html



    i'm looking at digikey. there's a standard led here and the green one is spec'd at 2.1-2.6

    go on digikey and look up the datasheets
    it's important to know what you are working with
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  • From MRO@VERT/BBSESINF to Vk3jed on Monday, December 10, 2018 21:16:31
    Re: Re: Raspberry Pi GPIO
    By: Vk3jed to Mortifis on Tue Dec 11 2018 07:00 am

    On 12-10-18 10:38, Mortifis wrote to Vk3jed <=-

    From here as well as other sources. Just curious which resistor I should use.

    https://www.petervis.com/electronics/led/led-resistor-calculator.html

    I happen to still agree with MRO, I think that site is wrong, but only for the green LED, the other values look reasonably accurate.



    also COLOR is spelled wrong!

    *BLACKGUYPOINTINGATTEMPLE.PNG*
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  • From Mortifis@VERT/EMPTYKEG to MRO on Tuesday, December 11, 2018 10:49:56
    Re: Re: Raspberry Pi GPIO
    By: Vk3jed to Mortifis on Tue Dec 11 2018 07:00 am

    On 12-10-18 10:38, Mortifis wrote to Vk3jed <=-

    From here as well as other sources. Just curious
    which resistor I
    should use.

    https://www.petervis.com/electronics/led/led-
    resistor-calculator.htm
    l

    I happen to still agree with MRO, I think that site is
    wrong, but only
    for the green LED, the other values look reasonably
    accurate.



    also COLOR is spelled wrong!

    I went to an electronics supply/service outlet, the values on
    the site are accurate. COLOR vs COLOUR seems irrelevant lol

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  • From Mortifis@VERT/EMPTYKEG to MRO on Tuesday, December 11, 2018 10:51:33
    Re: Re: Raspberry Pi GPIO
    By: Mortifis to MRO on Mon Dec 10 2018 10:38 am

    where do you get your 3.3 number? the chart i am
    looking at on the
    internets sez whites are in that range and greens are
    2-2.3

    i can check out leds at work and see what the specs
    are.

    From here as well as other sources. Just curious which
    resistor I should
    use.

    https://www.petervis.com/electronics/led/led-resistor-
    calculator.html



    i'm looking at digikey. there's a standard led here and the
    green one is
    spec'd at 2.1-2.6

    go on digikey and look up the datasheets
    it's important to know what you are working with
    I agree that's why I posted the question, thank you for your
    responses

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  • From Mortifis@VERT/EMPTYKEG to Vk3jed on Tuesday, December 11, 2018 10:53:07
    On 12-10-18 10:38, Mortifis wrote to Vk3jed <=-

    From here as well as other sources. Just curious
    which resistor I
    should use.

    https://www.petervis.com/electronics/led/led-resistor-
    calculator.html

    I happen to still agree with MRO, I think that site is
    wrong, but only for
    the green LED, the other values look reasonably accurate.


    ... An aphrodisiac and a floor wax?
    --- MultiMail/Win v0.51
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    freeway.apana.org.au

    Thank you, I appreciate it, just wanted to clarify since I
    have seen conflicting values for green lads

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  • From Vk3jed@VERT/FREEWAY to MRO on Wednesday, December 12, 2018 07:50:00
    On 12-10-18 21:16, MRO wrote to Vk3jed <=-

    also COLOR is spelled wrong!

    Bloody Americans. :P


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  • From Vk3jed@VERT/FREEWAY to Mortifis on Wednesday, December 12, 2018 07:52:00
    On 12-11-18 10:53, Mortifis wrote to Vk3jed <=-

    Thank you, I appreciate it, just wanted to clarify since I
    have seen conflicting values for green lads

    You're welcome. Goes to show you can't trust everything you read on the Internet! :)


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  • From Vk3jed@VERT/FREEWAY to MRO on Wednesday, December 12, 2018 08:15:00
    On 12-10-18 21:15, MRO wrote to Mortifis <=-

    i'm looking at digikey. there's a standard led here and the green one
    is spec'd at 2.1-2.6

    Yep that makes sense.

    go on digikey and look up the datasheets
    it's important to know what you are working with

    Datasheets are the best source. :)


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  • From Jagossel@VERT/OUTWEST to Vk3jed on Tuesday, December 11, 2018 17:44:00
    Vk3jed, to Mortifis...

    ... Can anybody think of a good tagline I can steal?
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    Like that one above?

    -jag
    Code it, Script it, Automate it!

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  • From Vk3jed@VERT/FREEWAY to Jagossel on Wednesday, December 12, 2018 17:37:00
    On 12-11-18 17:44, Jagossel wrote to Vk3jed <=-

    @VIA: VERT/OUTWEST
    Vk3jed, to Mortifis...

    ... Can anybody think of a good tagline I can steal?
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    Like that one above?

    Hahaha, indeed. :D


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