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Proper LED Circuit
#1
Posted 01 December 2010 - 01:45 AM
#2
Posted 01 December 2010 - 02:32 AM
I have heard, there has to be a certain way I should wire an LED (10mm 3.5-4.0v) to the Netduino safely. If someone could help me picture what I have to put together that would be great!
-Cwbh
I've hooked up one of those straight into 3.3V and an OutputPort, but I've also heard that this isn't suggested so I'll attach a schematic of what is (I'm 90% sure) a 'safe' way to do it. I personally think that unless you got a bunch of LEDs you don't have to use transistors, but I could be wrong.... I guess until you hear from Chris or another member that knows a lot about this stuff then its best to stay on the safe side?
Attached Files
#3
Posted 01 December 2010 - 11:49 AM
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#4
Posted 01 December 2010 - 12:58 PM
#5
Posted 01 December 2010 - 02:32 PM
![Posted Image](http://www.stopreinventingthewheel.com/srtw/images/netduino/forumhelp/simple-led-transistor.png)
I would use a 1k transistor to the base, which (using V=IR) works out to a safe 3.3ma (I=V/R, or IB = 3.3v/1000, which is .0033 amps, which is 3.3ma) current from the netduino pin, and a 220k resistor for the LED load, limiting the current to 15ma (IC = 3.3v/220) which should be safe for most leds, but possibly a little dim. (Check your LED specs)
#6
Posted 01 December 2010 - 02:36 PM
Today LED's, tomorrow, the world!!! Well, OK, maybe servos.
#7
Posted 01 December 2010 - 02:41 PM
#8
Posted 01 December 2010 - 02:44 PM
#9
Posted 01 December 2010 - 02:54 PM
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Today LED's, tomorrow, the world!!! Well, OK, maybe servos.
#10
Posted 01 December 2010 - 03:08 PM
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Follow me on Twitter! | Find me in irc.aurora-irc.eu #aniboshi [often but not always] | Also known as ntkrpamp on IRC channels | I don't post here much but I visit often.
#11
Posted 01 December 2010 - 03:52 PM
I just attach LEDs to a digital i/o and then a ground pin, but I still need to get a breadboard. Maybe that's not the way with a 10mm one.
You're probably "ok" doing this, but not too many LEDs draw less than 8ma, so you are theoretically risking running outside of the specs and burning out your netduino, if you are using one of the 8ma or 16ma pins. You should probably use some kind of resistor, regardless.
#12
Posted 01 December 2010 - 04:33 PM
#13
Posted 01 December 2010 - 05:21 PM
#14
Posted 01 December 2010 - 06:39 PM
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#15
Posted 01 December 2010 - 07:30 PM
From: http://www.kpsec.fre...om/trancirc.htm
![Posted Image](http://www.kpsec.freeuk.com/images/trswipnp.gif)
#16
Posted 01 December 2010 - 08:58 PM
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