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Author Topic: 250mA from an Arduino Pin  (Read 726 times)
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Manchester (England England)
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Well I have done some tests and found that I can get over 250mA from an output pin of an Arduino.

Of course this will / has damaged my Arduino but it is still actually working. I did this to to investigate what sort of currents are being drawn by connecting an LED direct without a resistor. This followed some recent discussions on this forum.

I have added an LED page to my Tutorials:-
http://www.thebox.myzen.co.uk/Tutorial/LEDs.html
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Seattle, USA
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Grumpy Mike,

You seem very far from grumpy in your generous sharing of extensive knowledge.

Your site has lots of good explanatory info on it -- an RSS feed for newly added items would be great, in case one misses a thread here about it.

Thanks lots for all of it.

.andy
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.andy

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That made me realize that I should probably use a resistor with an opto-isolator as well, right? Somehow I missed that before, even I knew that I should use resistors with LEDs and the other half an opto-isolator is a LED.

For some reason the circuit and Arduino Nano still seem to work after few months, but I don't want to push my luck any futher.

I checked the opto's (sharp pc817) datasheet. I am not sure if I got the terms right, but the parameters I used to calculate the resistor value was the typical forward voltage 1.2V @ 20mA (max rating for the forward current is 50mA). That led to resistor value (5V-1.2V)/0.02A = 190ohm. 220ohm is closest I have. Does that sound reasonable?

Btw, this might be a silly question but here it comes anyhow: It doesn't matter which side (anode or cathode) of the LED the resistor is, does it?
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Halifax, NS, Canada
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Like Andy Davidson said, thanks for all the info you share on here.  I've learned lots from your posts alone!
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Halifax, NS, Canada
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oh and this is the best quote imo

"Does my Arduino still work after this? Yes it does! Have I permanently damaged it? You bet I have!"

lol
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Manchester (England England)
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It doesn't matter which side (anode or cathode) of the LED the resistor is, does it?

No problem the electrons don't care what they see first.

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= 190ohm. 220ohm is closest I have. Does that sound reasonable?
Yes it does, spot on.   smiley

However, have you not got a 180R resistor, that is a standard value? Anyway it doesn't matter.

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RSS feed for newly added items would be great
Good idea but I am not sure if my ISP supports it, I will have to check.
« Last Edit: October 20, 2009, 05:31:39 pm by Grumpy_Mike » Logged

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