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Author Topic: 12v / Common Ground  (Read 1647 times)
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sorry guys can somebody let me know if this is ok?
cheers.


* 12v led_bb.jpg (82.53 KB, 968x743 - viewed 45 times.)
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The pin on the arduino can not provide enough current to drive a relay.

You need a transistor connected to either 5 or 12v, depending on what kind of relay you are using.

You will also need a diode so the relay won't "kick" the arduino's pin every time it releases again.



This is however not common ground.
« Last Edit: January 31, 2012, 05:58:05 am by bld » Logged

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Am I correct in thinking it would be enough to drive a solid state relay / Opto Isolator such as:
http://www.farnell.com/datasheets/40301.pdf

as I would like to keep the part count down to a minimum.

Also can I confirm that the Arduino ground is ok to be connected to the 12v ground?

 
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'Yes', to the solid-state relay

'Yes', to the common ground

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I want to add that the circuit/load getting switched may or may not share the ground (IOW, it could be "isolated").
« Last Edit: January 31, 2012, 07:45:30 am by runaway_pancake » Logged

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Why are you using a relay?  The load is a single LED - is that the final intention or do you have a larger load in mind?

Most LEDs melt/explode if you put 12V across them - did you mean to have a current-limiting resistor?
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It will be a ~3 - 5w led dependent on tests
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If you use a MOSFET you can use PWM...

You will need series resistor (and a heatsink for the LED).
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It will be a ~3 - 5w led dependent on tests

You can drive a 5W LED straight through a MOSFET transistor, no relay needed.

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