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Topic: 2v output on arduino (Read 1 time) previous topic - next topic


If the coil resistance is 320ohm and the pin only pulls up to 2V the chip is fried. Probably destroyed by inductive kickback if there was no diode.
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i check the voltage coming out of the pin at 5v when it is on, but once i connect it to the relay and check voltage again its only 2v and my relay needs 5v to switch. the relay has already got a diode in parallel with the coil for protection so chip isn't fried.


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The built-in pull-ups are spec'd as between 20k and 50k, the relay is alleged to be 320 ohms, there's no way that makes a potential divider of 40%!

If the load on the pin is really 320 ohms then the chip is fried since it would produce about 4.5V into that load.

A good measurement to make would be the current into the relay winding when directly connected to 5V supply.  If it reads about 15mA then it is 320 ohms and the output pin is blown (assuming no other load on the pin). 
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