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Topic: Optocoupler for PC fan with same 12v feed to arduino? (Read 656 times) previous topic - next topic

diecastblue

I am wanting to control a PC fan with arduino, looking at http://www.uchobby.com/index.php/2007/09/23/arduino-temperature-controlled-pc-fan/
Thing is, the 12v that is powering the motors will be the same 12v that is going into my Arduino VIN pin to power it. Is the Optocoupler actually going to protect anything?
What is the Optocoupler actually protecting against?

MichaelMeissner

The optocoupler is preventing the 12v that the fan uses from being fed back into the Arduino.  As I understand it, the VIN pin will have 12v, but all other pins on the Arduino can only deal with at most 5v coming in.  You can also use an optocoupler when the output side doesn't share a power source or ground with the Arduino side.

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