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Topic: Using an external adapter to supply voltage to a rotary encoder. (Read 908 times) previous topic - next topic


Hello guys.

This is my first post here because Im relatively new to arduino and I just got mine last week.
So, I had and old rotary encoder that works in the range of 10-30V and I found an old nokia charger that delivers 8VDC and 720mA, Im using that charger/adapter as the voltage supply for the encoder and I've been checking the value of the outputs with my multimeter and it is around 6.8V so I made a standard voltage divider with 100Kohm as R1 and 270Kohm as R2. After that I checked the outputs with the multimeter and the output voltage is 4.66V (I think the arduino consider more than 2.5V as HIGH, is that right?) BUT I'm afraid to use that output in an arduino pin because I read every pin can handle only 40mA.

I've been very careful until now because I dont want to burn my arduino  :smiley-sweat:  so I want to know if it's safe to connect that output voltage to get the readings on the arduino or if I need something else to protect my arduino.

Also... is there any chance these resistors burn? (1/4Watt).

Thanks in advance.


The current limit only applies to outputs not inputs. The input current is negotiable because the input impedance is very high.


I think you meant negligible not negotiable, Mike. And no, there's no chance that the resistors will burn up, you'll only have a few micro amps flowing through them.






Yes dam automatic spell corrector on the iPad.

The art of getting good answers lies in asking good questions.


Don't tempt me. I'll never get to bed if I click on that link.

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