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Topic: wall wart vs USB/9V battery (Read 887 times) previous topic - next topic

zeus2kx

Hello,

Why does the analog sensor (lets say a 5V temperature sensor) value differ when powering Arduino with a wall wart/USB/9V battery?
With all these three power sources I receive different values.

Thanks.

Best,

Z

JimboZA

Perhaps the temperature changed in the time it took you to switch the power. Are you comparing the temperature you read against a known value?
"Could you do the egg bacon spam and sausage without the spam then? "

No PMs for help please.
DO NOT power servos from Arduino 5V: give them their own power and connect the grounds.

zeus2kx

No temperature didn't change. I know temperature is constant since I am trying to calibrate.
Using wall wart I see almost correct results, 23C but with USB, it shows 40-42C and 9V battery shows 26-27C.

I didn't just notice these differences with only temperature sensor but also with gas sensors.
I am wondering what is the issue here.

JimboZA

Wow, 23 vs 40+ is kinda drastic....

Maybe you need to check that the voltage supplied from the Arduino 5v is actually 5v under all three situations?

Are you using the 5v pin?- not accidentally using the Vin pin which at least in the case of the 9v battery would be 9v... wouldn't explain the usb problem tho
"Could you do the egg bacon spam and sausage without the spam then? "

No PMs for help please.
DO NOT power servos from Arduino 5V: give them their own power and connect the grounds.

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