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Greenonline
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As soon as I unplug my Arduino from USB and only use the VIN pin with my 9V9 V power supply, the analog readings from my arduinoArduino start to get unstable, which means the value fluctuates much more than with USB connected. When I reconnect USB again, the readings are stable again.

I'm trying to build a load scale using a load cell, an INA125P and the Arduino, using this setup here: https://learn.adafruit.com/smart-cocktail-shaker/calibrationInstrument Amplifier Calibration Therefore.

Therefore I need stable readings. For example, I wrote some code to convert the analogRead()analogRead() value to grams. While USB and VIN (9V9 V) connected, I get a stable reading of about 8.3 to 8.7 grams when I put a weight of 8.5 grams on the scale. As soon as I unplug USB, the LCD shows values from 7.8 grams up to 9 grams.

Unfortunately, I don't have any other power supply which I could use to test. I've already tried to use a 9V9 V battery with the same results. Do I maybe need some additional de-coupling capacitors?

Thanks in advance.

As soon as I unplug my Arduino from USB and only use the VIN pin with my 9V power supply, the analog readings from my arduino start to get unstable, which means the value fluctuates much more than with USB connected. When I reconnect USB again, the readings are stable again.

I'm trying to build a load scale using a load cell, an INA125P and the Arduino, using this setup here: https://learn.adafruit.com/smart-cocktail-shaker/calibration Therefore I need stable readings. For example, I wrote some code to convert the analogRead() value to grams. While USB and VIN (9V) connected, I get a stable reading of about 8.3 to 8.7 grams when I put a weight of 8.5 grams on the scale. As soon as I unplug USB, the LCD shows values from 7.8 grams up to 9 grams.

Unfortunately, I don't have any other power supply which I could use to test. I've already tried to use a 9V battery with the same results. Do I maybe need some additional de-coupling capacitors?

Thanks in advance.

As soon as I unplug my Arduino from USB and only use the VIN pin with my 9 V power supply, the analog readings from my Arduino start to get unstable, which means the value fluctuates much more than with USB connected. When I reconnect USB again, the readings are stable again.

I'm trying to build a load scale using a load cell, an INA125P and the Arduino, using this setup here: Instrument Amplifier Calibration.

Therefore I need stable readings. For example, I wrote some code to convert the analogRead() value to grams. While USB and VIN (9 V) connected, I get a stable reading of about 8.3 to 8.7 grams when I put a weight of 8.5 grams on the scale. As soon as I unplug USB, the LCD shows values from 7.8 grams up to 9 grams.

Unfortunately, I don't have any other power supply which I could use to test. I've already tried to use a 9 V battery with the same results. Do I maybe need some additional de-coupling capacitors?

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edit approved Mar 16, 2015 at 13:28
Paolo Zanchi
edit approved Mar 16, 2015 at 13:28
Paolo Zanchi
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user1320304
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Arduino unstable analog reading when using power supply

As soon as I unplug my Arduino from USB and only use the VIN pin with my 9V power supply, the analog readings from my arduino start to get unstable, which means the value fluctuates much more than with USB connected. When I reconnect USB again, the readings are stable again.

I'm trying to build a load scale using a load cell, an INA125P and the Arduino, using this setup here: https://learn.adafruit.com/smart-cocktail-shaker/calibration Therefore I need stable readings. For example, I wrote some code to convert the analogRead() value to grams. While USB and VIN (9V) connected, I get a stable reading of about 8.3 to 8.7 grams when I put a weight of 8.5 grams on the scale. As soon as I unplug USB, the LCD shows values from 7.8 grams up to 9 grams.

Unfortunately, I don't have any other power supply which I could use to test. I've already tried to use a 9V battery with the same results. Do I maybe need some additional de-coupling capacitors?

Thanks in advance.