Voltage measuring

[Fhjfhfjhfjhfjhfjhfjhfj]

I’m doing the “dealing with diabetes” project but when I measure the voltage of the conductivity sensor in the distilled and tap water they both come out to 5.07 which I know is above what it is supposed to be. Along with that, the voltage readings shouldn’t both be the same. Is there something wrong with my project? The attached file is what my project looks like so far in case it is an issue with that.

[Administrator note: project URL: https://www.sciencebuddies.org/science- ... l-pancreas ]

[bfinio]

Hi - it's a little hard for me to tell since this is a zoomed-out picture showing the whole setup, but it looks like you have some mistakes on your breadboard. Look carefully at Figure 6 in the project:

https://www.sciencebuddies.org/science- ... l-pancreas

Notice how the "top" end of the resistor is in its own row on the breadbaord, which is connected to the power bus with a jumper wire. The "bottom" end of the resistor is in a different row, which is connected to both the Arduino A0 pin and one end of the conductivity sensor. That is the row where you'd want to connect the positive probe of your multimeter to measure the voltage across the conductivity sensor. The other end of the conductivity sensor is then connected to the ground bus, which is where you should connect the negative probe of your multimeter.

Again, it's a little hard for me to see in the photo, but it doesn't look like that's how you have things wired. It looks like you have the "top" end of the resistor connected to both A0 and the power bus, and that's where you also have your multimeter's red probe connected - which means you're always going to measure about 5V (since it's connected to the power bus), and that's consistent with your observations.

I would carefully re-check how you have that part of the circuit wired correctly. If you have trouble, then you can post a close-up picture of just your breadboard and we can provide further assistance.