pots wired in parallel

Hi,
My project is working fine but I was just curious about something. I plugged in a 10K pot by itself into my arduino and used analogRead and got values 0 - 1023, like I expected. I then plugged in a 5K pot by itself and used analogRead, and got values 0 - 681, which I expected to be different than the 10K values. Then, I plugged in both the 10K and the 5K pot, sharing the same 5V and ground pins, but using their own analog in pins (A0 and A1). The result: Both pots work fine independently, but analogRead now reports the full range of 0-1023 for both of them, as opposed to 0-681 for the 5K pot like I was expecting. Why?

Sounds like when you hooked up the 5K by itself it was wired incorrectly. Both should read 0 at 0V and 1023 at 5V.

opposed to 0-681 for the 5K pot like I was expecting.

Why were you expecting this result? It is wrong if there is only the pot in the circuit.

Did you plug in the 5K pot into 3.3V by mistake?

liudr:
Did you plug in the 5K pot into 3.3V by mistake?

Yep. 0 - 681 sounds suspiciously like 0-3.3V.

liudr:
Did you plug in the 5K pot into 3.3V by mistake?

Why ask, its clearly what happened!

MarkT:

liudr:
Did you plug in the 5K pot into 3.3V by mistake?

Why ask, its clearly what happened!

I am a teacher. This is how we intimidate students, asking the obvious. It's working (oh we feel good about it):slight_smile:

That must have been it, thank you!

No problem. Any pot should go between 0 and 1023, regardless of their total resistive values. A pot simply splits the 5V into two voltages, depending on where the wiper (center tap) is located. Larger resistance values consume less power but also comes with higher impedance and capacitance. I'd be happy to use any value between 1K and 100K for a control knob.