Project 03 - What's happening when I don't connect temp sensor to ground?

Official Hardware Kits Starter Kit
1

Hi all. I'm very new to Arduino and electronics so this is a very basic question.

I've just been working through project 3 which I've got working nicely. However, on my first try I forgot to connect the temperature sensor to the ground. This caused quite erratic readings and basically reported a random voltage somewhere between 4 and 5 volts and therefore a completely incorrect temperature.

Can anyone explain what's actually happening when I don't connect the sensor the ground please? My assumption is that the sensor wouldn't report anything since the circuit isn't complete and therefore no power is going through the sensor.

Here's a sketch of the missing piece:

IMG_5543
IMG_55431280×828 26.6 KB

2

A0 is gonna float because the sensor circuit is open and there is no input. When you read an analog pin that is floating without input the result is random.

3

Thanks for the speedy reply! I see. So it's the same as if I tried reading A0 without anything plugged in?

4

Yes

5

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.