user38304: I have made a simple temp sensing circuit that lights an LED when it reaches a certain point. It works perfectly when powered by a USB plugged in to the laptop but when I connect it to a 5V supply with a mini-USB connection nothing happens.
Is this correct and do I need to send power directly to the board on the 5V pin?
Many thanks,
Jack

user38304: Thanks all. I found a different power source with a mini-usb connector and it works fine. I think when plugging it in to the PC the Nano makes some faint clicking noises but when direct to  5v plug it does not? I'm not sure so I'll re-test. It was the lack of clicking that lead me to believe it wasn't working as I can't see the on board LEDs using my enclosure.
I don't know about the accuracy but it seems to work for my situation - it is to be placed in a fridge that recently turned itself in to a freezer but has since fixed itself. This project is an early warning system in case it decides to do it again.
Thanks again.
Jack

38304: <p>I have made a <a href="http://hackscience.io/project/temperature-alert/" rel="nofollow noreferrer">simple temp sensing circuit that lights an LED</a> when it reaches a certain point. It works perfectly when powered by a USB plugged in to the laptop but when I connect it to a 5V supply with a mini-USB connection nothing happens.</p>

<p>Is this correct and do I need to send power directly to the board on the 5V pin?</p>

<p>Many thanks,
Jack</p>
 38304: <p>Thanks all. I found a different power source with a mini-usb connector and it works fine. I think when plugging it in to the PC the Nano makes some faint clicking noises but when direct to  5v plug it does not? I'm not sure so I'll re-test. It was the lack of clicking that lead me to believe it wasn't working as I can't see the on board LEDs using my enclosure.</p>

<p>I don't know about the accuracy but it seems to work for my situation - it is to be placed in a fridge that recently turned itself in to a freezer but has since fixed itself. This project is an early warning system in case it decides to do it again.</p>

<p>Thanks again.
Jack</p>
