External ambient temperature.

5 x Dual MOSFET Driver DC 5V-36V PWM Regulator 15A 400W Module MOS FET (E120) Completed
https://i.ebayimg.com/images/g/UbIAAOSwv81kHORO/s-l1600.jpg

This kind of thing interests me too although I'm not very good at it

Back in the 80's, I worked in a research lab and made several heat stimulators for physiological experiments. The temperature sensing side of things used either a thermistor or, better, a thermocouple. The signal was amplified to 1degC/Volt and displayed on a digital voltmeter. We built it all with op-amps and discreet components but I'm sure that there would be an Arduino circuit that would cover this, no?

Mind you, I bet you could buy a device that does exactly this from Amazon/eBay for a few quid. Not so much fun though.

The fun can start when you daisy chain several of these together. Our motor caravan has the toilet light switch in a stupid place so I fitted a PIR with timer. This is fine but a bit of a shock to have the full brightness in the middle of the night, so module two subdues the lighting at night & module three enabled the entire system only when it is dark.
The toilet lights at church are forever being left on, they have now been modified again with PIR units. Apart from it being cost effective it was fun but if you’re working on anything electrical ISOLATE the circuit.
With a bit of imagination the world could be your oyster, if you haven’t, it’s a lobster, but there again I’m not a fan of shell fish or crustacean.
M

Hi All, Apologies for the radio silence. The France trip was not a really a holiday but more one about elderly in laws and their health, which is ongoing…..So due to that there’s not been any further movement on the thread title project. Hopefully I’ll be able to get it moving soon, and it’ll be done for when the weather cools down.
Regards,
Michael.