Diode to Temperature Sensor
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- Опубликовано: 11 сен 2024
- Anything that has a PN junction you can turn into a temperature sensor. Some diodes or devices have junctions with different forward voltage drops like zener diodes.
Original Code and Page: www.hackster.i...
My Code: drive.google.c...
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CORRECTION: At 9:24 I said "divide" when I meant "multiply"
also
first.
12:08
Just write difference * (1/2.2)
ll constants are calculated during compile time, turning it into 0.4545 makes it easier for anyone reading the code why 0.45454 was chosen. It also makes it easier to change the constant to 1/2.1 or 1/2.3 if that is ever needed.
You are posting such good content! I can tell this channel is going to blow up soon.
The calculations here assume that the diodes resistance is related to its temperature in a linear fashion.
To verify this you will need to calibrate it by taking a reading while it is in an ice/water bath (0 deg celcius) and again when it is immersed in boiling water (100 deg C).
You got the 'resistance vs temperature' of the diode backwards - heating up a diode would make it conduct more, cooling it makes it conduct less.
You are right! I might have to take down this video and insert a better explanation. While heat does cause more resistance in a regular conductor, in a PN junction you are actually giving energy to free up/allow more electrons to flow via heat and making it easier for those electrons to pass through the PN junction. Thus the forward voltage drop lowers because if its easier for electrons to pass the PN junction, theres less of a difference in potential (voltage) across the junction. Let me know if thats a good explanation or not, and thank you for pointing this out.
@@SciCynicalInventing I think this is a good explanation. Usualy you would use the PN junction as a thermometer with a constant current through it and that would make it even more obvious (and is done to have a constant junction voltage vs temperature law) - current stays the same but 'resistance' lowers with rising temperature - the junction forward voltage falls. 😉
Dude, great video. Making temperature sensors from cheap scraps is great. I have been using Arduinos and Pis for years but I didn't know diodes could sense temperature. Keep posting! Now I want to try doing it with LEDs.
or you can make a current mirror with a diode , and then conect diode to adc , to measure voltage drop
You could've unplugged your fan man...