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Comfort 9: Is It Too Hot

Differential ADC + Heating Pad

This week I decided to make a very lowkey version of what my final project would be. It testing the "hand warmer" part of the heat faxer - heating an object and shutting off the heater once the desired temperature is achieved.

Last week I was recommeded to try Differential ADC for measuring temperature (also use NTC). For a future reference, differential ADC means: A differential ADC (Analog-to-Digital Converter) resistor typically refers to the resistors used in a differential ADC circuit, where the ADC measures the difference between two input signals

The issue was ESP32C3 cannot read Differential ADC directly, and at office hour Anthony helped me to come up with a few options:
1. IR Camera to measure IR
2. Differential ADC with a breakout board with a different microcontroller
3. Differential ADC + ESP32C3 with an extra component (Op amp)

Anthony suggested ADC would be the most reliable, so he helped me to understand how differential ADC would play out in a schematic diagram. The diamond diagram in the picture is called "wheatstone."

With the op-amp option, this is the part that will be attached after the wheatstone to make the measurement more readable.

This is how the schematic looked like after all the op-amp + differential ADC + heating pad were added to the schematic diagram.

Quentin suggested to add Mosfet to the heating pad.

I had a bit of issue trying to figure out how to put wires for PCB design. Quentin also helped with figuring out how to connect things without having to make wires go on the other side of the board.
I played around with the wires and put it on a circle shape to match the shape of the heating pads.

PNG files for milling

The milling went quite smoothly. Definitely getting much better + faster at it.

I gathered all the parts except mosfet and heating pad (that was delivered today (11/5))

Unfortunately as I was soldering, I ran into MAJOR soldering crisis as I was trying to solder an op amp. It was too small and the copper part ripped off as I was trying to remove the soldered parts.
To be continued with:
- updates on soldering an op amp
- updates on getting right results from differential ADC
- updates on adding a heating pad

Anthony helped me to figure out the issues with soldering op amp - using better soldering wire. I think I just got better at soldering afterwards as well.
I also was able to test if the heating pad was working, and it was working once it was plugged to the power supply.