I have rebuilt our Tefal Raclette, so it is now smart integrated via ESPHome, I did that last year.
Now I wondered if I could add a sensor for temperature measurement.
It gets very hot, it is a frying pan, and the metal bar that heats up the frying pan gets glowing red.
I would like to place the sensor so it measures the frying pan, but of course not the glowing metal bar that heats it.
What sensor can I use for that, that works with ESPHome?
Something like this? https://www.banggood.com/-50300C-PT100-Temperature-Sensor-Probe-2-Wire-Type-3-Wire-Type-650mm-Thermocouple-Thermal-Resistance-with-1m-Silicone-Cable-p-1538550.html?cur_warehouse=CN&ID=6267083&rmmds=search
And then the NTC interfafce, or ?? I have no idea what I’m doing here Nick 
Or a MAX6675 might be better?
Hi @nickrout
Ok, so the max6675 is now ordered, and I looked at my current code. I’m not sure I can make it work with the current setup.
I have very little space to work with in the device, so I’ve placed an esp01 chip in a dual relay board in it.
This uses 1 relay for the 5V led light in the button, and 1 relay for the 220v for the device itself.
The relays are handled by UART writes.
The esp01 doesn’t give me many pins to work with, and the max6675 uses spi which requires 3 pins +3,3v and gnd. The last two are available of course, but the uart uses the rx and tx pins:
uart:
baud_rate: 115200 # speed to STC15L101EW
tx_pin: GPIO1
rx_pin: GPIO3
and looking at the esp01 I seem to have only two pins I can use:
So if I am to get this to work, I guess I need to wire in a d1mini instead of the esp01? and then I’m running out of space I think.
Hmmm, or maybe replace the entire relay board and esp01 with a simple twin relay board and a d1mini…, or can I remove the RX pin from the uart config, and repurpose that for spi? And then I need to handle using GPIO0 for output somehow (adding a 3K3 resistor to vcc to pull it high???) I have no idea if that is right.
Yeah that is over my pay grade. I guess you can try various combos, but beyond that I don’t know.
ESP-01 doesn’t break out SPI bus, so unless you want to solder directly to the ESP8266 chip, then yep, a D1 Mini is what you need. Not much bigger than the ESP-01, actually less tall, and has built in voltage regulation.
Hi Nick, do you know if a similar chip to the max6675 that has a better temperature resolution than 0.25 C, ideally a 0.1 C resolution? Thanks!
I got it set up btw. I also made a video about it.
So now our raclette has a timer for turning it off automatically after two hours, and also measures the temperature with the 6675.
I’m considering adding an extra led to make it show different colours depending on the temperature.
Mounting the sensor was a bit of a journey, found a pipe with external threads, made a hole in the plate below the pan, and put a nut on top and below, found a spring to make it push against the plate from below, and a piece of cabonpipe to make the spring fit the distance.
It works very nicely, and measures the pan nicely.
I also made an endplate for it in my 3D printer, it’s made with PETG as PLA started to warp.
I think I’ve seen that, but can’t find it now.
I’m showing the final version here: ESPHome projekter - nogen gange går det galt - YouTube
The only change from that is that I’ve reprinted the small cover plate in petg to heighten temperature resistance.
I also made one here were I go through the setup a bit more: Raclette V2 - Smartificeret - YouTube