(Part 2) Best temperature probes & sensors according to redditors

I've actually done what you're asking for with a chest freezer. I bought a PID thermostat, like this.

Then I replaced the thermostat in the fridge with the PID thermostat, that thermostat had a chiller output and a heater output (and heater could be configured to use the internal relay so I didn't need to use a second SSR). I connected the chiller to the compressor and the heater relay to an outlet box. The heater was just a reptile heating pad I plugged into the box and threw into the fridge, but that was a little on the low power end, I'd probably use a ceramic heater if I had to do it again. Also, all the PID controllers seem to be sold with a K-probe, those are no good, they don't measure below 0C, and the thermostat needs swing, so I needed to keep the set point over 2C to get it to work (which is not terrible). I ended up buying a PT100 probe which works well.

I have a Johnson Control A419 I've been using for similar purposes for about three years now and it's worked great!

I have heard horror stories of similar control units failing and causing either a continuously open or closed circuit. If you have a working thermostat in the freezer, it might help to set it to its highest temperature, which should still be well below the new control unit's setpoint but hopefully above freezing to prevent catastrophic freezing if the unit breaks in the open state.

If it breaks closed, the temperature in a unit like this can rise very high -- I had a similar thing happen when I had a compressor failure -- due to the circulation fans running continuously. If it's cold in the the garage where it is, this would likely be fine, but in the summer it could be a big issue. I have one of these to monitor the temperature and push notifications if the temperature or humidity leave the bounds I've set. So far it's worked great and the app is very easy to use, except that I needed a WiFi range extender to ensure coverage while it's inside the fridge.

Also, super sick fridge!


EDIT: IF this is a used unit and you haven't already, REPLACE THE CLIPS THAT HOLD UP THE SHELVING! They can fail, which is catastrophic, and they're like two dollar a piece. Installed correctly, they should last for years but there's no reason not to replace them if you don't know their usage history.

Just a rough estimate. It it was around $250.
I had already had the case, 1 pid, two Switches, the Keyes switch and 3 LEDs.

Switches ($7 x2)

LEDs ($6 x4 two reds 12v and two yellows 110v)

PIDs ($24 x2)

Temperature Probes ($15)

Power Plugs ($12)

Power Plug ($19)

Element Plugs ($20)

Element Plugs ($8 x2)

Temperature Plugs ($12)

Temperature Plugs ($12)

Terminal Strips ($11)

The above list is $203.

Miscellaneous other wires, the key switch and a electrical plug for the pumps.

And I bought some new tools, including a knockout punch set from Harbor Freight.

I have that same thermowell, there are a ton of sensors that are 1/4 inch or less that fit in it. Both the STC temperature probe, the johnson digital/analog temp probe fit in it if you want a controller with probe.

If you're just looking for probes, here are some. You don't need it to be snug in there, touching the bottom/inside of the thermowell is enough in my experience.

.236"

.2"

.2" - 5 Pack

The thermowell fit perfectly in a 3/8 inch bore, it has a flanged head so it rests nicely without falling through.

My tip for long term cooler use: get a Bluetooth temperature and humidity logger ... or the waterproof temperature only one to keep in the bag, and then you'll know if your food stays in the safe range.

I'm missing links for the buttons, RGB light, power supply, converter and the relay

Induction heater:
LM YN ZVS Driver Board ZVS Induction Heating Circuit DC12-30V Zero Voltage Switch Power Supply Driver Board https://www.amazon.com/dp/B075G9NPWW/ref=cm_sw_r_cp_apap_NQzxD1dqaaJyw

Arduino nano:
HWAYEH For Arduino Nano V3.0... https://www.amazon.com/dp/B07D5B3ZGX?ref=yo_pop_ma_swf

Touchless temp sensor:
HiLetgo GY-906 MLX90614ESF... https://www.amazon.com/dp/B071VF2RWM?ref=yo_pop_ma_swf

You'll need one of these too: High Temperature k-type Thermocouple Sensor Ceramic Kiln Furnace with connector plate and hook up cable 2372F 1300C CR-06 https://www.amazon.com/dp/B0713X6XG3/ref=cm_sw_r_cp_apa_i_7s02CbP79A075

Thanks! Yes, the plan is to mount two thermocouples in the body of the pan that are removable. The bottom of the lid is lined with aluminum sheet metal. The wood is not treated :) check out the other gallery's under my imgur account.

I'll be using two of these https://www.amazon.com/dp/B06XSX1K5Q/ref=cm_sw_r_cp_apa_i_VtgXDbRZ7HVQM

Here you go

https://www.amazon.com/Thermaltake-Pacific-Liquid-Cooling-Temperature/dp/B06XYHLYYZ/ref=sr_1_fkmrnull_2?crid=1NJEALR0XUMWZ&keywords=thermaltake+temp+sensor&qid=1555675788&s=gateway&sprefix=thermaltake+temp%2Caps%2C148&sr=8-2-fkmrnull

I want to use them to check the temperature of my propane forge, the steel and use them to test the temperature of steel when I am trying to air harden it correctly for D2 steel. Blacksmithing Pyrometer stuff

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https://www.amazon.com/Temperature-Thermocouple-Ceramic-Connector-CR-07-x/dp/B0711BKPJG

or

https://www.amazon.com/pyrometer-Annealing-Thermometer-Thermocouple-Fahrenheit/dp/B01DMQOWD4

For the sensor breakout, you need 3-ish things:

The PCB, An RJ-11 or RJ-45 jack (the same as the mentioned in the PCB for the ESP8266), and 1-3x Temperature Sensors

For the temp sensors, you can get them on Amazon, eBay, or AliExpress - from my experience, all 3 are about the same price.

Here’s a sample AliExpress seller
...and a sample seller on Amazon

Besides the above you can also get an optional door sensor, but I don’t use them in any of my builds so I don’t have a recommendation. You can always add it later also, if you wish.

I am using cheap as !@#$ DS18B20 sensors, a few pages of home written python, and cron. at the sensors, cron fires one python script every minute that reads and broadcast the sensors. It also writes the temperature to a file on the pi. Every five minutes, cron fires a python script that reads the local temperature file and writes it to a queue file (Open queue file, write-append, & close). It then re-opens the queue file and tries to send the data to the remote database. If it succeeds, it truncates the queue file, of it fails it simply exits. This way if the server is unreachable, it locally logs the data until the server comes back online. The display unit uses the the official Raspberry Pi 7" touch panel. The display is really nothing more than a Chromium browser set to autolaunch in kiosk mode. The display itself is HTML, PHP, and Javascript. The Pi driving the display also hosts Apache, so it hosts the web server as well as the web browser. This allows mwe to access the panel from any web browser inside and outside my home. When I ask for a chart it sends a HTML request to the ODroid that also runs PHP. I use JPGraph to create a jpeg chart which is used as the background image for the screen.

I created a custom circuit board to handle the garage door. It has two tiny relays and the restor networks that can read up to 6 read relays. These boards are the exact same size as the Raspberry Pi Zero.

Word. I might wait till like 1-2 before you plan on flipping to 12/12. For humidity I started spraying the walls of my tent periodically. Also small a humidifier might be worth looking into. Could even do a fairly cheap climate control system hooking up a IFTTT sensor to smart switches connected the humidifier.

I've been looking into getting something like this for my setup.

Make a dual op amp proportional PWM controller for temperature control.

The first op amp is the P function with set point using a lm35 temp sensor.


The second op amp is a square wave generator as a PWM function. The P function ties in to positive input of the square wave generator to get PWM. The output goes to a transistor driving a fan.

Adjust the gain just to the point of system oscillation, cut the gain in half, and you'll have a pretty effective and simple temperature controller.

Here's one for $20 on Amazon that measures from -200°C to +260°C.

I google cryogenic thermocouples

I have an inground pool and have been wanting to set up something like you mentioned in the skimmer, though I've wanted to add a temperature sensor as well (for "pools ready to swim in!" notifications). My rough plan is to use something like this https://www.adafruit.com/product/464 and a DS18B20 temperature sensor https://www.amazon.com/Hilitchi-DS18B20-Waterproof-Temperature-Sensors/dp/B01AJALC5M/ combined with a battery powered ESP8266. I haven't actually started an attempt but I'd love to hear other ideas.

Edit: I saw this video in another post, might fit the bill https://youtu.be/0zUp7Dia4l4

BEAUTIFUL lid. i really wish i had that. the only other thing i'd recomend is a rigid type k thermo couple, and a small hole drilled in your lid so you can consistently place it.

are you not worried about the wood burning/browning? when i was using some wood blocks to sit on top, they did brown a bit. i don't know if they are offgassing anything bad. if the wood was treated with anything.

https://www.amazon.com/Uxcell-a15063000ux0338-Stainless-Temperature-Thermocouple/dp/B017LB3BQA/ref=sr_1_5?keywords=type+k+thermocouple+probe&qid=1573149067&sr=8-5

it's long enough that it should be able to reach down near the bottom. place it near a corner so it's much less likely to get hit by the bread paddle. it will likely be longer than you need, but just have it sit on a wood block, like your exhaust stopper, until it rests at the right depth.

this is a very inexpensive thermocouple reader
https://www.amazon.com/Proster-Thermocouple-Thermometer-Dual-Channel-Thermocouples/dp/B071V7T6TZ/ref=sr_1_4?keywords=thermocouple+reader&qid=1573149233&sr=8-4

but the temp probe i linked, doesn't have the right connector to plug into this unit. you need the yellow connector like this, but i don't know if it's long enough

https://www.amazon.com/PerfectPrime-TL1815-HeadProbe-Thermocouple-Temperature/dp/B0142S9J4S/ref=sr_1_3?keywords=type+k+thermocouple+probe&qid=1573149211&sr=8-3

grab one of these put it in the middle of a small extension cord, now you set it to switch off when it is above whatever temperature you want, tape the probe to your crocpot and there you go, you can even use alexa to turn it on/off or whatnot. https://smile.amazon.com/Sonoff-DS18B20-Waterproof-Temperature-Automation/dp/B07F34DF2T/ref=pd_sbs_60_3/141-8559732-8283042?_encoding=UTF8&pd_rd_i=B07F34DF2T&pd_rd_r=ec7c3acc-742f-11e9-a650-71be33d71435&pd_rd_w=YXglp&pd_rd_wg=907jB&pf_rd_p=588939de-d3f8-42f1-a3d8-d556eae5797d&pf_rd_r=RHFJM4BVKD01TR3CHDZV&psc=1&refRID=RHFJM4BVKD01TR3CHDZV

I use a nodemcu board, based on the esp8266, and treat it just like a wireless enabled arduino. And then I used a bme820 to measure temp/humidity/pressure. The results are sent on an MQTT queue.

https://github.com/sweharris/esp8266-bme280

3 NodeMCUs for $15 at https://www.amazon.com/gp/product/B07LCMNXTN/

3 BME820s for $13 at https://www.amazon.com/KeeYees-Temperature-Humidity-Atmospheric-Barometric/dp/B07KYJNFMD/

That is one style yes but the other style looks like this that little end bit can be inside some chunk of metal to have some thermal mass so the temp readings don't swing wildly.