Hi, I'm new to this forum!
Me and my co-worker are working on a physics laboratory (we're physics students) and we are trying to control the temperature of 4 compost samples that are decomposing (4 identical experiments). For this we bought:
- An Arduino Uno.
- 4 Pt100 sensors.
- 4 cylindrical resistors to heat up the compost. The compost is on a cylindrical glass jar and the resistor wraps the entire jar so that the heat comes from the outside to the inside of the jar through the glass walls of the jar.
- 4 relays.
Our plan was to use the Arduino as a PID controller to keep the temperature of the compost samples at (52±2)°C by turning on and off the heaters using the relays. Sadly, we thought that the Pt100 sensor came with the module necessary to use it with the Arduino and it didn't, and now we realize that the modules like the MAX31865 are beyond are budget for this experiment.
So that is the problem we are facing. To overcome this problem we would need to either:
- Find cheaper modules that could work for this setup.
- Build the modules ourselves (which we leave as a last resort because we haven't done something like that before)
- Find a more affordable setup and leave the Pt100 sensors unused (which is sad because it's wasted money). We found that the LM35 sensor is a cheap sensor that works in our temperature range, is decently accurate and is way cheaper than buying the modules for the Pt100 sensors.
Any help, advise or personal experience that could help us with this project is deeply appreciated!
- The cylindrical resistors that we use for heating are ~140Ω and to heat them up to (52±2)°C we would work on a voltage range of 40V to 70V.
- The compost will be moist so we may need to wrap the thermometer on some kind of material that is heat conductive to protect it (if it's necessary).
- We plan on running this experiment for months so supervision will be minimal. That is why we will use a PID controller.