When measuring temperature, you’re often concerned with an overall value. Baking a cake means setting the oven to a certain temperature, thermostats generally set a single house temperature, and even solder profiles assume a single consistent temperature. In reality, the temperature within an oven or other zone will vary, and one might especially wonder about the behavior of an infrared PCB heater, such as the T-962 reflow oven that seller VoltLog uses.
After finding that his oven did produce inconsistent heating, he decided to look into this further. To obtain the proper data, VoltLog created the Voltlogger temperature logging device, capable of recording data from 10 thermocouples simultaneously.
The board uses ESP32 for control, along with a Micro SD card reader for logging. Card functionality has been tested at up to 64 GB, and is set up to record temperature values once every second, allowing for a significant amount of logging. Timestamps are generated via NTP, thanks to the ESP32’s WiFi interface. This functionality would also allow for wireless control and logging, thought this appears to be a potential future innovation.
To use it, you’ll just need to provide a FAT-formatted Micro SD card, and as many K-type thermocouples as you wish to use. More explanation on the build is seen in the video below, and code/design files are on GitHub. As for the oven itself, VoltLog plans to discuss its performance performance after he gathers enough data:
