The system was working well but, as I’m ever the tinkerer, I couldn’t leave well enough alone. The off-the-shelf Inkbird Humidity Controller IHC200 just didn’t have the functionality that I really wanted so instead I decided to design and build my own humidity controller. My controller is based around a PIC18F microcontroller and a SHT-30 Mesh-protected Weather-proof Temperature/Humidity Sensor that has an excellent ±2% relative humidity with a range from 0 to 100% (it is difficult to find a sensor capable of 100% humidity). There are three different switchable AC circuits (only two are implemented at this time).
Operation:
1. When the humidity reaches 18% and the outputs for two solenoids, a high volume air pump, and the heater are turned on
2. When the humidity drops back to 22% the heater is turned off and the two solenoids and a high volume air pump continue to run for 45 minutes to purge any remaining moisture (once the desiccant tube cools the humidity will drop from 22% to 2.5%)
3. All AC outputs are turned off and monitoring continues
* The LED on the PIC18F board flashes one time (for 1/3rd second) for each 10% of humidity followed by one time (for 1/5th second) for each 1% of humidity, so that it is easy to know the current humidity level (5 long flashes with 7 short flashes means the humidity is between 57%).
Note: Probably not necessary but I added a small headsink to the Triac that powers the solenoids. The Triac would get hot (could be touched), rather than risk pre-mature failure I added the heatsink.
Interested in how I got to Version 3.0? You can checkout the previous versions
Version 2.0: Link
Version 1.0: Link
No Comments