Presto Dehydrator Control Kit

thingiverse

It appears you're sharing a detailed project log for modifying a dehydrator to add temperature control and automation using an Arduino board. The modifications involve adding relays, a sensor, a 5V power supply, and a user interface with buttons. The goal is to create a more efficient and easy-to-use dehydration process. Here are the main points from your project log: 1. **Adding Temperature Control:** - Installed a temperature sensor (DS18B20) in the dehydrator's heating element compartment. - Routed the sensor wire through a grommet on the base for protection. 2. **Power Supply:** - Used an old 5V Bluetooth headset charger as the power supply for the Arduino. - Soldered THHN 14awg wiring to the wallwart's outlet prongs and fed it through the relay box hole to connect it to line voltage. - The 5V line passes through the relay box and into the controller box, where it's soldered to a 5V bus board. 3. **Wiring:** - Determined what stock wiring needed to be connected where based on notes made during the project. - Used wire nuts to secure THHN near the plug cord strain relief and electrical tape with zipties for additional security. 4. **Updates and Fixes:** - Version 2 of the Arduino code shortened the button delay from 4 seconds to 1 second, kept the fan on during drying mode, and added a bigger 5V line ripple capacitor. - Version 3 removed the button delay and added an off mode. It follows a cycle of OFF - Filament Select - Dry - Holding - OFF... - Added 4k7 pullup resistors due to phantom button presses caused by induced spikes when the motor turns off in holding mode. - Updated STL files for the relay box and lid with correct printing orientations and no rectangular window that could be used to pry into the relays. 5. **Other Changes:** - Redesigned the control part with a 2-piece button mount design, which prints more easily and allows for smooth button operation without requiring hardware. - Added an RC snubber in parallel to the motor lines (0.1uF+120ohm) to absorb transients caused by the fan relay turning off and cure phantom button press events reliably. This project showcases a detailed approach to modifying existing appliances with automation technology, ensuring efficient and safe operation.