I was making simple ventilation control for my farm.
PHOTOS and SCHEMATIC are here: http://ge.tt/3pQxzFl
Main functions of system: * Display current temperature & relative humidity * Intelligently control 4 fans depending on average temperature of current period * Ability to set target temperature via buttons
- Relays just open/close 3-phase contactors for each fan. There are buttons for manual contactor ON/OFF + button to break the Arduino relay circuit from contactor box.
- Arduino UNO Rev3
- DHT21 sensor
- 4 optoisolated relay array
- LCD keypad shield 16x2
Features: * Current temperature is being smoothened using moving average * Fans are being turned on/off every 60 secs * On sensor failure - fans are turned off & arduino freezes throwing out an error * There is a 2 sec delay between starting each fan (so to not overload line - each fan ~0.55kW) * Target temperature is being saved to EEPROM
Arduino source code: https://gist.github.com/blacktea/5945177
P.S. This is my first project with Arduino and with low-voltage electronics. I will be very glad to receive comments and criticism.