This is a simple Arduino project that was written to automatically turn off a commercial iron (with no auto-off functionality) after a certain amount of time.
It shows the amount of time remaining on a seven-segment display. The decimal points on the display are alternated each time the main loop runs to serve as a heartbeat to indicate the program is still running properly.
There is a timer-based ISR that is used to drive the display. The reset button triggers another ISR that resets the time left back to the maximum value.
Components used:
- Metro Mini (Adafruit Link) (this should work with all Arduinos including the Uno - The Arduino Mega and some others may need minor tweaks to the timer-based ISR)
- IoT Power Relay (Adafruit Link)
While it is possible to build the AC components yourself, I highly recommend buying a pre-made device such as the the IoT Power Relay.
Improvements to be made:
- Make reset switch less sensitive - sometimes power fluctuations cause it to trigger. I have somewhat fixed this by using a better power supply and adding a capacitor in parallel, but I think thewre is likely a simpler more fool-proof way.