The cooker hood is a wonderful invention for removing excess fumes and steam from the kitchen. But like all electrically-powered devices, it only works when it is turned on. This was the problem facing [Peter], whose family are enthusiastic cooks who frequently forget to hit that switch. His solution? An automatic cooker hood switch that comes on when the cooker is in use, and stays on long enough afterwards to fully dissipate the fumes.
At its heart is a current transformer on the 3-phase stove power line, and we’re treated to a lesson in reading from these devices with an Arduino. They have a shunt resistor across which to produce a voltage, and their AC output is placed upon a reference DC voltage to supply the microcontroller pin. The impedance is quite high, so when the sensor had to be placed a distance from the microcontroller it necessitated an op-amp buffer. The readings then cause the Arduino to trigger a pair of relays to switch on or off the cooker hood. We can imagine that the family kitchen is thus a much pleasanter environment for it.
Cookers can also provide quite a hazard when they are left on. To that end, we’ve also featured a cooker alarm in the past.