As we mentioned in Chapter 1, Arduino and iOS – Platforms and Integration, we need a Wi-Fi shield (http://www.arduino.cc/en/Main/ArduinoWiFiShield) and a micro SD card formatted with FAT16 (take a look here for more details: http://www.arduino.cc/en/Reference/SDCardNotes). The SD card is used to permanently store the activation times when Arduino is powered off, so its size is not so important.
In this project we need some additional components:
Optoisolator MOC3041
330 Ω resistor, 0.5 W
330 Ω resistor, 0.25 W
Red LED
TRIAC BTA08-600
The TRIAC is capable of 8 Amperes RMS at 600 V, which is about 1700 watts at 220 V. You can use another TRIAC model of the same family (for example, BTA16) if you have a more powerful external appliance.