Arduino Uno Rev R3
The Arduino Uno is a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.
There are several types of Arduino boards, however we will only be using the UNO. Most all the Adruino versions will work for these projects, but it may be easier for beginners to follow the Arduino Uno R3.
Visit Ghost Box Hacks for more projects and info on making your own Paranormal Equipment with the Arduino Uno.