Quantity   Component name
1 × IntrudAlert Door/Window Alarm I had four of these in the junk box, I assume similar units can still be purchased. The enclosure is reused along with the power switch, speaker and transformer that drives the speaker.
1 × TI MSP430G2553 20 pin PDIP used in the prototype. 20 or 28 pin TSSOP package will be used in final design.
1 × Pololu S7V8A Adjustable Step Up / Step Down Voltage Regulator
1 × Allegro A3214 Low power Hall-Effect Switch
1 × 2N3904 NPN BJT
1 × 32 kHz Crystal
1 × 1k and 47k Resistors