I designed this unit for my 2001 model Suzuki GSX-R1000 and was designed to be minimally intrusive to the bike's electrical system; only a battery connection is needed. The system monitors battery voltage and two mercury switches (X and Y planes). It doesn't immobilise engine. The unit uses a 12V/20mA/105dB piezo speaker with a inbuilt oscillator. The sound from it is very loud.
The unit draws about 10mA idle. When alarm goes off, uses about 30mA. This will be improved in future iterations. Also, case design will be improved. That external capacitor you see is because I didn't have room to fit it inside the box.
This design served me well for a year until I brought a new motorcycle and designed a better alarm system.