Motion sensor

A small, compact motion sensing device suitable for use as a portable alarm system comprises a piezo-electric bar which is mounted with a small weight so as to provide an output voltage when disturbed in any way. The output is amplified using a field effect transistor with an unusually large source resistor thus requiring a very small operating current. When triggered a piezo-electric buzzer driven by a transistor, coil and diode arrangement ensures high electrical energy to sound energy conversion. The sensitivity is adjustable over a very wide range using a potentiometer which does not affect the low power consumption. Time delays and an automatic reset can be incorporated for greater convenience of operation. The system can also be used to control other external alarms and devices.