A powerful but simple ultrosonic cat deterrent. This device emits a siren-like tone that sweeps between 23kHz and 25kHz for 30 seconds every 4 minutes. In between alerts the Arduino goes into sleep mode and also puts the connected class D PA into sleep mode. The squarewave output is available at pin 7 and pin 6 provides the drive for a flashing LED Strobe and pin 5 provides a shut-down signal (pin LOW) for an attached class-D amplifier.