The Mechanical Following Puppy

Ultrasonic Transmitter

In order to call the puppy, an ultrasonic transmitter operating at 40KHz must be activated by the owner. The transmitter is a crystal-locked CMOS gate oscillator employing a hex inverter as its driving element. The 40KHz square-wave output of the oscillator is fed to the transmitting transducer 180 degress out-of-phase to get the maximum output. When pointed in the general direction of the puppy, the receivers on the puppy process the ultrasonic signals and send the information to the microprocessor controller.