Abstract:   A novel 8channel array emitting and singlechannel receiving circuit is designed to solve the problems of low acoustic emission energy, low tiny flaw detection rate and complex circuit structure for pipeline flaw ultrasonic array detection. A singlechipmicrocomputer is applied to generate 8channel control signals for emission circuit stimulating adjustable time sequence and repetition frequency. Then, the transducers are stimulated by the 8channel highvoltage narrow pulses. A multiplexer is used in receiving circuit for echo signal time sharing multiplex. The designed array circuit is applied to pipeline sample ultrasonic testing. Artificial flatbottom hole with 2mm diameter and 3.6mm height and crack with 10mm length, 0.5mm width and 1.5mm height are inspected by using the designed circuit. In the experiments, wall thickness is also measured with an average relative error of 0.51%. Testing results show that the circuit is stable and reliable.

Key words:  pipeline testing, ultrasonic, tiny defect, array circuit