| 摘要 |
1480452 Ultrasonic transmit/receive system FIAT SpA 27 May 1975 [1 Aug 1974] 23143/75 Heading G1G A control circuit for two or more Piezo-electric transducers 7, 7<SP>1</SP> cyclically operable to transmit and receive ultrasonic signals comprises a transistor 1 turned on and off by a timing circuit 2 to induce transmission pulse signals by ringing inductor 3, a Zener diode 5 which blocks the circuit's D.C. supply voltage but conducts when subjected to the high voltage induced pulses, a decoupling diode 6, 6<SP>1</SP>, to prevent interaction between transducers, and a series combination of a resistor 8, 8<SP>1</SP> and a diode 12, 12<SP>1</SP> across each transducer whereby the diode 12, 12<SP>1</SP> conducts during the transmission pulse but is not biased into conduction by received signals from the transducer. In the embodiment shown, negative-going voltages at the transducers are suppressed by diodes 15, 151 and receiver amplifiers 9, 9<SP>1</SP> are protected from negative overload voltages by diodes 13, 13<SP>1</SP>.
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