Ultrasonic transmitter circuit diagram

Ultrasonic transmitter circuit diagram is shown below. Ultrasonic transducer applied voltage size is an important factor in the decision of the detection distance. Applied voltage to affect the internal electric field strength of the piezoelectric ceramic transducer in the material, thereby affecting the deformation of the diaphragm and the piezoelectric conversion efficiency. The most commonly used method is to use 7404 series inverter as ultrasonic transmitting transducer voltage driver chips, although this simple design, the price is low, but driving it produces a lower peak voltage, the maximum also only about 7v, greatly reducing the detection range. To address this situation, the paper decided to use MAX232 instead of inverters to a push-pull approach to increase the ultrasonic transmitter transmitting transducer drive voltage and improve the piezoelectric conversion efficiency.Experimentally measured, MAX232 can be about 5v TTL level converter into 232 level 9.2v or so, peak to peak up to 18.5v, the detection range of up to 5m, is also approximately 50% duty cycle, to overcome the detection range of nearly shortcomings, and other performance indicators fully meet the design requirements. The program sends ultrasound to 10 cycles of a sequence, separated by 32768us between two sequences, namely T1 timer overflow time.When T1 overflows, the system displays an error and re-emit ultrasonic waves into the next measurement. System transmitter circuit shown in Figure 2.

　　

　　Figure system transmitter circuit diagram