The principle of self-excitation and other excitation of ultrasonic sensor drive circuit

- Sep 01, 2020-

   The driving mode of the ultrasonic sensor used for transmission is divided into self-excitation and other excitation.


   Self-excited drive circuit The self-excited drive circuit, like a quartz oscillator, uses the resonance characteristics of the OSENON ultrasonic sensor to make it oscillate around the resonance frequency.
  

   The following figure shows a self-excited transistor oscillation circuit, where the frequency of the ultrasonic sensor is 40kHz. Figure 9-14 (a) shows the Colpitts oscillator circuit. Ultrasonic sensors oscillate at an inductive frequency. The oscillation frequency is inconsistent with the series resonant frequency. The reason for this phenomenon is the influence of the anti-resonant frequency on it, specifically C. , C: The adjustment will affect. Figure 9-14 (b) shows a self-excited transistor oscillation circuit with an oscillation control terminal. Since it connects the ground in Figure 9-14 (a) to the emitter of transistor VT2, the oscillation will stop when VT2 is turned off.


        ultrasonic sensor drive circuit design  

(a) Colpitts oscillation circuit (b) Self-excited transistor oscillation circuit with control terminal
Figure 9-14 Self-excited transistor oscillation circuit
  
The self-excited operational amplifier oscillates amplifying circuit, the oscillation frequency of this circuit is close to the series resonance frequency, so the efficiency will be much higher than the self-excited transistor oscillation circuit. The operational amplifier used in this circuit is MC34082 integrated circuit. In fact, as long as the conversion speed is above 10 l.t, V/l_t, s operational amplifiers can be used.

There are many ways to design the ultrasonic drive circuit, which must be designed according to the needs of users. If you have more information, please contact OSENON engineers, you can always get the solution you want.all model type of ultrasonic sensors

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