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Author: search.filters.author.Rerkratn, ApinaiSubject: search.filters.subject.Sample and hold

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    Simple LVDT demodulator
    (2020-10-13)
    Rerkratn, Apinai
    ;
    Luangpol, Amata
    ;
    Riewruja, Vanchai
    ;
    Petchmaneelumka, Wandee
    A simple technique to realize demodulator for linear variable differential transformer (LVDT) is presented in this paper. The proposed LVDT demodulator is based on sample and hold technique. The proposed scheme consists of peak detector, phase detector, monostable circuit, sample and hold circuit, and controllable unity-gain inverting/noninverting amplifier. The presented technique employs the simple and low-cost devices such as op-amp, and digital logic gate. Experimentation with the commercial LVDT model OP12.5G from Solartron metrology shows that the proposed LVDT demodulator provides the output voltage corresponding to the movement of LVDT core with satisfactory values and good linearity. The maximum error of the proposed demodulator is about 1.5%. In addition, the output magnitude of proposed LVDT demodulator can be adjusted by variable resistor (VR1) without the external circuit requirement.
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    Simple LVDT signal conditioner
    (2017-06-07)
    Petchmaneelumka, Wandee
    ;
    Songsuwankit, Kanoknuch
    ;
    Rerkratn, Apinai
    ;
    Riewruja, Vanchai
    A method to implement a signal conditioning circuit for a linear variable differential transformer (LVDT) is proposed in this article. The proposed signal conditioner can be used instead of a synchronous demodulator in the tradition approaches. The output signal of the signal conditioner is linearly proportional to the moving core of the LVDT with fast response. The realization technique is based on the use of an analog integrator to determine the LVDT signal at the half period of the excitation signal. The proposed signal conditioner provides without low-pass filter in the signal path. Therefore, the response time of the proposed technique is settled within half period of the excitation signal. The devices used in the proposed signal conditioner consist of basic commercially available devices such as operational amplifier (opamp), comparator, analog switch and one-shot timer. Experimental results demonstrated the performance of the proposed conditioner are included. The proposed technique is attractive in terms of simple configuration and low cost.
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    Ultrasonic measuring circuit using sample and hold method
    (2008-12-01)
    Rerkratn, Apinai
    ;
    Akejakrawan, Sakolkrit
    ;
    Kaewpoonsuk, Anucha
    This paper presents the simple ultrasonic measuring circuit using sample and hold method. The proposed method is to measure the transit time of ultrasonic wave in fluid. The system consists of the pulse generator circuit, amplifier circuits, band pass filter, detector circuit, comparator circuit, timing circuit, saw-tooth generator circuit, and sample and hold circuit. The voltage output signal of the proposed technique is proportional to the transit time. The sugar solution with differential concentrations was measured in our experiment as an illustrative case study. Experimental results show that the proposed method can measure the transition time of the ultrasonic signal with satisfied sensitivity and good linearity. © 2008 SICE.