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Author: search.filters.author.Petchmaneelumka, WandeeSubject: search.filters.subject.Capacitive sensor

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    Capacitive sensor readout circuit based on sample and hold method
    (2022-04-01)
    Petchmaneelumka, Wandee
    ;
    Phankamnerd, Phirapong
    ;
    Rerkratn, Apinai
    ;
    Riewruja, Vanchai
    This paper presents a capacitive sensor readout circuit using sample and hold method. The proposed readout circuit is used to convert capacitance from sensor to DC (direct current) voltage output. The basic structure of readout circuit consists of the pulse generator circuit, differentiator circuit, amplifier circuit, monostable I circuit, monostable II circuit, and sample and hold circuit. The proposed technique is based on the change of time constant from differentiator circuit corresponding to the measurement capacitance. The sample and hold circuit is used for sampling output voltage from differentiator circuit. The output voltage of the proposed readout circuit is proportional to measurement capacitance. The standard capacitors with different capacitance are used to test the proposed converter performance. Experimental results show that the proposed readout circuit can convert measurement capacitance to output voltage with satisfied values, good linearity and high sensitivity.
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    A versatile interface circuit for capacitive and resistive sensors
    (2017-12-13)
    Petchmaneelumka, Wandee
    ;
    Mano, Pitsini
    ;
    Wutikun, Tanatat
    ;
    Riewruja, Vanchai
    This paper presents a circuit design technique for realization of a versatile interface circuit for capacitive and resistive sensors. The proposed method is based on the use of operation of relaxation oscillator. Time periods generated from two relaxation oscillators are employed for the reference signal and another sensing signal from sensor. The output signal obtained in the form of time period is proportional to the sensing value from sensor. The proposed approach provides the attraction in terms of simple configuration and low cost. The proposed circuit performances confirmed by the experimental results using commercial devices are agreed with the expected values.
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    Simple capacitance-to-time converter
    (2017-02-18)
    Petchmaneelumka, Wandee
    ;
    Wutikun, Tanatat
    ;
    Rerkratn, Apinai
    ;
    Riewruja, Vanchai
    A method for implementing of a capacitive sensor interfacing circuit is proposed in this paper. The time period generated from a simple relaxation oscillator is utilized to determine the time period obtained from the capacitive sensor. The output parameter of the proposed converter is in the form of the time period. The capacitance of the sensor can then be calculated using ratio metric operation. The proposed converter can linearly convert the capacitance from the sensor to the time period. The purpose of the proposed converter plays an attention in terms of simple configuration and low cost. Performance of the proposed scheme is demonstrated by experimentally implementation. The resulting confirmed that the performance of the proposed converter is in good agreement with the expected value.
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    OTA-based capacitance-to-period converter for capacitive sensors
    (2013-03-28)
    Kanjanapart, Naratorn
    ;
    Cheypoca, Thepjit
    ;
    Riewruja, Vanchai
    ;
    Petchmaneelumka, Wandee
    A simple design technique for realization of a capacitance-to-period converter based on operational transconductance amplifiers (OTAs) is presented in this paper. The proposed principle utilizes the behavior of astable multivibrator. The configuration of converter is implemented using commercial available and low cost devices. The obtained time period is proportional to sensing capacitance. The conversion gain of proposed scheme can be changed by electronic means. Circuit performances verified by experimental results are agreed with the expected values. © 2013 ICIC International.
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    Simple interface circuit for resistive/capacitive sensors
    (2013-01-01)
    Tongcharoen, Jakkapun
    ;
    Petchmaneelumka, Wandee
    ;
    Cheypoca, Thepjit
    ;
    Rerkratn, Apinai
    ;
    Riewruja, Vanchai
    This paper presents a method to realize interface circuit for resistive and capacitive sensors. The proposed circuit employs commercially available devices to generate the output signal in form of time period, which is linearly proportional to the both of sensing resistance and capacitance. Circuit configuration is simple and small in size. Experimental results verifying the performances of the proposed circuit are also included.