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OP-AMP based interface circuit for resistive sensor with lead-wire-resistance compensation
(2019-04-01)
Kaewpoonsuk, Anucha
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Katman, Ratchanoo
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Rerkratn, Apinai
This paper presents a simple technique to implement the resistive sensor interface for remote measuring. The circuit is designed using a relaxation oscillator to generate a square wave signal. The time difference during charging and discharging a capacitor is directly proportional to the sensor’s resistance. The structure of the circuit is composed of two op-amps, three bipolar junction transistors, a capacitor, four fixed resistors and a variable resistor. Features of the proposed circuit are single-supply operation and direct interface with a microcontroller without an analog-to-digital converter. In addition, the lead-wire resistance is automatically compensated. When the resistance values of the sensor are varied in the range of 500-1500 O with lead-wire resistance values of 0-100 ω, the result of the circuit testing is found that the maximum error is approximately equal to 1.15% of full scale. The performance of the circuit is in accordance with principles proposed.
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Simple and low-cost readout circuit for differential resistive sensors
(2018-09-01)
Katman, Ratchanoo
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Rerkratn, Apinai
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Kaewpoonsuk, Anucha
In this paper, a simple and low-cost readout circuit for differential resistive sensors is presented. The realization method is based on the relaxation oscillation technique, which utilizes the operational amplifiers (op-amps) with a single supply voltage. The oscillating output Duty-Cycle is proportional to the difference of two sensing resistances. In comparison with the traditional voltage divider circuit or the Wheatstone bridge circuit or the previously reported readout circuit based on CCIIs, the proposed circuit can be interfaced with microcontroller without using an analog-to-digital converter. Theoretical predictions are supported by the PSPICE simulation results and the experimental data. In applying a slide potentiometer with changes of slider positions of ±15 mm, it is found that the maximum error of the proposed circuit is approximately-2.90% of full-scale. Copyright © 2018 Praise Worthy Prize S.r.l.-All rights reserved.
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A versatile interface circuit for capacitive and resistive sensors
(2017-12-13)
Petchmaneelumka, Wandee
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Mano, Pitsini
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Wutikun, Tanatat
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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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Interface circuit using operational conveyors for differential resistive sensors
(2013-09-02)
Julsereewong, Amphawan
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Julsereewong, Prasit
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Rungkhum, Tipparat
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Sasaki, Hirofumi
In this paper, a simple and accurate circuit for interfacing differential resistive sensors is presented. The realization method employs three operational conveyors as active elements to provide voltage output linearly proportional to sensing resistance change. The performance is confirmed through PSPICE simulation and experimental results. © 2013 IEEE.
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OTA-based capacitance-to-period converter for capacitive sensors
(2013-03-28)
Kanjanapart, Naratorn
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Cheypoca, Thepjit
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Riewruja, Vanchai
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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 resistance-to-frequency converter with lead-wire-resistance compensation
(2013-03-28)
Julsereewong, Amphawan
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Petchmaneelumka, Wandee
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Rungkhum, Tipparat
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Yahara, Mitsutoshi
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Fujimoto, Kuniaki
This article presents a simple technique to realize a resistance-to-frequency converter for single resistive sensor-based remote measurements. The proposed realization method uses commercially available devices to generate output frequency, which is linearly proportional to sensing resistance deviation. Experimental results are shown that not only the good circuit operation but also the effective lead-wire-resistance compensation of the proposed technique can be obtained. © 2013 ICIC International.
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Simple interface circuit for resistive/capacitive sensors
(2013-01-01)
Tongcharoen, Jakkapun
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Petchmaneelumka, Wandee
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Cheypoca, Thepjit
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Rerkratn, Apinai
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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.
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Simple interface circuit with lead-wire-resistance compensation for single resistive sensors
(2012-12-01)
Petchmaneelumka, Wandee
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Julsereewong, Prasit
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Julsereewong, Amphawan
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Tongpakpanang, Jaturon
A simple interface circuit for single resistive sensor-based remote measurements is presented. The realization method using commercially available devices provides not only the output signal linearly related to resistive sensor changes but also the compensation of effect due to lead-wire resistances. Performance of the proposed circuit is confirmed through experimental results. © 2012 ICROS.
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Simple resistance-to-period converter for resistive sensors
(2012-12-01)
Tongpakpanang, Jaturon
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Rerkratn, Apinai
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Kaewpoonsuk, Anucha
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Riewruja, Vanchai
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Petchmaneelumka, Wandee
A method for realization of resistance-to-period converter is introduced in this article. The principle of converter utilizes the behavior of designed astable multivibrator, which is implemented using commercial available and low cost devices. The operation of proposed converter circuit is in current mode. Therefore, the resistance is linearly converted to period and also converted to frequency with invert proportional relationship. The conversion gain of the proposed converter can be adjusted by electronic means. The configuration of the proposed converter is simple and small in size. Experimental results verifying the proposed converter performance are included in detail. The relative error of about 0.8 % is observed. © 2012 ICROS.
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Resistive sensor interface circuits using operational conveyor and operational amplifier
(2012-03-01)
Julsereewong, Amphawan
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Julsereewong, Prasit
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Rungkhum, Tipparat
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Sasaki, Hirofumi
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Isoguchi, Hiroshi
A simple technique based on commercially available devices to implement three interface circuits for both differential resistive sensors and single resistive sensors is presented in this article. Each proposed scheme uses an operational conveyor and an operational amplifier as active elements. Surpassing the previously reported circuits, the proposed circuits provide not only simpler structures but also higher accuracy. Performances of the proposed circuits are verified through computer simulations. © 2012 ICIC International.

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