Riewruja, Vanchai
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Riewruja, Vanchai
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Riewruja, V.
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vanchai.ri@kmitl.ac.th
103 results
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Item type:Publication, A simple CMOS-based algorithmic ADC(2007-12-01); ; This paper presents a one-bit cell of reverse Gray-code algorithmic analog-to-digital converter. The proposed converter comprises of full-wave rectifier, current mirrors, and current comparator. The realization method is simple, small in size, and suitable for integrated circuit form. The design strategy is based on the MOS biased at the edge of conduction to provide a low accumulated error and a low distortion in the transfer characteristic. An N-bit resolution can be achieved by cascading of the N proposed one-bit cells. PSPICE simulation results supporting the characteristics of proposed circuit are agreed with the expected values. © ICROS. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A simple amplitude detector-based demodulator for resolver converters(2010-12-01); This paper presents a simple method based on sinusoidal-amplitude detector for realizing the resolver-signal demodulator. The proposed demodulator consists of two full-wave rectifiers, two ±unity-gain amplifiers, and two sinusoidal-amplitude detectors with control switches. Two output voltages are proportional to sine and cosine envelopes of resolver-shaft angle without low-pass filter. Experimental results demonstrating characteristic of the proposed circuit are included. ©ICROS. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Electronically adjustable phase shifter using OTAs(2010-12-01); ; First-order phase shifter using operational transconductance amplifiers (OTAs) as active elements is presented in this paper. The corner frequency of the proposed phase shifter can be adjusted by electronic means. The purpose of this paper is emphasized on simple configuration and low cost. The phase response between input and output signals against the operating frequency is varied from 180 to 0 degrees of phase lead. The principle of the proposed circuit is confirmed by simulation and experimental results. To verify the proposed circuit performance, the sinusoidal oscillator is provided for circuit application. ©ICROS. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Linear Variable Differential Transformer Signal Conditioning Circuit Based on Phase-Locked LoopThe purpose of this paper is to propose a novel technique for extracting the position signal from an inductive displacement transducer named a linear variable differential transformer (LVDT). In general, the movement of the LVDT core causes its primary inductance change in linear form. The primary winding of the LVDT is used as a time-dependent element for the triangular and square wave generator, which can be called self-oscillation, to generate frequency. The advantage of the proposed technique is that it can measure the displacement using the LVDT without an external oscillator. The change in primary inductance causes the frequency deviation generated by the oscillator. The deviated frequency is captured and converted into a voltage signal using the principle of the phase-locked loop. All the components used in this study are commercially available. The merits of this proposed technique are simple configuration, small size, and low cost. Moreover, the operating range of the LVDT can be extended without the limitation of the nonlinear transfer characteristic. The performance of the proposed technique is discussed in detail and confirmed by experimental implementation. Experimental results show that the maximum error from the proposed technique is about 0.42% and the operating range of the LVDT can be extended to more than 200%. It can be seen that the proposed technique is suitable for embedded measurement in small or micro robots. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simple square-rooting circuit using OTAs(2008-08-28)A method to implement a square-rooting circuit is described. The proposed circuit employs operational transconductance amplifiers (OTAs) as the only active elements. The implementation technique is based on an electronically variable resistor formed by the OTA, where the magnitude of the resistance is controlled by the output current, to provide the square-rooting function. The proposed scheme can operate with both a voltage input and a current input signal. The purpose of the circuit is emphasised in terms of simple configuration, high accuracy and low cost. Experimental results showing the circuit performance are presented. © 2008 The Institution of Engineering and Technology. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Temperature Compensation for Transformer-type TransducerA novel technique to compensate the temperature effect of a transformer-type transducer is proposed in this paper. The effect of the ambient temperature on the transformer-type transducer is investigated from a primary-winding current. The advantage of the proposed technique is that the temperature effect is compensated without requiring a temperature sensor, making it suitable for applications in robotic and automation systems operated in harsh environments. The primary-winding current of the transducer is generated using a second-generation current conveyor (CCII). The excitation signal of the transformer-type transducer is driven by the CCII and the current flowing through the primary winding is transferred to an output signal of the CCII. The deviation of the primary-winding current due to the temperature effect is evaluated from the output signal of the CCII. The temperature effect on the transducer is manipulated by a closed-loop principle using a subtract-and-sum action instead of a traditional proportional-plusintegral action to eliminate the deviation of the primary-winding current. Therefore, the temperature effect on the transducer is compensated. A linear variable differential transformer (LVDT) is used to demonstrate the proposed technique, whose performance is discussed in detail and confirmed experimentally. All devices used in this experiment are commercially available. Experimental results show that the measured error of the output signal from the LVDT at 70 C can be reduced from 6.2% without temperature compensation to 0.06% by using the proposed technique, which has the advantages of a low cost, simple configuration, and high performance. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Wireless Carbon Monoxide Level Control and Monitoring SystemThis paper proposes an online carbon monoxide control and monitoring system. The proposed system comprises an MQ-7 CO gas sensor module, a DHT11 digital temperature and humidity sensor module, an ESP8266 module, and a Relay Module. The ThingSpeak platform is used to create HMI for online monitoring of CO level, temperature, humidity, and status of the ventilation fan. This proposed system can measure CO and monitor all parameters of measurement data, alert users when CO values exceed the set value. In addition, the measured CO values are used to control the ventilation system operation (ON or OFF) to maintain the CO at a non-harmful level. The experiment testing and results with three conditions show that the proposed system can measure and monitor CO level, temperature, and humidity online with satisfying values. The ventilation fan can operate with function as a design procedure and maintain CO at a non-harmful level. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, CMOS-based integrable electronically tunable floating general impedance inverter(1997-01-01); Surawatpunya, CharrayAn integrable electronically tunable general impedance inverter (EGII), implemented by a MOS circuit design technique, is described. The driving point impedance of the EGII, that is inversely proportional to a given impedance, can be a positive or a negative value and can be electronically varied. The realization scheme employs proposed voltage-to-current transducers (VCTs) that are designed based on a linearizing technique, as basic circuit building blocks. The applications of the EGII as a gyrator, a general impedance converter and a floating capacitance multiplier are discussed. Experimental and simulation results that demonstrate the characteristics of the EGII are included. © 1997 Taylor and Francis Group, LLC. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Enhanced sinusoidal amplitude detector for fast response applications(2013-03-28); In this paper, an enhanced sinusoidal-amplitude detector suitable for fast response applications is proposed. Implementation method based on commercially available devices employs a novel control signal generator to improve operation speed of previously reported sinusoidal amplitude detector. The control signal generator used consists of a time-delay circuit, AND logic gate, and three comparators. The enhanced amplitude detector provides faster amplitude detection as well as smaller operation error for amplitude input changes. Experimental results verify a good agreement with theoretical expectation. © 2013 ICIC International. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Integrable CMOS-base realization of current conveyors(1991-01-01); Cheevasuvit, FusakSimple integrable circuits for implementing both positive and negative second generation current conveyors (CCII) are described. The realization method is suitable for fabrication using CMOS technology. Simulation and experimental results demonstrating the characteristics of the method are also included. © 1991 Taylor & Francis, Ltd.