Wandee Petchmaneelumka

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A method for realizing a floating resistor based on operational transconductance amplifiers (OTAs) is presented in this paper. The proposed design is composed of only OTAs without any external resistor. The magnitude of the obtained resistance is electronically varied by adjusting the external bias currents of OTAs. Both a positive and a negative resistance(More)
This paper presents the Pulse Induction Metal Detector Using Sample and Hold Method. The proposed method is to measure output voltage from search coil. The system consists of the pulse generator circuit, amplifier circuit, integrator circuit, three mono-stable circuits, sample and hold circuit, comparator circuit and display circuit. The voltage output(More)
In this paper, a triangular-to-sawtooth waveform converter and a control logic circuit have been described. Using two designed circuits connected with OTA-based sine-to-triangular wave converter and demodulator, a resolver-to-DC converter is proposed. The converter linearly produces output signal proportional to the shaft angle in full range of 360deg.(More)
A simple technique to produce a linear signal from a displacement transducer, linear variable differential transformer (LVDT), is introduced in this paper. The two-quadrant divider is used to precede the ratio of a different and sum of the two winding signals from the LVDT instead of a four-quadrant divider of a recent approach. The two- quadrant divider is(More)
This article presents a current signal sample-and-hold (S/H) circuit using 0.5 mum CMOS technology. A current minimum circuit is used to sample the input signal in place of a sampling switch used in the conventional S/H circuit. The current peak detector is used to hold the signal from the minimum circuit in the "hold" state. The proposed configuration is(More)
A simple technique for implementation of resolver-to-DC converter is presented in this paper. The obtained output in form of DC voltage is linearly proportional to the position of motor shaft angle. The configuration of proposed converter consists of commercial available circuit building blocks such as demodulator, sine-to-triangular wave converter, logic(More)
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(More)
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(More)
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(More)
This paper presents a simple circuit technique based on commercially available devices for measuring the amplitude of transient signals. The proposed technique produces digital output proportion to the amplitude of sinusoidal analog input signal without low-pass filter. The realization method employs a peak detector, a comparator, an analog-to-digital(More)