KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Access type: UnknownSubject: search.filters.subject.operational amplifier

Search Results

Now showing 1 - 3 of 3
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Pwm and Differential Pwm Generation Circuits Based on Conventional Schmitt Trigger Cooperating with Integrator: Analysis and Implementation
    (2025-01-01)
    Saechia, Sukkharak
    ;
    Kaew-In, Chanapat
    ;
    Chatchaiphat, Nisukan
    ;
    Wardkein, Paramote
    This paper presents systematic approaches to generate the Pulse Width Modulation (PWM) signal by leveraging a simple configuration based on an operational amplifier (op-amp) comprising the Schmitt Trigger circuit and the integrator circuit. Two PWM modulation techniques are proposed according to the input position of the information signal. First, utilizing inverting terminal of the Schmitt Trigger circuit as an input terminal can function as the PWM modulator. The resulting PWM output exhibits its duty cycle proportional to the derivative of the input signal. Second, when input signal is applied to the non-inverting terminal of the integrator circuit, the generated PWM signal whose duty cycle is proportional to both input and its integral. To ensure that the generated PWM signal conveys the message correctly, PWM demodulator is used to validate and confirm the results. Therefore, both proposed configurations effectively function as PWM modulators for both information signal and its integral. Finally, the results of in-depth mathematical analysis are validated and align well with all experimental results.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Linear Variable Differential Transformer Signal Conditioning Circuit Based on Phase-Locked Loop
    (2024-01-01)
    Songsuwankit, Kanoknuch
    ;
    Petchmaneelumka, Wandee
    ;
    Riewruja, Vanchai
    ;
    Rerkratn, Apinai
    The 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.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Simple Technique for Linear-Range Extension of Linear Variable Differential Transformer
    (2019-07-01)
    Petchmaneelumka, Wandee
    ;
    Koodtalang, Wittaya
    ;
    Riewruja, Vanchai
    A technique for extending the linear range of a linear variable differential transformer (LVDT) is introduced in this paper. The linear operating range of a commercial LVDT is narrow compared to the full stroke range due to its nonlinear transfer characteristic. The narrow linear range of the commercial LVDT can be extended to maximum stroke range using the proposed technique based on LVDT inverse transfer characteristic. The circuit building block provided the third-order inverse transfer characteristic of the LVDT is established using analog multipliers and operational amplifiers (opamps). The proposed technique requires only commercially available devices, which is attractive in terms of a simple configuration and low cost. Performances of the proposed technique are discussed in detail and confirmed by simulation and experimental results using the commercial LVDT. As a result, the linear range of the LVDT used in this paper can be extended from ±2mm to ±15mm with the maximum absolute error of about 10.23{\mu }\text{m} or the full-scale error of about 0.068%. It is shown that the linear range of LVDT can be extended greater than seven times.