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Development of a Phase-Locked Loop Circuit in Running Frequency Mode for Capacitance-to-Voltage Conversion
(2025-01-01)
On-Khong, Tada
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Sisuk, Noppadon
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Wardkein, Paramote
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Katman, Ratchanoo
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Prompak, Kriangsak
Capacitance-to-voltage conversion is essential for capacitive sensors in various industries, including touch interfaces, medical devices, and moisture measurement. However, circuit design faces challenges like non-linearity, noise, and small capacitance variations affecting voltage signals. This article proposes a phase-locked loop in free-running oscillator mode with a frequency-to-voltage converter to enhance accuracy and stability. Test results show a 97.9% measurement accuracy, demonstrating reduced noise and improved stability. The proposed circuit is ideal for high-precision applications in diverse environments, overcoming limitations of traditional methods.
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DEVELOPMENT OF AN EMBEDDED EXERCISE POSTURE PREDICTION SYSTEM FOR OFFICE SYNDROME USING MACHINE LEARNING
(2024-12-01)
Sisuk, Noppadon
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Onkhong, Tada
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Kaewpoonsuk, Anucha
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Wardkein, Paramote
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Prompak, Kriangsak
Office syndrome is a condition with a high prevalence among people of working age and an upward tendency. In this study, a wearable device implant based on machine learning will be created for exercise of office syndrome. Developing a machine learning model that can distinguish 3 exercise postures for implantable devices was the objective of the study. The Edge Impulse online software was used for data collecting, preprocessing, training, and testing. After that, the model was successfully installed and tested on an Arduino Nano 33 BLE microcontroller. In addition to designing embedded systems, this work also developed applications through the App Inventor program for exercising properly. From testing the system, the model showed an average classification accuracy of 97.6% of exercise postures. The results of testing the embedded system in conjunction with the presented application on 10 subjects showed that the system was able to provide predictive accuracy for wrist exercises, shoulder exercises and stretch exercises with 95%, 97%, and 93%, respectively.
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Ultrasonic Distance Detection Based on Forced Oscillation of Quadrature Oscillator
(2020-03-01)
Sudtana, Sukkan
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Sisuk, Noppadon
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Prompak, Kriangsak
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Keawpoolsuk, Anucha
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Maneegirapragarn, Narongrit
In this article, the detection of distance with ultrasonic wave based on finding travel time forward and backward or time of flight (TOF) with oscillator circuit at the receiver that operates under forced oscillation is proposed. Because of this detection, there is no need for the distance-measuring receiver circuit to use mixer circuit. This is because there are some behaviors of the oscillator and the mixer under the force oscillation. For this proposed system, it consists of And Gate for on-off to transmit ultrasonic signal with 40 kHz frequency. At the receiver, quadrature oscillator circuit is used to be a mixer and local oscillator in a single circuit. So, it causes the proposed circuit is also low complexity and low power consumption.
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Velocity detection by ultrasonic doppler based on multi-time technique analysis
(2019-07-01)
Sudtana, Sukkan
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Prompak, Kriangsak
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Suphramit, Suphawadee
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Sisuk, Noppadon
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Boonjun, Surapol
Experimental result of velocity measuring technique, namely, The ultrasonic Doppler, the technique employs a phase shift oscillator to be combination of signals for mixer replacement and tracks the Doppler frequency, is reported. The received ultrasonic signal was fed to the phase shift oscillator that generate 40.7 kHz of natural frequency as same as transmitted frequency. An output response of received ultrasonic present evidently in Doppler frequency which is proportional to velocity of object. Additionally, The great advantage of the multi-time technique could be used in order to predict its behavior. Measurement results verify the efficacy and agree well with analysis.
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A simple frequency adjustable self-oscillation class D amplifier using OTA
(2014-02-04)
Suklek, Niparat
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Prompak, Kriangsak
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Kaewpoonsuk, Anucha
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Maneechukate, Thongchai
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Wardkein, Paramote
In this paper, a frequency adjustable self-oscillation class D amplifier circuit is proposed, where it can adjust the frequency in the wide band from 50kHz to 500kHz. This proposed circuit uses the feedback principle to compare with the information input signal at hysteresis comparator circuit. The proposed circuit has compact size since it uses only one OTA and one buffer gate. From the experimental results, its THD is in a range 0.75 to 1.59% with the input sinusoidal frequency range from 20Hz to 20kHz. For the frequency response, this circuit can respond well to the audio frequency, i.e., from 20Hz to 20kHz. The proposed circuit can easily adjust the frequency of the selfoscillating circuit by tuning the resistors in circuit. From the experimental result, this proposed circuit corresponds well with the principle and the analytic theory. © 2014 ISSN 1881-803X.
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Flow rate controlling using phase-locked loop
(2013-03-28)
Prompak, Kriangsak
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Kaewpoonsuk, Anucha
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Maneechukate, Thongchai
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Phanphaisarn, Wasu
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Wardkein, Paramote
This paper proposes controlling flow rate by using Phase-Locked Loop (PLL) to control the voltage output of power amplifier sent to the DC pump. With this technique, the flow rate of liquids in the pipe connected to such pump can be easily adjusted. With the property of PLL, the frequency of output signal of the flow sensor, which is proportional to the flow rate, is synchronized with that of the reference input. As a result, the flow rate remains constant. In addition, the experiment results show that the flow rate is not affected by the varying loads, i.e., the flow rate is stable to perturbations. © 2013 ICIC International.

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