An enhanced half-bridge resonant inverter for induction cap sealing is presented in this research. The proposed method is a combination of a matching transformer, a resonant capacitor, and the series resistance and inductance elements of an induction cap-sealing load. The asymmetrical duty cycle approach is employed to regulate the output power. During the induction cap sealing process, the operating frequency is adjusted automatically through the application of a phase-locked loop control mechanism in order to maintain a steady lagging phase angle between variations in load parameters. The validity of the proposed technique is evaluated using computer simulation, followed by a hardware experiment completed within an operating frequency range of 52.05–53.8 kHz.

This paper presents a compact and accurate readout circuit for remote two-wire resistive sensors, based on an inverting operational amplifier with a fixed bias voltage, diode steering, and unidirectional square-wave excitation generated by a microcontroller. The proposed method determines the sensor resistance by directly sampling two steady-state voltage plateaus at the op-amp output during alternating excitation phases. This approach enables fast, lead-wire-insensitive measurements without the need for analog filtering or precise PWM duty-cycle control. The architecture supports sensor array multiplexing via analog switches, allowing scalable, low-power implementation. Experimental results demonstrate a maximum relative error of 0.23% across a wide resistance range (0.5–3.5 kΩ), confirming the method’s suitability for low-cost, embedded, and remote sensing applications.

This paper presents a microcontroller-based technique for accurately measuring resistive sensors over a wide dynamic range using an adaptive constant current source. Unlike conventional voltage dividers or fixed-current methods—often limited by reduced resolution and saturation when sensor resistance varies across several decades—the proposed system dynamically adjusts the excitation current to maintain optimal Analog-to-Digital Converter (ADC) input conditions. The measurement circuit employs a fixed reference resistor and an inverting amplifier configuration, where the excitation current is generated by one or more pulse-width modulated (PWM) signals filtered through low-pass RC networks. A microcontroller selects the appropriate PWM channel to ensure that the output voltage remains within the ADC’s linear range. To support multiple sensors, an analog switch enables sequential measurements using the same dual-PWM current source. The full experimental implementation uses four op-amps to support modularity, buffering, and dual-range operation. Experimental results show accurate measurement of resistances from 1 kΩ to 100 kΩ, with maximum relative errors of 0.15% in the 1–10 kΩ range and 0.33% in the 10–100 kΩ range. The method provides a low-cost, scalable, and digitally controlled solution suitable for embedded resistive sensing applications without the need for high-resolution ADCs or programmable gain amplifiers.

This paper presents a Class E zero-voltage soft-switching (ZVS) resonant inverter integrated with a CLC filter and a digital resonant frequency tracking technique for driving a piezoelectric ceramic transducer (PZT) in ultrasonic cleaning applications. A digital signal processor (DSP) is used to dynamically monitor and adjust the operating frequency in response to slight variations in the cleaning load, employing a phase-locked loop (PLL) control scheme. The proposed method ensures that the inverter maintains ZVS operation across a frequency range from 30.0 kHz to 34.0 kHz, thereby improving energy efficiency and reducing switching losses. The system is capable of delivering a stable power output of 100 W. Both the simulation and experimental results validate the effectiveness of the proposed technique, demonstrating improved performance under varying load conditions. The combination of CLC filtering and frequency tracking offers a compact and robust solution suitable for ultrasonic cleaner systems and similar resonant-load applications.

This paper presents a simple and effective three-wire configuration for accurate resistive sensor measurement using the Analog-to-Digital Converters (ADCs) of microcontrollers. The proposed method compensates for lead-wire resistance, a major source of error in long-wire sensor installations, without requiring additional analog circuitry or complex signal conditioning. The configuration is based on the Anderson current loop and exploits the internal resistances of microcontroller I/O pins to stabilize the current path. It uses a single ADC with four channels and two digital output pins to control the supply path of the measurement circuit. This architecture simplifies circuit design, reduces component count, and lowers system cost and power consumption. Experimental validation with resistances in the Resistance Temperature Detector (RTD) 1000 range (500–3,500 Ω) confirms high measurement accuracy, achieving a maximum uncertainty of 0.16%. The method is well-suited for practical, low-power, and cost-sensitive resistive sensing applications in embedded and Internet of Things (IoT)-based temperature monitoring systems.