Pulse width modulation (PWM) is used to generate pulses with variable duty cycle rate. The rapid rising and falling edges of PWM signal minimises the switching transition time and the associated switching losses. This paper presents a DC motor speed controller system using PWM technique. The PWM duty cycle is used to vary the speed of the motor by controlling the motor terminal voltage.The motor voltage and revolutions per minutes (RPM) obtained at different duty cycle rates. As the duty cycle increases, more voltage is applied to the motor. This contributes to the stronger magnetic flux inside the armature windings and the increasethe RPM. The characteristics and performance of the DC motor speed control system was investigated. In this paper, a PIC microcontroller and a DC-DC buck converter are employed in the DC motor speed controller system circuit. The microcontroller provides flexibility to the circuit by incorporating two push button switches in order to increase and to decrease the duty cycle rate. The characteristics and performance of the motor speed controller system using microcontroller was examined at different duty cycle rate ranging from 19% to 99%.

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In this paper, the design of a wideband width impedance matching topology for Power Amplifier (PA) applications has introduced. The design topology has implemented with single, double and triple stages to demonstrate the wideband width frequency range for input and output matching network section of the PA amplifier. Each stages of the proposed matching circuit has LC filter with high and low pass design configuration. The single stage configuration provides the wide band frequency of 1.07 GHz to 2.094 GHz at-74 dB gain. The frequency range of-0.75 GHz to 2.95 GHz has obtained in double stage configuration with-28 dB, 40 dB gain. The triple stage offers a wide frequency range of 0.59 GHz to 3.7 GHz with-17 dB, 96 dB,-55 dB and-30 dB gain at the cut off frequency of 1.5 GHz which is suitable for PA applications.

This project mainly focuses on an autonomous assistive robot for healthcare application that is developed to dispense medications to the individual patients in the patient care facility. This autonomous line-follower robot is able to detect and follow the line drawn on the floor while driving through the facility with the ability to stop when it faces obstacles. The source of energy supply to the whole robot is fed from the power supply through the ESP32 microcontroller that is programmed using C++ with infrared sensors connected to the board for sensing the drawn line. The ultrasonic sensors are used to detect any obstacles on their way and put the robot at a halt condition with an alarm indicating the obstacle occurrence. The robot will stop at the junction to dispense the medicine for 10 seconds before proceeds to the next station. After the medicine has been dispensed, a confirmation message will be sent out from CallMeBot API in Telegram to acknowledge the medical staff on the successful delivery of the medicine to each patient. The result presented the experimental data on the path line application and the obstacle detection to demonstrate the efficiency of the application.