Journal of Electronics Design and Technology

Design and Implementation of a Face Recognition Door Lock System Using Raspberry Pi

Neha Janardan Naukudkar — 2026-01-31

Security is a major concern in residential, commercial, and institutional environments. Conventional door locking mechanisms such as mechanical keys, passwords, and RFID cards suffer from limitations including loss, duplication, and unauthorized access. To address these challenges, this paper presents the design and implementation of a face recognition-based smart door lock system using Raspberry Pi. The system utilizes computer vision techniques to identify authorized individuals and control a solenoid-based door lock. Facial images are captured using a camera module and processed using the local binary pattern histogram (LBPH) algorithm for face detection and recognition. Raspberry Pi serves as the central controller for image processing, decision-making, and hardware control. The system also provides user feedback through an LCD and optional voice assistance. Experimental results demonstrate reliable access control, enhanced security, and cost-effective implementation, making the system suitable for smart homes and secure premises. In addition, the proposed system emphasizes ease of use and scalability by allowing new users to be enrolled on the database with minimal effort. The use of open-source software libraries and affordable hardware components ensures low implementation cost while maintaining acceptable accuracy and performance. The face recognition approach eliminates the need for physical credentials, thereby reducing the risk of theft or misuse.

Design and Development of a Low-cost ESP32-based Quadruped Spider Robot

Premprakash Sharma — 2026-03-02

Legged robotic systems have garnered significant attention for their ability to operate in unstructured and uneven environments, where traditional wheeled robots face mobility limitations. Inspired by biological locomotion, quadruped robots offer enhanced stability and adaptability through multiple points of ground contact. This study presents the design, development, and experimental evaluation of a low-cost quadruped spider robot capable of stable and coordinated legged locomotion using an embedded control platform. The proposed system is based on an ESP32 microcontroller, which performs real-time control and wireless communication. Each leg is actuated by three servo motors corresponding to the hip, knee, and foot joints, resulting in a twelve-degree-of-freedom configuration that enables smooth and synchronized motion. Bluetooth communication is employed to allow real-time command input from a mobile device, ensuring flexible and intuitive control. A diagonal alternating gait algorithm is implemented to achieve stable locomotion by dividing the legs into support and swing phases, thereby maintaining balanced weight distribution during movement. Precise servo actuation is achieved using a dedicated PWM servo driver module, which reduces computational overhead on the microcontroller. The robot structure is fabricated using lightweight materials to minimize power consumption and mechanical stress. Experimental evaluation under controlled conditions demonstrates stable walking behaviour, reliable wireless response, and smooth joint coordination. While minor limitations in load capacity and locomotion speed were observed due to actuator constraints, the overall performance validates the feasibility of the proposed system. The developed platform serves as an effective testbed for embedded gait control and provides a foundation for future enhancements such as autonomous navigation and adaptive locomotion.

T-Flip-Flop Implementation using Quantum-dot Cellular Automata

Kazi Kutubuddin Sayyad Liyakat — 2026-03-27

The unrelenting pursuit of sub-nanometer circuits has generated a great deal of interest in non-traditional computing paradigms that can outperform CMOS in terms of scaling. A promising path to ultra-low-power, ultra-dense logic is provided by Quantum-dot Cellular Automata (QCA), a charge-based nanotechnology that encodes binary information in the polarisation of electrostatically connected quantum dots. This work describes a novel T (Toggle) Flip-Flop that is fully QCA-implemented, which combines the special limitations of QCA fabrication with the strict requirements of sequential logic. Starting with a compact majority-gate-based T-gate, it designs a clock-zone-synchronised latch that achieves dependable toggling behaviour by combining wire-crossing, clock-phase inversion, and a four-dot majority cell. Comprehensive cell-level simulations in the QCADesigner environment, examining both the coherent (adiabatic) and quasi-adiabatic clocking regimes, are used to validate the suggested circuit. State-of-the-art QCA Flip-Flops and traditional CMOS implementations are compared to key performance measures, such as area, energy dissipation, cell count, and layout footprint. In comparison to the best-reported QCA latch, this studies show that the QCA T-Flip-Flop not only reduces area by 70% and energy consumption by 45%, but it also maintains robust functioning despite realistic process variations (±10% cell size, ±5% inter-dot spacing). The study demonstrates that it is possible to directly insert sequential elements into QCA nanocircuits, opening the door for fully QCA-based micro-architectures and finite-state machines.

Comparative Analysis of Miller Effect in RC-Coupled, Transformer-Coupled, and Direct-Coupled Amplifier Stages

ASM Shamim Hasan — 2026-03-30

This study presents a comprehensive experimental and simulation-based comparative analysis of the Miller effect in three widely used amplifier configurations, RC-coupled, transformer-coupled, and direct-coupled BJT amplifier stages. The Miller effect significantly influences high-frequency performance by increasing the effective input capacitance through internal feedback. In this work, both hardware experimentation and LTspice simulations were performed under identical biasing and operating conditions to ensure consistency. Key parameters such as voltage gain, effective input capacitance, and upper cutoff frequency were evaluated. The results show strong agreement between experimental and simulation data. The direct-coupled amplifier exhibits the highest Miller multiplication and lowest bandwidth, while the transformer-coupled amplifier demonstrates superior high-frequency performance due to reduced effective capacitance. The RC-coupled amplifier provides a balanced trade-off. This study provides practical insights for selecting appropriate coupling techniques in high-frequency analogue circuit design.

Personal Autopay System: A Comprehensive Framework for the Automation of Recurring Digital Payment Transactions

Agilesh N. V. — 2026-04-03

The Personal Autopay System is a technology platform intended for the automation of financial transactions, which include the payment of bills, subscription services, insurance, and loan repayments. In today’s financial environment, it is common for individuals and organisations to have several financial transactions, which can be processed periodically. The use of autopayment systems has been a solution to the challenges associated with the processing of financial transactions. The system has been enhanced in recent times through the integration of Artificial Intelligence (AI) and blockchain technology. The integration of AI technology has enabled the prediction of potential failures in financial transactions. The autopayment system has also been enhanced through the integration of multiple financial instruments, which can be used in the processing of financial transactions. The paper will cover the architecture of the system, the workflow of the system, the main features of the system, security aspects of the system, advantages of the system, applications of the system in different industries such as banking, power, education, insurance services, etc., disadvantages of the system, and prospects of the system including aspects of AI, Cloud Computing, IoT, etc. It is to be noted that the use of Personal Autopay Systems will greatly benefit the overall efficiency of digital financial transactions.