https://matjournals.net/engineering/index.php/JDCIED en-US Journal of Digital Circuitry Innovations in Electrical Devices https://matjournals.net/engineering/index.php/JDCIED/article/view/3803 <p><em>As the world is shifting to EV transportation, the requirement for charging methods that are fast, efficient, and do not wear out batteries too quickly is also rising. Different approaches exist, and each has its own set of trade-offs. Some prioritize speed, others focus on battery health, and a few try to balance both. The proposed system dives into the design and simulation of a lithium-ion battery charging system for electric vehicles. This paper presents the design and simulation of a DC-DC boost converter stepping up the voltage from 12V to 16.8V for a 4.5Ah battery pack. Boost converter parameters, including inductor, capacitor, and switching device, are designed for continuous conduction mode operation at a specified switching frequency. A proportional-integral (PI) controller employing negative feedback control regulates the constant-current-constant-voltage charging by sensing battery current and computing the duty cycle. Simulation is carried out using MATLAB Simulink to observe the ripple voltage spikes across the output voltage by changing the switching frequency. Results show us that 35 KHz provided the least ripple voltage compared to other frequencies on which the system was tested.</em></p> Prathamesh Padamwar Ashok Suryawanshi Ganesh Rahate Arnav Bhawat Copyright (c) 2026 Journal of Digital Circuitry Innovations in Electrical Devices 2026-07-01 2026-07-01 2 2 1 11 https://matjournals.net/engineering/index.php/JDCIED/article/view/3810 <p><em>Modern smartphone-based Point-of-Sale (POS) systems and digital accounting applications have significantly improved financial transaction management in urban commercial sectors. However, many rural and small-scale MSMEs continue to face challenges due to expensive hardware, unstable internet connectivity, limited digital literacy, and a lack of accessible accounting solutions. Traditional calculators remain affordable and easy to use, but they lack transaction logging, GST computation, analytics, customer due management, or secure record storage. To address these limitations, DigiCal was developed as a smart embedded business calculator specifically designed for offline financial inclusion and digital transformation of MSMEs. </em><em>T</em><em>he proposed system combines the familiarity of a conventional calculator with advanced business functionalities, including automated GST calculation, transaction storage, customer due management, expense tracking, sales analytics, and financial reporting. DigiCal follows an offline-first architecture, using a lightweight SQLite database for secure local storage, while also supporting optional cloud synchronization and web-based analytics when network connectivity becomes available. The hardware implementation is based on a Raspberry Pi Zero 2W integrated with a custom 5×7 matrix keypad, TFT display, rechargeable battery system, speaker feedback module, and lightweight Python software architecture. Experimental evaluation demonstrated reliable real-time transaction processing, stable offline operation, accurate GST computation across multiple tax slabs, responsive user interaction, and efficient local data management. The system also exhibited low power consumption and dependable transaction storage under practical operating conditions. By combining affordability, portability, and ease of use, DigiCal provides a practical alternative to expensive POS systems while preserving the simplicity of traditional calculators. The proposed platform can support improved financial record management, operational efficiency, and sustainable business digitization, thereby contributing to greater financial inclusion for MSMEs operating in low-connectivity environments.</em></p> Atharva Gawali Kalpit Jare Yash Nayyar Jyoti Botkar Copyright (c) 2026 Journal of Digital Circuitry Innovations in Electrical Devices 2026-07-02 2026-07-02 2 2 12 24