Alec Christov

Project Overview

This project was my introduction to practical electrical engineering. I designed and built a complete electric bike from the ground up, including a custom lithium-ion battery pack that required careful cell selection, balancing, and protection circuit design.

Key Achievements

• Designed and assembled a custom lithium-ion battery pack using 18650 cells
• Implemented battery management system (BMS) for safe charging and discharging
• Sourced and integrated a brushless hub motor and motor controller for the drive system
• Solved mechanical integration challenges for battery mounting and wiring routing
• Achieved reliable performance for daily commuting use

Skills Developed

• Lithium battery pack design and assembly
• Battery management system integration
• High-current wiring and connector selection
• Motor controller selection and system integration
• Power electronics fundamentals
• Hands-on problem solving and iterative design

Technical Details

The battery pack was designed with careful consideration of cell capacity matching, thermal management, and protection against overcharge, overdischarge, and overcurrent conditions. The motor and controller were sourced commercially and integrated into the system. This project taught me the fundamentals of power electronics that I've applied throughout my subsequent work.

Project Overview

A high-power project involving the repurposing of microwave oven transformers (MOTs) to create a metal melting rig capable of melting small quantities of metal through resistive heating.

Key Achievements

• Successfully rewound microwave transformer secondary for high-current, low-voltage output
• Designed safe switching and control circuitry for high-power operation
• Implemented thermal management solutions for sustained operation
• Achieved sufficient power output to melt aluminium and other metals

Skills Developed

• Transformer theory and practical rewinding techniques
• High-current circuit design and safety considerations
• Thermal management for high-power applications
• Safe handling of dangerous voltages and currents

Technical Details

The project involved removing the original secondary winding from MOTs and replacing it with a few turns of heavy gauge cable to achieve very high currents at low voltage. This required understanding of transformer principles, wire gauge selection for current capacity, and careful attention to electrical safety.

Project Overview

A complete standalone photovoltaic power system featuring a custom-designed PCB for power management, battery charging, and Wi-Fi-enabled monitoring. The system manages power flow between solar panels, battery storage, and loads.

Key Achievements

• Designed custom PCB for three-port power management (solar, battery, load)
• Implemented MPPT or PWM solar charge control
• Integrated Wi-Fi microcontroller for remote monitoring and data logging
• Created power sensing circuits for voltage and current monitoring
• Developed complete standalone system requiring no grid connection

Skills Developed

• Multi-port power management architecture
• Solar charging circuit design
• IoT/Wi-Fi embedded system integration
• Sensor integration for power monitoring
• PCB design for power electronics

Technical Details

The custom PCB handles the complex task of managing power flow between three ports while monitoring system health. The Wi-Fi capability enables remote access to system data, making it possible to monitor performance and diagnose issues without physical access to the installation.

Project Overview

Development of custom lithium-ion charging circuit boards designed for safe and efficient battery charging across multiple personal projects. These boards implement proper CC/CV charging profiles and protection features.

Key Achievements

• Designed multiple charging circuits for different cell configurations
• Implemented proper CC/CV (Constant Current/Constant Voltage) charging profiles
• Integrated protection features for overcharge, overdischarge, and overcurrent
• Optimised for efficiency and thermal performance
• Created reusable designs for future projects

Skills Developed

• Lithium battery charging theory and implementation
• Charging IC selection and application circuit design
• Protection circuit integration
• Thermal design for charging applications
• PCB layout for power applications

Technical Details

Each charging circuit was designed with careful attention to the specific requirements of lithium-ion chemistry, including proper termination voltage, charge current limits, and temperature monitoring. The designs balance charging speed with battery longevity and safety.

Project Overview

An ongoing project to design and build a dual-resonance steady-state Tesla coil (DRSSTC). This project explores high-voltage RF design, resonant circuit theory, and power electronics at the advanced hobbyist level.

Current Progress

• Researching DRSSTC topology and control strategies
• Designing primary and secondary coil geometries
• Selecting components for the H-bridge driver
• Planning feedback and interrupter circuits

Skills Being Developed

• High-voltage design and safety
• RF and resonant circuit theory
• H-bridge and gate driver design
• Coil winding and tuning techniques
• EMI considerations and mitigation

Technical Approach

The DRSSTC approach uses solid-state switching (IGBTs or MOSFETs) to drive the primary coil at its resonant frequency, with feedback from the secondary ensuring the system stays in tune. This allows for controlled, repeatable operation compared to spark-gap designs.

Project Overview

A variable DC lab bench power supply capable of 0-30V output at up to 5A continuous current. Built as a practical tool for electronics work, featuring digital voltage and current display with adjustable limits.

Design Source

This build follows the design from this YouTube tutorial. The original designer deserves full credit for the circuit design and build instructions.

Components Used

• AC-DC Power Supply: 36V 5A 180W Switching Power Supply
• DC-DC Converter: 0-30V 5A Buck-Boost Converter with digital display
• Output: Banana plug binding posts
• Control: 3-pin On-Off-On switch
• Input: 5.5mm DC jack
• Cooling: 80x10mm 12V fan
• Other: Various salvaged parts from old electronics

Skills Practiced

• Following technical build instructions
• Component sourcing and procurement
• Enclosure fabrication and layout
• Wiring and assembly of power electronics
• Testing and verification of output specifications
• Salvaging and repurposing components

Why I Built This

A quality bench power supply is an essential tool for any electronics workbench. Building one from a proven design was a practical way to get a reliable tool while gaining hands-on experience with power supply components and assembly techniques.

Project Concept

The goal was to explore small-scale renewable energy generation by repurposing an electric bike hub motor as a wind turbine generator. Hub motors can function as generators when mechanically driven, making them an attractive option for DIY wind power projects.

Approach

• Repurposed an electric bike hub motor to act as a generator
• Designed and fabricated turbine blades
• Built an aluminium frame to mount the assembly
• Planned rectification and charging circuitry for battery storage

Why It Failed

The aluminium frame and hub motor assembly proved too heavy for practical wind turbine use. The high rotational mass required wind speeds that were rarely available at ground level, and the structural requirements for supporting the weight made the project impractical for a small-scale installation.

Lessons Learned

• Weight matters: Wind turbine design requires careful attention to rotational mass and cut-in wind speed
• Feasibility first: Should have calculated power output vs. weight ratio before building
• Hub motors aren't ideal: Purpose-built generators or lighter alternator designs are better suited for wind applications
• Site assessment: Average wind speed at the installation site is critical to evaluate early

Skills Developed

• Understanding of generator/motor duality
• Renewable energy system fundamentals
• Mechanical fabrication with aluminium
• Project feasibility analysis (learned the hard way)
• Knowing when to discontinue a project

Takeaway

Not every project succeeds, but every project teaches something. This experience reinforced the importance of feasibility analysis and calculating key parameters before committing to a full build. The lessons learned here have informed my approach to subsequent projects.

Role Overview

Electrical design engineer on a confidential electronics development program. My public description is limited to how I worked: translating requirements into electrical engineering tasks, supporting design iterations, validating prototypes, and preparing documentation for manufacturing conversations.

Public Scope

Because the project is protected, product function and design choices remain private. The shareable work centred on engineering judgement, disciplined documentation, prototype bring-up, issue tracking, and communicating trade-offs with the team.

Tools & Technologies Used

• ECAD: Fusion 360 Electronics, Altium Designer
• Lab Work: Oscilloscopes, multimeters, soldering, and rework equipment
• Documentation: BOM, procurement, revision notes, and assembly outputs
• Workflow: Design reviews, prototype testing, and manufacturing preparation

Engineering Work Performed

• Requirements review and engineering task breakdown
• Component research and comparison without sharing part choices
• Schematic capture and PCB layout workflow
• Prototype assembly coordination and bring-up support
• Test planning and measurement-driven debugging
• Revision tracking and design review notes
• BOM and assembly package preparation