Luka Đorđević

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Personal Engineering projects

Experimenting with passive exoskeleton:This was a casual and simple project. I wanted to see if using a simple configuration of elastic tubing, steel cable, could be used to make a passive exoskeleton for the purpose of alleviating load on the knees. I didn't have the resources to do rigorous testing, but a proof of concept prototype was made. [Spring of 2022]

Concept 3D model.

Prototype demonstration.

Homemade CO2 laser cutter:
A diy laser cutter fully designed and built by me. While the enclosure and fume extraction systems were never completely finished, the laser cutter is functional and was a great learning experience. It's my first larger and mostly finished project. [Summer of 2022]

Full assembly modeled in fusion 360

Initial assembly of laser cutter in my room.

Example product I made with the laser cutter.

Brushless DC motor driver:
Simple BLDC driver I made shortly after acquiring my first analog oscilloscope. It was mainly an educational project and for that reason I used discrete N-MOSFETs as switching elements and I made the bootstrapping circuits used for high side switching. While limited in speed, it's a functional motor driver that fulfilled the main design goals - making the motor spin and having adjustable speed. [Spring 2023]

Video demonstrating BLDC driver functionality.

PWM generator with bootstrap MOSFET driver:
This project was something I worked on during a misguided attempt at making a curve tracer, intended for use in a switching mode power supply, creating a PWM signal whose duty cycle was proportional to a supplied input voltage (0-5V). The idea was that it would allow for high frequency switching (in the 300-500kHz range) in the power supply, that is controlled by a microcontroller that can't create a PWM signal of that high of a frequency. This circuit is what I ended up writing a paper about for the IEEESTEC student conference at the Niš Faculty of Electronic Engineering, as I wasn't able to complete a regulated SMPS in time. [Autumn 2023]

Taking oscilloscope measurements of the square wave output.

*SEPIC converter with analog control circuit:
Shortly after the day of the aforementioned conference I successfully implemented the PWM generator along with a few operational amplifiers to create a fully analog self regulating DCDC converter, whose voltage is set using one potentiometer. I made a miniature cuk converter as a source of negative voltage, and a triangle wave generator which was part of the initial PWM generator circuit. I never ended up properly writing a paper on this device, but I got to present my work at the Petnica Science Center's conference "A Step Into Science". [Winter 2023]

Triangle wave generator (left) and cuk converter (right).

Improved version of the SEPIC converter, this time with a proper MOSFET gate driver IC.

Picture taken during testing.

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Professional experience

3D printing gigs:
I have provided a 3D printing and assembling service, making decorative elements and miniatures for painting workshops, for Sport Vision - a company specializing in sports equipment. [Spring-Winter 2022]

3D printed shoe after painting workshop

Decorative elements for the photo booth

Electronics Teacher - little school of electronics:
Having attended classes at the little school of electronics when I was a child, I was thrilled to have a chance to work there. I was in charge of holding the classes for children ages 6-13 using a practical approach to guide them through electronics, from simply turning on an LED, to using integrated circuits to assemble a 7-segment display counter. [Spring 2023 - Fall 2024]

Junior Teaching Associate - Petnica Science Center:
The Petnica Science Center hosts many seminars, held in 3-4 sessions per year, primarily for high school students but also for 8th graders and college students. I participate in the organization of the Electronics Seminar and the Petnica Summer Science School as a junior teaching associate - I act as a mentor for a section of the papers written during our seminars, prepare lectures and lab exercises on fundamental topics in electrical engineering, and am there to answer any questions as well as to ensure our attendees are safe and comfortable. [August 2024 onwards]

The team reviewing final presentations of the attendees

Helping an attendee with lab measurements

Student Associate - Hamburg University of Technology:
I'm in charge of holding a monthly soldering workshop at the WorkING lab at the Hamburg University of Technology. The general concept is "for students by students", and during my workshops I get to share my knowledge of soldering with my fellow students, in whatever form I think is best. During my workshop the attendees get to solder many different components in different packages on a PCB I designed, after which they are left with a fun circuit board that blinks red and green, and can be played like a keyboard. Other than holding the workshops themselves my tasks include keeping track of our stock of parts and making sure we have enough at all times. [April 2025 onwards]

Helping an attendee test their board while others are still soldering.

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Academic work and publications

High Frequency PWM Generator and MOSFET
Bootstrapping Circuit - IEESTEC 2023, Niš Faculty of Electronic Engineering:
This was the first paper I wrote, and it covers the functioning principles of, as the name says, a high frequency PWM generator and MOSFET bootstrapping circuit I developed and tested.

Automatic Regulation of SEPIC Converter - A Step Into Science 2023, Petnica Science Center:
During this conference I was able to present my work in developing an analog voltage regulator for a SEPIC DCDC converter as part of the Electronics Seminar. It was a chance to learn from others, share my own knowledge, and make my first conference poster.