- About me -

vladimir

Vladimir Zhelezarov

  • born 1980 in Bulgaria;
  • long time ago worked in my own small company, specialized in industrial cleaning and antigraffiti;
  • living in Germany since 2012;
  • for ~7 years (2015-2021) worked as a service technician for wind turbines in "Deutsche Windtechnik AG" - mainly BONUS/ Siemens. This led to some fun and challenging private side projects (see below);
  • in 2022 aquired a bachelor degree in "Digital Engineerring and Applied Computer Science" from AKAD University;
  • passionate about learning new things and solving real world problems.

    - Portfolio -

    analog to digital bridge

    A fully transparent, bidirectional Analog-Digital Bridge for Siemens/BONUS wind turbines

    Intelligent management of the turbine hub's signals.

    • stable and (in the case of the old BONUS turbines) more reliable Bluetooth connection;
    • translate all signals to digital, transmit and then recreate them on the other side;
    • watch every single signal and log all errors on a SD card;
    • a very extensible software, allowing to watch for much more complicated conditions;
    • enormously reducing the costs of repairing a slippery ring;
    • enormously reduction in time when searching for a problem's cause;
    • the error log can be read directly from the SD, or through an Android app.

    Browse the circuit plans and the code on github

    view at github  

    Tags:  C, Microcontroller, Wind Turbines, Open Source

    Last modified: 08.07.2018


    Bluetooth Display

    A bluetooth interface and Android app for Siemens/BONUS wind turbines

    The service technician will fall in love with it because of its effectiveness, the CEO will fall in love with it because of its cost.

    • every possible function of the original controller, but without the cable;
    • a -lot- additional features like phone call, taking and organizing pictures and notes, access to circuit diagrams, flashlight ...
    • secure two-way authentication, encrypted connection, dynamic keys;
    • macros - preprogrammed sets of repeatable actions, like starting a pump with a single click;
    • extensible framework, adaptable to much more wind turbines than BONUS;
    • a fraction of the cost of the original controller;
    • source code now available at GitHub

    Browse the code on github or view it in action on a 2MW AN-BONUS (Siemens) WTC2 wind turbine:

    view at github  

    youtube video  

    Tags:  C, Java, Android, Microcontroller, Wind Turbines, Open Source

    Last modified: 05.05.2019


    Serial-to-Bluetooth interface

    Advanced, programmable RS485 interface

    Originaly created as the hardware companion to BTDisplay, but then evolved to general purpose programmable interface.

    • fully programmable functions thanks to the integrated ATMEGA microcontroller;
    • industrial grade components with lot of redundance;
    • really small form factor;
    • general purpose LED, recharchable battery with charging circuit, magnet;
    • open-source hardware.

    view at github  

    Tags:  Hardware, CAD, Electronics, Wind Turbines, Open Source

    Last modified: 17.10.2017


    VCU monitor

    A low-tech error logging facility for the VCU*

    Quickly troubleshoot VCU-errors

    • The centrifugal switches are connected in series, which is often problematic when troubleshooting. In almost all cases, the problem is a loose connection, which sporadically works.
    • I suggest a simple, non-invasive, low-level and low-cost concept to save the error-events in a mechanical way.
    • The "logger" in the simulation is a bi-stable relay, like this one. The trivial circuits for the reporting and the resetting side are not shown in the simulation.
    • All combinations of error-states are possible, up to the scenario when A and C disconnect simultaneously and then stay disconnected. Then there would be also the (false) report of "B disconnected".

    *Vinge Centrifugal Unit (Overspeed protection switches in the hub)

    Live simulation with all three blades on Falstad (play with the switches to simulate different cases):

    view at Falstad

    Tags:  Wind Turbines, Simulation, Open Source

    Last modified: 13.09.2019


    hydraulics simulation

    Reverse-engineering the hub hydraulics of a popular Siemens/BONUS wind turbine

    To help the service-technician have a better and deeper understanding on what he is working with.

    • real-time simulation with everything adjustable;
    • both electrical and mechanical componets simulated;
    • able to simulate failure-conditions.

    The names of the components in the video are blurred on purpose.

    youtube video  

    Tags:  Hydraulics, CAD, Simulation, Wind Turbines

    Last modified: 04.09.2017


    wind turbines navigation app

    Navigation app using google-maps and simple database

    To quickly find the exact coordinates of a specific wind turbine.

    • search in all database fields as-you-type;
    • work with precise locations;
    • driving directions in real time with google maps;
    • updatable database.

    View the source code at github or see the app in action on youtube:

    view at github  

    youtube video  

    Tags:  Android, Java, Navigation, Wind Turbines, Open Source

    Last modified: 09.09.2017


    steganography tool

    A steganography tool wich features compression, encryption and (almost) non-intrusive hiding techniques.

    Stide uses steganography (hiding secrets in images) and encryption to makes detection and reading of secret messages very difficult.

    • a very low impact on the host image;
    • randomized distribution of the embedded text;
    • the hidden message is additionally encrypted;
    • provided one uses some unique image only once, the output can be compared to a one-time-pad i.e. unbreakable;
    • linux/Windows binaries and simple gui interface included;
    • There are, however, some limitations.

    view at github  

    youtube video  

    Tags:  C, Steganography, Encryption, Open Source

    Last modified: 27.01.2018


    exercism profile

    A platform* to level up in over 30 different languages

    I really liked this portal*, so I joined and:

    • solved every available problem in C;
    • reviewed* as much as possible other solutions;
    • contributed to the site with implementing 15 new exercises, from the available specifications;
    • even build a python tool to automate as much as possible while creating new exercises.

    * exercism.io changed the interface since.

    Visit the site or view my commits in GitHub:

    github repo  

    visit the site

    Tags:  C, Open Source

    Last modified: 22.03.2018


    KR Cover (image from wikipedia.org)

    The C programming language by Brian Kernighan and Dennis Ritchie | Exercises

    My solutions to all exercises from the iconic book on C.

    • Single-file solutions, compile- and test-ready;
    • balanced towards simplicity, without sacrificing too much flexibility;
    • all solutions are based only on the already learned stuff in the current/previous chapters;
    • every file can compile and run with no special dependencies (except some standard library headers);
    • all compiled with: gcc -g -std=c99 -Wall -Wextra -pedantic-errors

    View the solutions at GitHub:

    view at github  

    Tags:  C, Open Source

    Last modified: 01.01.2018


    xsl for vlzware.com

    The template and the scripts I use for this website

    This website was initially meant as a simple placeholder for the projects from FreeCodeCamp, however with the growing number of other projects it became tedious to maintain

    • I wanted to avoid content management system, because it would be an overkill;
    • The same applies to using a database;
    • The solution: use a simple XML template, store every project in a separate file, then combine and transform with XSLT;
    • A Bash script combines all the single files into one for every language;
    • A Python script (using lxml) produces the end result using the transformations, defined in the XSL file;

    All the interesting files are in GitHub:

    view at github  

    Tags:  XML, XSLT, Bash, Open Source

    Last modified: 03.06.2022


    boom-music

    A funny website to create and play music

    Originally created with Boomwhackers in mind, but can be used for almost any kind of music.

    • predefined melodies, which are even editable;
    • create new song from scratch;
    • download your work when ready and upload it later to use it again;
    • a fun family side-project.

    view at github  

    visit boom-music

    Tags:  HTML, CSS, JavaScript, Open Source

    Last modified: 14.09.2019


    Simon Game

    Another fun game from the childhood

    A Simon game:

    • Test your memory in an ever increasing difficulty;
    • Follow the pattern created by the computer
    • You can win after repeating the last sentence of twenty steps;
    • Use strict mode for even more challenge - if you fail, the game will start over.

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 01.11.2017


    TicTacToe Game

    The fun game from the childhood

    TicTacToe game:

    • Play with a friend or against the computer;
    • The AI is a perfect player - you are welcome to try to beat it, but the best one can achieve is a draw;
    • The AI uses the minimax algorithm and chooses a random move from a set of good ones;
    • The game keeps track of all moves.

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 01.11.2017


    pomodoro clock

    A simple but effective management method to boost your productivity

    The Pomodoro technique:

    • Decide on the task to be done.
    • Set the pomodoro timer (traditionally to 25 minutes).
    • Work on the task until the timer rings.
    • After the timer rings put a checkmark on a piece of paper.
    • If you have fewer than four checkmarks, take a short break (3–5 minutes), then go to step 2.
    • After four pomodoros, take a longer break (15–30 minutes), reset your checkmark count to zero, then go to step 1.

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 01.11.2017


    calculator

    Intelligent Calculator

    supporting advanced synthax:

    • build as a pre-parser on top of math.js;
    • supporting parentheses, memory variable, square root, power of two, percent;
    • parse-as-you-type error checking.

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 01.11.2017


    twitch api

    Follow your favorite streams on twitch.tv

    in a quick and effective way:

    • see who is on-/offline and go to their stream on twitch.tv
    • if anyone is streaming see what they are streaming;
    • save your current list of favorites and use it again the next time;
    • search for channels/streams as-you-type.

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 16.09.2019


    wikipedia viewer

    An interface to wikipedia

    Search in wikipedia.org

    • search as-you-type or see a random article;
    • the app shows the top (12) articles with short info and pics if available;
    • click on a header in the results to go to the wikipedia's article.

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 01.11.2017


    show the local weather

    Short weather info

    featuring:

    • browser- or IP-based geolocation;
    • get some basic info;
    • click on the city to get to the nearest weather station.
    • switch between F° and C° by clicking on them.

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 15.09.2019


    random quote machine

    Query wikiquote.org for a random quote

    Features:

    • Clicking on "reload" loads new random quote and the passing image if available;
    • you can tweet the quote if you like

    visit the website

    Tags:  HTML, CSS, JavaScript, FreeCodeCamp

    Last modified: 01.11.2017


    Intelligent measurements

    A self-calculating measurements form

    Solving a big real problem for a small real company.

    • massive reduction in time to process the data from the worker on-site to the customer;
    • the form calculates everything, including finding the right formula, on its own;
    • error checking;
    • on-site measurements with your smartphone only;
    • customer-ready form after a quick copy-paste in an Excel-spreadsheet

    view at github  

    Tags:  Process Optimization, Forms, Open Source

    Last modified: 18.10.2018


    concept for a device without IP

    Plug-And-Play network device for quick and easy deployment of a server/filter in an arbitrary network

    To be used between two other devices for content filtering or to use server software

    • It is possible to use an already available IP-Address twice through virtualization;
    • It does not matter if the network uses DHCP or static settings;
    • The new device is undetectable, without explicit targeted search;
    • It starts as a fully-transparent network bridge, observing and analyzing data;
    • The device calculates all the data it needs to work in the network fully atomatically;
    • After switching to a full-mode-operation all network activities are possible;
    • To show one possible usecase scenario we install PiHole - a DNS-Filter;
    • A connection on the edge of a network offers the most possibilities: data filter, firewall, external access, etc.
    • The original repository with my bachelor thesis (in german) is here.

    The development of this project continues in a separate repository on github:

    view at github  

    Tags:  Networks, Virtualisation

    Last modified: 05.07.2022


    mixed voice recognition

    Privacy focused combination of On- and Offline Voice Recognition

    Controlling the Alexa Software with an offline Hardware

    • Alexa is very powerfull voice recognition, and there is an open-source SDK available;
    • There is no need to record and send audio constantly to Amazon - lot of tasks are just to control home devices;
    • Therefore, for local tasks we use EasyVR - an offline voice recognition hardware:
    • The offline board is very limited, but can handle some trivial tasks;
    • For more complex tasks we call the Alexa Software;
    • There are some limitations*

    *The EasyVR performs very poorly; The Alexa SDK does not have all the features of an "real" Alexa.

    View the source code and documentation (in german) at GitHub or view a simple showcase at Vimeo:

    view at github  

    vimeo video  

    Tags:  Voice Recognition, C++, Python, Hardware

    Last modified: 20.02.2021


    view at github

    Multifunktional Load-and-Shift Register in VHDL

    test-benchmark inclusive

    • Use as a serial/parallel converter;
    • Use as a shift register;
    • Use as a memory unit;
    • Use as a FIFO buffer;
    • Chainable.

    The documentation (in german) and the VHDl files are available on github:

    view at github  

    Tags:  FPGA, VHDL, Open Source

    Last modified: 04.10.2020


    view at github

    PHP/SQL-based forum with all basic features

    • Admin account with full access to add/remove/change/lock other accounts or lock/delete threads;
    • Session-based logins;
    • Ability to make new threads, write new posts and eventually change them afterwards;
    • Working preview available (see below)*
    • Now with updated input sanitization

    *Contact me if you need an account to play arround.

    Visit the forum or view the source code and the documentation (in german):

    view at github  

    Forum

    Tags:  PHP, SQL, Hosting, Open Source

    Last modified: 16.07.2022


    running lights

    App-controlled running lights

    Reviving a broken wind-turbine's signalling lights

    • The original electronics was fried, so I made a new, custom one, which is more fun;
    • The new circuit board uses ATMEGA328 (like the Arduino) and powerful LED-Drivers for the LEDs;
    • There are quite a few modes/effects available;
    • Controlled through a custom protocol over a Bluetooth connection with an Android phone;
    • Android App available.

    View the source code and schematics on GitHub or view it at action on youtube:

    view at github  

    youtube video  

    Tags:  Hardware, Android, Java, C++, Open Source

    Last modified: 25.05.2019


    SOA implementation

    Data and workflow integration concept for a company*

    From location-oriented to a process-oriented data flow

    • Analyzing and optimizing business processes inside a company;
    • Using process-driven approach to hanndle the company's distributed data;
    • Centralizing common workflows and data to avoid duplication and fight waste of ressources.

    *not a real world company

    View the concept at GitHub (in german):

    view at github  

    Tags:  Process Optimization

    Last modified: 15.08.2020


    - Documents -

    Computer science:
    • Bachelor degree in "Digital Engineering and Applied Computer Science" (06.2022)
    • Front End Development from FreeCodeCamp. (10.2017)
    • CS50 - Introduction to Computer Science from Harvard through edX. (05.2017)
    • Machine Learning - Stanford University on Coursera. (06.2017)
    German language:
    • C1 in German from Göthe Institut Göttingen. (03.2017)
    Wind Turbines:
    • Service-Technician Wind-Turbines On-/Offshore BFW Bremerhaven. (02.2015)

    - Contact -