• Compensation for Error Caused by Limited Gain-Bandwidth of Operational Amplifiers in Low-pass Filters

    • Tutorial
    Amateur vs Pro

    An operational amplifier has the internal compensation circuit for stability which limits its working bandwidth. Frequency response of the compensated Op Amp has slope of −6 dB/octave or −20 dB/decade. Unity gain frequency defines the bandwidth where the Op Amp is able to amplify a signal. If we multiply the gain and frequency at any point, the result is the same, allowing us to use this parameter to select the appropriate Op Amp. It is called Gain-Bandwidth Product, GBW or GBP. The limited open-loop gain introduces a closed-loop gain and phase error.

    But we want to optimize our circuits, right?
    Read more →
  • How to verify Switching-Mode Power Supply circuits

    It is always good practice to verify a circuit before using.

    Switching-Mode Power Supplies are the most used circuits nowadays. But there are some difficulties with verifying their circuits: vendors do not publish models for all controllers; a model can be locked to be used with some tool; there can be errors in a model; average models want correct parameters and you need some practice of using them; transient models take a lot of time to get small-signal response and also can have errors.

    Let’s try to verify one circuit using my favorite electronics design tool “Circuit Calculator”.
    Read more →
  • How to save energy with BARY: Smart Home

    • Translation


    Well, every modern person has at least once wondered: for how much longer can you pay such huge utility bills?! I am no exception. Electricity, gas, heating, water, rent, elevator, removal of solid waste, etc. etc.

    One of the reasons (far from the last) of creating the BARY application was the ability to collect statistics, analyze and reduce energy consumption. Europe has long passed into the regime of total economy; I think this fate will not bypass us. Therefore, to prepare for this in advance definitely will not be superfluous.

    I now propose that we examine how we managed to optimize the cost of electricity along with BARY: Smart Home.
    Read more →
  • How to make your home ‘smart’ without going crazy

    • Translation
    image

    Smart furniture, which keeps your house in order, is a must for almost any futuristic set. In fact, an auto-regulating climate, automatic lights and voice control over household devices — all this can be done and configured now. But it will take a little experience, basic knowledge of technology and sometimes programming, as well as a whole sea of ​​fantasy. In my case, I did in the way that just fantasy will be enough, but first things first…
    Read more →
  • Как с помощью HUAWEI ML Kit самостоятельно создать апплет для фото на документы

      Общая информация


      В предыдущей статье мы рассказали о том, как создать камеру для улыбок с помощью HUAWEI ML Kit. В этот раз я собираюсь представить вам новую функцию HUAWEI ML Kit.

      Вас когда-нибудь просили на учебе или работе принести фотографию определенного размера с цветным фоном для документов? В большинстве случаев у человека не окажется под рукой подходящей фотографии. Однажды в институте нам решили оформить персональные пропуска, но фотостудия оказалась закрыта. Тогда я сфотографировался на телефон, использовав простыню в качестве фона. И получил выговор от преподавателя. Но с помощью инструмента HUAWEI ML Kit вы сможете интегрировать SDK для сегментации изображений в ваше приложение и разработать апплет, чтобы создавать фото на документы самостоятельно и решить проблему отсутствия нужных фотографий.

      Самое главное, что этот SDK абсолютно бесплатный и работает на всех телефонах на базе Android.

      Разработка апплета для фото на документы самостоятельно


      1. Подготовка


      1.1 Добавьте репозиторий Maven Huawei в файл на уровне проекта build.gradle


      Откройте файл build.gradle в корневом каталоге вашего проекта Android Studio.

      image

      Read more →
    • Why I keep track of spendings in a personal app made with Git+JS

      • Translation

      Hi, folks, let me share my experience of creating an application to keep track of my spendings. Specifically, let me do it by answering the following questions:


      1. Why keep track of spendings in an application?
      2. Why did I create the application as a personal project?
      3. Why does the project use Git+JS?

      1. Why keep track of spendings in an application?


      I, like many people out there, wanted to become rich and successful. To become rich, one is often advised to run a personal budget, that's what I started to do several years ago. I'd like to point out that running my personal budget hasn't made me rich and successful, and I increased income simply by moving to Moscow.

      Read more →
    • The snail terrarium concept

      • Translation
      Hello everybody! Today I want to share with you the concept of a rather unusual device, which, like the alarm remote for the "ZAZ Zaporozhets", was developed exclusively for creative purposes, without the further implementation.



      It all started with the fact that two of the three grape snails escaped from our director's terrarium, and the third one died suddenly without lasting even three days. Obviously, the blame for this situation was putted not on the inability to keep the mollusk and irresponsibility, but on the “terrible terrarium”.
      Read more →
    • AdBlock has stolen the banner, but banners are not teeth — they will be back

      More
      Ads
    • Using Data Science for house hunting in Montreal

        Introduction


        I happen to live in Montreal, in my condo on the edge of McGill Ghetto. Close to Saint Laurent Boulevard or the Maine as locals call it, with all it's attractions — bars, restaurants, night clubs, drunken students. And once upon a time, on a particular lively night, listening to the sounds of McGill frosh students drunkenly heading home after hard night of studying. I thought, that it might be a good idea to move into my own house, a little bit further away from the action.


        Image

        Read more →
      • Teaching folks to program 2019, a.k.a. in the search of an ideal program: Sequence

        • Translation

        MUROM


        Hi, my name is Michael Kapelko. I'm a professional software developer. I'm fond of developing games and teaching folks to program.


        Preface


        Autumn 2019 was the third time I participated as one of the teachers in the course to teach 10-15-year-old folks to program. The course took place from mid. September to mid. December. Each Saturday, we were studying from 10 AM to 12 PM. More details about the structure of each class and the game itself can be found in the 2018 article.


        I have the following goals for conducting such courses:


        • create a convenient tool to allow the creation of simple games, the tool interested folks of 10 years old or older can master;
        • create a program to teach programming, the program interested folks of 10 years old or older can use themselves to create simple games.
        Read more →
      • Hypercube. How we gave developers test devices without losing any

          You can’t properly test and debug mobile apps without test devices, which there should be plenty of considering how the same code may behave differently on different models. So how do we keep track of these devices? How do we quickly provide developers and testers with the smartphones they need, configured the way they need, and without much red tape?

          I’m Alexey Lavrenuke. Over the years, I’ve worn many hats: one of the authors behind Yandex.Tank, a speaker on load testing, and the guy who calculated energy consumption by mobile phones. Now I’m a Yandex.Rover developer on the self-driving car team.

          After the phones and before Yandex.Rover, there was Hypercube.

          A few years ago, the head of mobile development popped in to the load testing department and mentioned a problem they were having with test devices: phones had a tendency to inexplicably migrate from one desk to another. Picking the right device and then finding it had become a challenge. We already experienced working with mobile devices from building a digital ammeter to calculate energy consumption, so we decided to help our coworkers out and quickly rig up a handy contraption. We figured the whole thing wouldn’t take more than three months. Oh how wrong we were. Let me tell you what we were really in for.


          ''Dallas cube''
          Read more →
        • Tesla Cybertruck copy was spotted in Moscow. This is a customized… Russian LADA Samara

            image

            Hi Habr! Just noticed that this funny article exists only in Russian, so I’ve decided to translate it to English with some light modifications. Please enjoy!

            Few days ago Tesla Cybertruck replica has been spotted on the roads of Moscow. The design of the electric pickup presented by Elon Musk can't be confused with anything else.
            Read more →
          • Reverse engineering a high-end soldering station



              (This is the translation of the original article performed by baragol)

              We had a bunch of photographs of the main PCB, a YouTube video with drain-voltage waveforms of MOSFETs, a forum post with a breakdown of the capacitance values of LC circuit capacitors and also a number of unboxing videos showing the heating-up of the soldering tip. The only thing that really worried me was the video with the measurement of the peak power consumption during the heating-up. There is nothing in the world more helpless and irresponsible and depraved than burned cartridge newly bought for 60 bucks from Amazon. But let me start from the beginning.
              Read more →
              • +22
              • 10.7k
              • 1
            • Board game for learning the basics of electrical circuits. Why not?


                I made the “electric” designer of… cardboard. Alas, the project still remains at the prototype stage, not developing into an industrial “physical” look and is waiting for its time (and investor).


                But I decided to go further — once we started making cardboard, we’ll bring the situation to its logical conclusion — we’ll make a complete cardboard board game, but with an electric setting and a learning effect. There were a lot of options — starting from a simple “walker” and ending with Ameritrash from a zombie with electron movement and vicious short circuits and swollen capacitors.


                As a result, I decided to dwell on a logical abstract, since the schematics of electrical circuits are very suitable for it. Said and done — as a result of the first iteration, the game “Circuit” was born.

                Read more →
              • We're in UltraHD Morty! How to watch any movie in 4K

                  You’ve probably heard about Yandex’s DeepHD technology they once used to improve the quality of old Soviet cartoons. Unfortunately, it’s not public yet, and we, regular programmers, don’t have the dedication to write our own solution. But I personally really wanted to watch Rick and Morty on my 2880x1880 Retina display. And I was deeply disappointed, as even 1080p video (the highest available for this series) looks really blurry on a Retina display! Don’t get me wrong, 1080p is often good enough, but Retina is designed in such a way that an animation with its pronounced outlines in 1080p looks awfully blurry, like 480p on a FullHD monitor.

                  I decided I want to see Rick and Morty in 4K, even though I can’t write neural networks. And, amazingly, I found a solution. You don’t even need to write any code: all you need is around 100GB of free space and a bit of patience. The result is a sharp 4K image that looks better than any interpolation.


                  Read more →
                • Making a DIY thermal camera based on a Raspberry Pi

                    image

                    Hi everyone!

                    Winter has arrived, and so I had to check the thermal insulation of my out of town residence dacha. And it just turned out a famous Chinese marketplace started to sell cheap thermal camera modules. So I decided to DIY it up and build a rather exotic and useful thing — a heat visor for the home. Why not? Especially since I had a Raspberry Pi lying around anyway… The result is down below.
                    Read more →
                  • Flightradar24 — how does it work?

                      I’m going to hazard a guess and say that everyone whose friends or family have ever flown on a plane, have used Flightradar24 — a free and convenient service for tracking flights in real time.



                      But, if my friends are any indication, very few people know that the service is community-driven and is supported by a group of enthusiasts gathering and sending data. Even fewer people know that anyone can join the project — including you.

                      Let’s see how Flightradar and similar other services works.
                      Read more →
                    • Teaching kids to program

                      • Translation

                      Hi. My name is Michael Kapelko. I've been developing software professionally for more than 10 years. Recent years were dedicated to iOS. I develop games and game development tools in my spare time.


                      Overview


                      Today I want to share my experience of teaching kids to program. I'm going to discuss the following topics:


                      • organization of the learning process
                      • learning plan
                      • memory game
                      • development tools
                      • lessons
                      • results and plans
                      Read more →
                    • $10 million in investments and Wozniak's praise — creating an educational computer for children

                        We interviewed Mark Pavluykovskiy — the creator of the Piper educational computer. We asked him about immigrating from Ukraine to the US, how he almost died in Africa, graduated from Princeton, dropped out of a doctorate in Oxford and created a product that deserved a praise from Satia Nadella and Steve Wozniak.



                        In mid-October the Sistema_VC venture capital fund hosted a conference called Machine Teaching, where creators of various educational startups assembled to talk about technical advancements.

                        The special guest was Mark Pavluykosvkiy, the creator of Piper. His company created an educational computer — a children’s toy that, using wires, circuit boards and Minecraft teaches programming and engineering to children. A couple of years ago Mark completed a successful Kickstarter campaign, got a couple of Silicon Valley investors on board and raised around $11 million dollars in investments. Now he’s a member of Forbes’ “30 under 30” list, while his project is used by Satia Nadella and Steve Wozniak, among others.

                        Mark himself is a former Princeton and Oxford student. He was born in Ukraine, but moved to the US with his mother when he was a child. In various interviews Mark claimed that he doesn’t consider himself a genius, but simply someone who got very lucky. A lot of other people aren’t so lucky, however, and he considers it unfair. Driven by this notion, during his junior year he flew to Africa, where he almost died.
                        Читать дальше →
                      • Receiving shortwave faxes with your PC and an off-the-shelf receiver

                        • Tutorial

                        One of the many botched faxes

                        This is a (rather freely) translated version of this article.

                        When most people hear «fax», they remember those clumsy hybrids of a telephone and a printer straight outta 80s (unless you're in Japan, of course — they're still common there). But did you know that a similar technology is used to provide ship crews with weather data when there's no Internet connection? And Kyodo, a Japanese news agency (they sure like faxes, huh), still broadcasts news like that. And we can decode all this stuff, too — given a receiver, an audio cable and some software.
                        So, how does it look?