DIY

Knowing parameters of small-signal control-to-output transfer functions makes it easier for engineers to design compensation networks of DC/DC converters. The equations for SEPIC can be found in different works and Application Notes, but there are differences. A work has been done to solve this problem.

Simplified design equations for SEPIC with Current Mode control (CM) in Continuous Conduction Mode (CCM) suitable for practical design of compensation networks are shown.

In this video, we will look at how to connect brushless motor controllers to a Linux computer. Specifically, we will use a computer running Debian. The same steps would work for Ubuntu Linux and other Linux distributions derived from Debian.

I've got a small sensorless brushless motor, and a bigger brushless motor with a built-in absolute encoder. Lets look at how to control those from my Debian Linux computer. Servosila brushless motor controllers come in several form factors with either a circular or a rectangular shape. The controllers come with a set of connectors for motors and encoders as well as for USB or CANbus networks.

The controllers can be powered by a power supply unit or by a battery. To spice up my setup, I am going to use a battery to power the controllers and thus their motors. The controllers need 7 to 60 volts DC of voltage input. If I connect the battery, the controllers get powered up. The small LED lights tells us that the controllers are happy with the power supply.

We need to connect the brushless motor controllers to the Linux computer. There are two ways to do that - via CANbus or via USB. Lets look at the USB option first. A regular USB cable is used. Only one of the controllers needs to be connected to a computer or a PLC.

Next, we need to build an internal CANbus network between the controllers. We are going to use a CANbus cross-cable to interconnect the controllers. Each controller comes with two identical CANbus ports that help chain multiple controllers together in a network. If one of the interconnected brushless motor controllers is connected to a computer via USB, then that particular controller becomes a USB-to-CANbus gateway for the rest of the network. Up to 16 controllers can be connected this way via a single USB cable to the same control computer or a PLC. The limit is due to finite throughput of the USB interface.

As already described in the previous article, in the process of reworking the DSO138 oscilloscope toy, the idea arose in the DSO303 firmware at some point to try to double the maximum sampling frequency to achieve scanning times of 500 and 200 nanoseconds per cell. In fact, for the STM32F303, the theoretically maximum achievable sampling rate from the point of view of the ADC input, and this is determined by the minimum opening time of the ADC sampling unit, which in our case is 1.5 clock cycles x (1/72 MHz) = 20.8 nanoseconds, is 48 MSPS (millions of counts per second). However, with the parallel operation of 4 ADCs at 6 MHz, it is possible to achieve only 24 MSPS due to the limited speed of the ADC.

Let's imagine that we are considering correctly-periodic signal, which is also constant, i.e. it does not experience fluctuations in frequency and amplitude over time. Is it possible to somehow digitize it not in one, but in several passes, thereby increasing the effective sampling frequency? 

On Ali, an interesting toy – an oscilloscope called DSO138 is sold for a very inexpensive price. It has already gained quite a lot of popularity among electronics lovers, but the parameters of this device, alas, allow it to be more or less fully used only for debugging very low-frequency circuits. Actually, it is not positioned as a tool, but rather as a DIY-kit for novice electronics engineers.

This "toy" oscilloscope is assembled on the STM32F103 microcontroller, and with a fairly competent circuit design of the digital part, the presence of a fairly decent 320X240-dot color display, and not the most rotten analog path, everything, alas, is ruined by very weak ADCs on board the 32F103. The claimed band of 200 kHz can be recognized as such only with a very large stretch. Yes, it will show the presence or absence of a signal with such a frequency, but it will not be possible to really look at something beyond this.

At the same time, the 103-series has a slightly more powerful brother - the STM32F303, it is almost completely compatible with the legs, but it is significantly better in terms of the parameters we are interested in, there are 4 ADCs on board with a conversion frequency of 5 MHz (6 MHz with a 10-bit resolution). In this scenario, if you use all 4 ADCs in parallel with a 10-bit resolution, you can get a effective resolution of up to an honest 24 MSPS (millions of samples per second). The microcontroller is also inexpensive; you can easily find it on the same Ali for very reasonable money again. It is clear that the idea to change the microcontroller arose almost immediately after I tried this DSO138.

At the same time, if upgraded the toy can turn out to be a completely full-fledged tool that even professionals, not just novice amateurs, could already use. With these thoughts in mind, I decided to try to do something with a Chinese toy in my free time.

This project is aimed at creating an experimental device for emulating RFID labels of three widely available components. I simplified the explanation of the process so that it could be easily replicated. I also developed some helpful ideas along the way, including writing a special program for converting a serial number into the transmitted data, which will definitely prove useful.

Hackathons could be very intimidating and stressful. The key to getting better is doing simple projects. In this article, we will look at an example of a web app that can be used for sharpening your skills when you prepare for a hackathon. We will use a powerful Google API based on Machine Learning and apply the following technologies: ASP.NET, HTML, Docker, Heroku, and Git.

The idea to build a 4th order low-pass filter looks simple: add one more feedback loop. But there are pitfalls, as always.

Gyrators are impedance converters usually used to simulate inductance in circuits. Though they are rarely used in discrete electronics, they are interesting circuits looking like pole dancers in pictures. There are studies on gyrators, but still something is missing, so it is interesting to do another one.

Common approach to build a 3rd order low-pass filter is to use two circuit stages and two Op Amps. Making a good One Op Amp design is not always easy, but it is possible.

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Ancient times are known to everyone not with immortal works from Homer's only, but also with the Pythagorean multiplication table, Euclidean geometry and the Archimedes screw and the Pi, which we learned to use only relatively recently. In antiquity the art was not only to be able to write poetry and prose, but to design catapults or battering tools also, now there are rigid frameworks, when the discovering the new another beautiful formula is a formal words play only.
Mathematics rules the modern world completely, cynically intertwining with the world of art, intruding with calculations in all spheres of our recreation and everyday life, when the colors of masterpieces turning into poisonous colours.

In 2013 Canonical tried to crowdfund Ubuntu Edge smartphone. Its main feature could be the ability to use the smartphone as a full-fledged PС. Unfortunatly, the crowdfunding campaign did not accumulate enough money, so a dream of having a universal device remained to be the dream.

I've been searching for universality, too, on the software side, not the hardware one. Today I can confidently say I found the necessary combination: Git and JavaScript.

As you know, I have already described the benefits of browser applications (nCKOB static site generator) and the benefits of using Git instead of yet another back-end with API (GitBudget to track personal spendings). Once GitBudget was out, I spent the remaining 2020 to build a system allowing one to create browser applications right inside browsers. GitJS is the name of that system.

When we think about robots, the first thing that comes to mind are robotic vacuum cleaners. The reason is simple: they are the most "solid" demonstration of success of "consumer" robotics. So making one sounds like a good idea... at first.

But isn't it a bit counter productive - to build something that popular, something we can buy in a store at a commodity (small) price? Should we build something similar, but NOT a vacuum cleaner? Something like... a floor washer, perhaps? Yes, a robotic floor washer.

In this tutorial I am going to build a fully working prototype of a robotic floor washer. By "fully working" I mean that it is going to wash floor, instead of moving dirt around like most robotic "moppers" do. While by "prototype" I mean it is going to be the first step towards production-ready unit, but not a production-ready unit yet. Let me explain.

First of all, it is not going to be THAT solid. You can grab a robotic vacuum cleaner that you got from the store by any part, including wheels and bumper and lift it. It will not fall apart. Ours probably will. The reason is, to make a device "mechanically solid" is a separate task, and if we focus on it, then "robotic" tasks will become more difficult to achieve. So we are going to do what engineers usually do: first they build C3PO without the outside body, wires everywhere and so on. And only then they put a gold-covered outfit on it.

The easiest way to build a driver with specified output impedance is to use an amplifier with high load compatibility and add a resistor to its output. The penalty is a voltage drop across this resistor, so there is power loss and we need a higher supply voltage. If our driver is able to deliver the same voltage and current to the same load, but the extra resistor will have a lower value, our device will be able to deliver the same output power at a lower supply voltage. Less power losses, less heat, and longer working time when a battery is used.
There is an idea how to solve this problem: active termination. We can synthesize the output impedance!

Now when we know what we want, go to design our drivers!

If you look through datasheets you will find a strange circuit used in front of some ADCs. It looks like a low-pass filter, but you will not find this topology in books.

Let’s try to figure out what it is, how it works and how to design it.

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?

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.

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.

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…

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.

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.