FEL: Qucs tutorial for beginners Part1

Qucs- Quite Universal Circuit Simulator - is now as the name suggests, quite universal. Pspice, Tina Pro etc give a very fine experience for circuit designers. But as far as a student is concerned, buying them seems difficult. Even though SPICE and its open source derivatives were free to download, their user interface was diffcult to be handled by a beginner. In such cases, people go for a demo version. But some people need freedom to do anything and Qucs is intended for such people.
Qucs is opensource an run on both Linux and Windows platforms. Most probably, you can find the binary in your OS repo while a readily installable file is available for Windows users.
After successful installation, launch qucs from menu or entering command 'qucs' and hitting enter. A window similar to figure shown will appear with a plane work space. Click components and add std. compnents to workspace by drag and drop. You can change the component parameter by double clicking on the component. A label should be added to the workspace to indicate that which simulation you are doing. For a beginner, it is easy to learn simulation in Qucs after watching this video: Qucs.ogv

Download Qucs video tutorial : Qucs.ogv

Download Qucs sources.

Download Qucs for Windows
Note: You need FreeHDL to be installed along with Qucs in order to simulate digital circuits properly. It will be installed automatically if you install it from repo. If not, you should manually download and install and reinstall Qucs if necessary.

FEL: Introduction to MCU8051IDE

There is a lot of free and propitiatory IDEs for micro controllers. Here I like to write about MCU 8051 IDE - An open source project packaged under FEL (Fedora Electronic Lab). Intel 8051 is a standard micro controller and that's why it is essential in engineering syllabus even though some good stuffs are there in newer micro controllers from Microchip, Atmel etc. Simulating 8051 is pretty easy if you own a good 8051 IDE. There is a lot of IDEs available for 8051 simulation and emulation. But it is not a good idea to spent your valuable money for that, if such good free and open source IDEs are available. I am just coming to my point. It is about MCU 8051 IDE. It is packaged with fedora electronic lab. If you intend to stick with other OS, you need to compile the source code. Currently it supports more than 79 MCUs. Know more and how much powerful it is. I have uploaded a screencast of MCU 8051 IDE and I think it is enough to start with for a beginner who knows assembly level programming in 8051. Of course, one can write and simulate the program in C also.
Download video tutorial mcu8051.ogv.

You can view the screencast with VLC media player or any other ogv supported media player.

mcu8051IDE for Windows

Inside the Mosquito killer

Nowadays, people widely uses mosquito killer bats because of their easy usage. The product is imported from China for very cheap price. There's some electronics inside it. If you understand the working principle of that circuit and if you are an owner of soldering iron, you can easily troubleshoot the problems and can use the product for a long time.
The power source of old products was dry cells, while now it is rechargable battery of 2.4V. There is bridge rectifier and a capacitor is used to get enough power to charge the battery. Transistor become ON, when switch is closed and the sudden change in current in the primary coil in the transformer forms a higher voltage. The voltage is coupled to the secondary coil. transformer winding is so that peak voltage will be about 2000V. The diode network only pass a fraction of the output voltage to the metal net.

Slider game using Qt

It is better to do simple things first in Qt before making hands dirty with complex programs. Now I just prepared a slider game using Qt.Hope all of you know how to play slider game. My code is simple and having a slider panel of 3x3 matrix. I know the code is not much pretty. But I just put my source code to download. It may be helpful for beginners. Of course, you can modify the code to satisfy your needs.
Enjoy!

Download slider.zip
Note: You need to recompile the code before using. I successfully compiled the code in Linux. Of course, you can compile it in other platforms without modification of code.

Welcome note on Puppy Linux boot up screen

Is it fun to display a welcome note with your name while booting up Puppy linux? If you think so, you can continue reading. Here I am telling how to set up your Puppy Linux to display "Welcome, {your name}" at boot up. Probably you can do this in other Linux based OS with slight or no modifications. But nowadays bulky operating system intentionally hide the boot up screen with a splash image.
First of all, navigate to /etc/rc.d
Then open 'rc.sysinit' . You should have root privileges in order to edit this file. Read carefully the 'Read me' file before going to do anything. If you are not going to take a risk, back up the file into any other externally accessible directory.
After you open the file in your favourite text editor, just go through the file, you will notice that, this script is automatically executed at every boot up. Go to the end of the file and append the following script.

##########CUSTOM SCRIPT##############
echo -n "

" >/dev/console
/bin/echo -e "\\033[10G\\033[1;34mWelcome, {Your name}\\033[0;39m" >/dev/console
echo -n "

" >/dev/console
sleep 2
###################################

Edit the script with your name instead of '{Your name}'. The script is nothing but an echo statement to the console. It is possible to change the display properties by changing the parameters along with the text. First test it in terminal and then write script is recommended. Now save the file and reboot.
Done.
If you avoid 'sleep 2' statement, you may not see the text at boot up. One best way is remove the line 'sleep 2' and set a login password for Puppy as I did. Then Puppy gives a cool welcome to you and then ask password.