Viki Lab

In this tutorial video we discuss about declaration and initialization with examples to give you an idea how to simplify the length of code to achieve the same result by using only a few lines of code. Each example in the video takes you to a more simplified version of the code. Many programmers write their code first as the wish and in the later stages they may look at ways to reduce the length of the code.As always a short code runs faster than a lengthy code. Try to practice the examples in the video and use few lines of code where ever possible. Download the PDF @ https://goo.gl/NieqYW All Codes Can be downloaded @ https://goo.gl/WBiiKI Download The Dev-C++ IDE @ https://sourceforge.net/projects/orwelldevcpp/

This video shows how to identify the pins 2n3055 transistor by two ways: 1.By using the datasheet of the transistor. 2.By using the multimeter & the datasheet. Although the datasheet provides the correct information to identify the pins of this transistor majority of the people find it very difficult to extract this information directly from the data sheet as identifying the pins from the transistor depends upon the physical dimensions of the transistor. Although the transistor layout looks symmetrical it is not ,so measuring or judging by the eye is difficult as the difference is only a few millimeters. In this video with the aid of a multimeter we determine the pins of this transistor very precisely. The datasheet clearly states  that the metal casing  of the transistor is the collector so the problem is actually determining the base and the emitter of the transistor. For the process we start by putting the multimeter to the diode mode and then connecting the ...

Comments in C++ Programming Comments are used mainly to describe the code. Comments are ignored by the compiler. There are two types of comments: Single line comments. Multi-line comments. Single line comments start with two forward slashes // Comments are just to describe the code,they are never executed. Multi-line comments: This type of comments are used to comment out multiple lines. This type is better for giving a detail description of how the code functions. Multi line comments start with /* and end with */ In between the content is added. Multi line comments span multiple lines. You can even nest comments one type of comment inside another . Adding comments in the code makes no difference to The results of the code is as the comments have no influence on the code. Adding comments is a good practice as it facilitates a clear understanding of the code for you and others as well. Example: /* Hello user this Is an example of multi line commenting*/ ...

How To Make a 0-12V Variable Power Supply In Sinhala | Part 02 Expanding the setup to a 0-12V variable power supply. We have already completed the 12V fixed powersupply tutorial vide so if you havent watched it first watch it and continue. By now we have completed the project upto a 12V fixed power supply as our next step we are to make the power supply variable. Additional Components Required: D400 x1 2N3055 x1 100kO variable resistor 1kO  Determining the pins of the d400 transistor is very straight forward but it can be tricky in the case of 2n3055. Refer the pdf for the pin configuration of the D400 transistor: 2N3055 : According to the data sheet the metal casing is the collector of the transistor. The problem is identifying the base and the emitter of the transistor. Steps: Put the multimeter to the diode mode. Connect the probes of the multimeter to the two leads of the transistor. If there is a reading on the multimeter then the positive probe is th...

In this tutorial you will learn everything about using and printing on new lines. There are many methods to use new lines, the most fundermental method is to use  the endl operator at the end of the cout statement. The endl operator make sure that the next cout statement will be printedc on a new line. The endl can be replaced by the use of the new line character \n. the \ is an escape character.Sometimes is essential that we need to escape many lines before the next text is printed on to the screeen  for this in C++ the new line character can be used as required.  \n\n will escape two lines before the next text get printed on the screen. where the use of \n\n\n\n\n would print 5 blank lines before the next text is printed. C++ provides us futher options to simplify the code for printing text on to the screen. In C++ it is possible to print new lines as required inside a single cout ,  this is done by inserting the newline escape character where requ...

Variable Resistor එකක අගය සරලව ගණනය කර ගන්නා ආකාරය සිංහල බසින්!   These are a special type of resistors that provide us the ability to change their resistance as required by the user. Basically there are two versions available at traditional electronic shops as; -Volume control (Big Size) -Preset (Small Size) Volume control type can be very easy to manipulate due to the large size. These resistors cannot handle much power (~0.25W). These devices usually comes with three terminals and could be used in two major ways: 1. As a variable resistor. 2. As a potential divider. The smaller version (preset) are to be tuned to the required resistance with the help of a screw driver but the volume control type can be easily tuned as required with the help of our hand. Variable resistors have a variety of applications such as controlling your radio's volume, changing the speed of your fan... To use the device as a variable resistor we only use two pins out the three simple ...

අදුරට සංවේදී පරිපටයක් සකස් කර ගන්නා ආකාරය සරල සිංහලෙන්. Dark sensitive circuits have a range of applications such as turning on lights when the light level falls below a certain threshold.In our circuit this threshold is changed by using a variable resistor which can be turned to fine tune the circuit. The circuit consists of the following components: C828 transistor x1 7805 voltage regulator x1 1 kilo ohms resistor x1 LDR x1 LED x1 100 kilo ohms variable resistor.  The base current of the transistor is controlled by the potentiometer.In very low light conditions the ldr will have a very high resistance and in high light conditions the ldr will have a low resistance.In the dark condition less current will flow through the ldr so more current passes through the base of the transistor causing a high current flow through the led via the collector pin of the transistor causing the led to light up but in high light condtions the ldr will have a low resistance there for most...

සරල Water Level Sensor එකක් D400 transistor එකක් භාවිතා කර සාදා ගැනීම!  Water level sensors can be used for many interesting projects. Examples : -To switch a water pump on and off to fill the water tank automatically. -To gather rainfall data. Part List: D400 transistor x 1 1 kO resistor x 1 150-330O resistor x 1 LED x 1 Ic 7805 Voltage regulator  Transistors consists of three pins as : *Emitter *Collector *Base 7805 regulation is used to add an extra layer of protection for the circuit. The user can directly omit the 7805 regulation part if the user can apply suitable voltage. The first circuit is a case where the presence of water will cause the led to light up  1 kilo ohms resistor is placed in series with the base pin to prevent too large base current. The 330 ohms resistor places in series with the led is to prevent too large current from flowing through the  led, the probes must be selected according to the application sometimes you may need corrosion resistan...

5V Regulator එකක් භාවිතා කර Phone Charger එකක් නිර්මාණය කරමු! The 78xx is a series of fixed-voltage integrated-circuit voltage  regulators designed for a wide range of applications. The Ic can handle upto about 1.5A of current. Working temperature 0 – 125 º Celsius Examples : -7805 (5v regulator Ic)  -7812 (12v regulator Ic) Properties : -Thermal shutdown features. -Overload current limiting features. -High power dissipation capability. -Bias current (~1–10mA). Part List: 7805 IC 0.33 μF 0.1 μF When the circuit is set you can successfully obtain 5v output from a varying dc voltage source (7-25V). The capacitors helps to stabilize and filter noise of the input.  Applications: Powering a micro controller Making a mobile phone charger 7805 regulators are cheap and efficient. Visit our web site : www.vikilab.com References : LM7805 Data Sheet @  https://www.sparkfun.com/datasheets/C...

12V DC Power Supply එකක් Step Down Transformer එක භාවිතයෙන් ලබා ගැනීම සරල සිංහල බසින්! We cannot use 230V directly from the mains supply for most of our day to day projects so a dc power source is really essential as we cannot relay of batteries due to the daily cost. The problem can be solved by using building our own power supply. Here we constructs a 12V dc power supply. Part List: -12V X 2 step down center tapped 300mA transformer. -230v plug socket. -Flexible wire (1m). -Heat sleeve (5cm).  -Insulation tape. -2200 µF capacitor.  -330 O resistor -Led.  -IN4001 or IN4007 diodes X 2. Working principle: * The 12Vx2 center tapped transformer convert the 230V AC to 12 V AC * The pair of diodes then rectifies the 12V AC wave form to 12V DC This output is continuously varying between 0-12V which is not suitable for most of our work what we need is a stable dc power supply of 12 V *The capacitor charges and discharges according when required to give us a stable 12V DC output ...

Step down transfomer එකක් යොදාගෙන 12V DC ජව සැපයුමක් සාදා ගැනීම. Transformers are of two types : -Step up -Step down In this we are dealing with step down transformers,basically step down transformers convert a high voltage to a low voltage Here we are using a 12V X 2 center tapped transformer (300mA) the input voltage of the transformer is 230V the input wires are denoted by red color in this case the output side wires are easy to be recognized as there are 3 wires (2 black wires & 1 yellow wire) The voltage between the yellow wire and any black wire is 12V & the voltage betweeen the two black wires is 24V. These transformers can be used for many applications such as construction of power supplies in the upcomming videos we are going to use this transformer to construct a 0 - 12V variable power supply. The input is connect to the mains via a plug top and 2 wires  the soldering of the wires are insulated by using heat sleeve and insulation tape. PDF Download -  https:/...

LED Brightness Control With PWM Function In Arduino LED බල්බයක Brightness විචලනය පාලනය කිරීම සහ PWM Function එක භාවිතා කර RGB LED එකක පාට හැසිරවීම සරල සිංහල බසින්. Brightness of an led cannot be directly controlled as the Arduino works with 5v and 0v (digital) for this we use the analogWrite function to generate pwm pulse wich will inturn help us to change the brightness Part list : 150-330 ? resistor x 1 Led x 1 Arduino board x 1 Jumper wires Bread board x 1 RGB led x 1 Steps: Connect the Arduino board to the computer via the USB cable. Open up Arduino IDE. Select the correct COM Port. Select the correct Board . Type the code and Upload. Group Link : https://www.facebook.com/groups/vikil... Page Link : https://www.facebook.com/vikilabs17/ Code and Tutorial PDF Zip - https://drive.google.com/open?id=0B-x...

Knight Rider Circuit with Arduino In Sinhala   පහසුවෙන් Knight rider circuit එකක් සාදා ගන්නා අයුරු සරල සිංහල බසින්! The digital pins of the Arduino can be used to power the led’s of this circuit To limit the current flowing through the LED’s we use a resistor (150 -330 ?) connected series with the ground pin of the Arduino board. Part list : 150-330 ? resistor x 1 Leds x 10 Arduino board x 1 Jumper wires Bread board x 1 Steps: Connect the Arduino board to the computer via the USB cable. Open up Arduino IDE. Select the correct COM Port. Select the correct Board . Type the code and Upload. Have fun by changing the delays. Try – delay(100); Group Link : https://www.facebook.com/groups/vikil... Page Link : https://www.facebook.com/vikilabs17/ Code and Tutorial PDF Zip - https://drive.google.com/open?id=0B-x...  

Fixed Resistors.        Fixed resistors පිළිබඳ සරල සිංහලෙන් දැනගමු! • Resistance is the opposition for the current flow. • Resistance is measured in ohms ( Ω ) • Fixed resistors have a fix value of resistance. • Circuit Symbols:    • Physical appearance of the resistor :  • Resistance can be measured directly  multimeter   . Steps : ´ Set the multimeter to the resistance range ´ Connect the resistor to the multimeter leads ´ Take the reading on the display ´ Resistance of the resistor can also be calculated using the colour bands printed on the surface of the resistor: ´ Steps  ´ Observe the 1 st 3 color bands of the resistor (starting from the opposite end to silver or gold color band) ´ Each colour represents a number. ´ Combining the numbers we can calculate the resistance value. Example 1 : Example 2 : ´ The 4 th color band gives the tolerance ...

How To Blink a LED With Arduino In Sinhala  Arduino මුලධර්ම භාවිතයෙන් පහසුවෙන් LED බල්බයක් නිවී නිවී දැල්වෙන අවස්ථාව උදා වීම සහ එමගින් ඉතා සාර්ථක ආලෝක රටාවක් සැකසා ගැනීම වනතෙක් සියළු පියවර අන්තර්ගතව ඔබ වෙත  ඉදිරිපත් කරන  වීඩියෝවයි මේ! In this video we need;  Output pins of the Ardunio board has the ability to give around 20 mA per I/O pin. This 20 mA is more than enough to switch on an LED. Rather than using the full current we are to limit the current by using a resistor in series. A good resistor value is 330 ohms. (use can use any resistor between 150 – 330 ohms) Steps : Connect the Arduino board to the computer via the USB cable. Open up Arduino IDE. Select the correct COM Port. Select the correct Board . Type the code and Upload. Code and Tutorial PDF Zip - https://drive.google.com/open?id=0B-xkwb9ASKxXWmhSOTdFTjlGTDQ

How To Power Up a LED From Arduino's 5V Output Explained In Sinhala | 01 Arduino board has given us opportunity to obtain a power output of 5V once its connected to the computer. Its is possible to draw up to about 700 mA from the board safely via the USB Connection. This output can be used for any project that does not consume too much current with or without  the board itself running a code at all.The advantage of this is that you don't need an external power supply to build your simple projects. Arduino board එකේ 5V power output මගින් සරලව LED බල්බයක් දල්වා ගන්නා අයුරු දන්න සිංහලෙන්.    FB Group Link : http://www.facebook.com/groups/vikilabs17 FB Page Link : http://www.facebook.com/vikilabs17/ Presentation : https://drive.google.com/open?id=0B-xkwb9ASKxXSTRUTkhNeFg2TnM