# Ajantha College and School Students Science Projects materials

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## Archive for the ‘Basic Electronics’ ’ Category

#### Resistor Color Code Chart – Understanding Resistance Color Coding

“Color coding” is used in electronics to identify between different components. In the case of resistors, color coding is used to identify a specific resistance value, for example a 100 ohms resistor or a 1 kilo ohms resistor with 5% tolerance. Electronic components like resistors are very small in size and its difficult to print its value directly on to the component surface. Hence a standard was formed in 1920 by then Radio Manufacturers Association (now part of EIA – Electronic Industries Alliance) to identify values and ratings of electronic components by printing color codes on them. Color coding technique…

#### Pulse Width Modulation – What is it?

The good definition of Pulse Width Modulation (PWM) is in the name itself. It means modulating/varying the width of the pulse (Not the frequency). To best understand what PWM is, let us first see some basic terminologies. Microcontrollers are intelligent digital components which live on binary signals. Best representation of a binary signal is a square wave. The following diagram explains the basic terminologies associated with a square wave signal. As the shown in the above diagram, the important thing to note in a PWM signal is that the time-period and hence the frequency is always fixed. Only the ON…

#### PN Junction Diode and its characteristics

In chapter 1 – Understanding the PN junction , we have seen how a PN junction is formed from a p-type and n-type semiconductor. We have also learned about diffusion current, depletion region, drift current and barrier potential. If you find these terms foreign, just read the chapter about “understanding the pn junction” once more. Lets just make some questions. What is the use of a PN junction? Why have scientists created a pn junction device? What kind of problem it solves ? Learning anything is really fun when we question it. So these are our questions. Why there exists…

#### Understanding the PN Junction

Whenever some one decides to learn electronics, the first question he asks may be – “Where shall I begin?“. I will say, one should begin at a junction the “pn junction“. We know semiconductor devices like transistors and diodes are the basic building units of any equipment that involves electronics, say tablet computers to the sophisticated MRI machines! How these basic units like transistors and diodes are formed ? or how are they made ? The answer lies in understanding “PN Junction”. A PN junction is the basic building block of many semiconductor devices like diodes and transistors. Note:- I…

#### IC Voltage Regulators

A voltage regulator is one of the most widely used electronic circuitry in any device. A regulated voltage (without fluctuations & noise levels) is very important for the smooth functioning of many digital electronic devices. A common case is with micro controllers, where a smooth regulated input voltage must be supplied for the micro controller to function smoothly. Voltage regulators are of different types. In this article, our interest is only with IC based voltage regulator. An example of IC based voltage regulator available in market is the popular 7805 IC which regulates the output voltage at 5 volts. Now…

#### PN junction breakdown characteristics

In this article, we are going to learn a little deep about break down characteristics of PN Junction Diode and how “reverse break down” characteristics is put into practical applications. Before getting into the details, lets have a walk through our previous articles. 1. Understanding the PN Junction – is a great article to begin your learning curve about pn junction. In this article, we have clearly explained what is a pn junction and how is it formed. 2. PN Junction Characteristics- is another great article you must read to understand behavior of a PN junction under different conditions; say…