Basic Electronics Mv Rao Pdf Free Download
Roseanne Devon
Getting started with basic electronics is easier than you might think. This Instructable will hopefully demystify the basics of electronics so that anyone with an interest in building circuits can hit the ground running. This is a quick overview into practical electronics and it is not my goal to delve deeply into the science of electrical engineering. If you are interested in learning more about the science of basic electronics, Wikipedia is a good place to start your search.
Electricity can also be defined in terms of resistance and watts. We will talk a little bit about resistance in the next step, but I am not going to be going over Watts in depth. As you delve deeper into electronics you will encounter components with Watt ratings. It is important to never exceed the Wattage rating of a component, but fortunately that Wattage of your DC power supply can easily be calculated by multiplying the voltage and current of your power source.
In order to build circuits, you will need to become familiar with a few basic components. These components may seem simple, but are the bread and butter of most electronics projects. Thus, by learning about these few basic parts, you will be able to go a long way.
There are two basic types of transistors, which are NPN and PNP. These transistors have opposite polarity between collector and emitter. For a very comprehensive intro to transistors check out this page.
Potentiometers have three legs as to create a voltage divider, which is basically two resistors in series. When two resistors are put in series, the point between them is a voltage that is a value somewhere between the source value and ground.
LED stands for light emitting diode. It is basically a special type of diode that lights up when electricity passes through it. Like all diodes, the LED is polarized and electricity is only intended to pass through in one direction.
At last someone who understands that us over 60s didn't learn anything about electronics at school many thanks for a great introduction and I will be trying out a few things that I have looked at in the past with great mystery MANY MANY THANKS
The goal of this chapter is to provide some basic information about electroniccircuits. We make the assumption that you have no prior knowledge of electronics,electricity, or circuits, and start from the basics. This is an unconventional approach,so it may be interesting, or at least amusing, even if you do have some experience. So,the first question is ``What is an electronic circuit?'' A circuit is a structure thatdirects and controls electric currents, presumably to perform some useful function. Thevery name "circuit" implies that the structure is closed, something like a loop.That is all very well, but this answer immediately raises a new question: "What is anelectric current?" Again, the name "current" indicatesthat it refers to some type of flow, and in this case we mean a flow of electric charge,which is usually just called charge because electric charge is really the only kind thereis. Finally we come to the basic question:
No one knows what charge really is anymore than anyone knows what gravity is.Both are models, constructions, fabrications if you like, to describe and representsomething that can be measured in the real world, specifically a force. Gravity is thename for a force between masses that we can feel and measure. Early workers observed thatbodies in "certain electrical condition" also exerted forces on one another thatthey could measure, and they invented charge to explain their observations. Amazingly,only three simple postulates or assumptions, plus some experimental observations, arenecessary to explain all electrical phenomena. Everything: currents, electronics, radiowaves, and light. Not many things are so simple, so it is worth stating the threepostulates clearly.
First we return to the basic assumption that forces are the result of charges.Specifically, bodies with opposite charges attract, they exert a force on eachother pulling them together. The magnitude of the force is proportional to the product ofthe charge on each mass. This is just like gravity, where we use the term "mass"to represent the quality of bodies that results in the attractive force that pulls themtogether (see Fig. 4.1).
Charge is mobile and can flow freely in certain materials, called conductors. Metalsand a few other elements and compounds are conductors. Materials that charge cannot flowthrough are called insulators. Air, glass, most plastics, and rubber are insulators, forexample. And then there are some materials called semiconductors, that, historically,seemed to be good conductors sometimes but much less so other times. Silicon and germaniumare two such materials. Today, we know that the difference in electrical behavior ofdifferent samples of these materials is due to extremely small amounts of impurities ofdifferent kinds, which could not be measured earlier. This recognition, and the ability toprecisely control the "impurities" has led to the massive semiconductorelectronics industry and the near-magical devices it produces, including those on yourRoboBoard. We will discuss semiconductor devices later; now let us return to conductorsand charges.
Ohm's law describes the relationship between voltage, V , which is trying to forcecharge to flow, resistance, R , which is resisting that flow, and the actual resultingcurrent I . The relationship is simple and very basic: . Thus large voltages and/or low resistances produce large currents. Large resistorslimit current to low values. Almost every circuit is more complicated than just a batteryand a resistor, so which voltage does the formula refer to? It refers to the voltageacross the resistor, the voltage between the two terminal wires. Looked at another way,that voltage is actually produced by the resistor. The resistor is restricting the flow ofcharge, slowing it down, and this creates a traffic jam on one side, forming an excess ofcharge with respect to the other side. Any such charge difference or separation results ina voltage between the two points, as explained above. Ohm's law tells us how to calculatethat voltage if we know the resistor value and the current flow. This voltage drop isanalogous to the drop in water pressure through a small pipe or small nozzle.
Resistors are often connected together in a circuit, so it is necessary to know how todetermine the resistance of a combination of two or more resistors. There are two basicways in which resistors can be connected: in series and in parallel. Asimple series resistance circuit is shown in Figure 4.4.
Like resistors, capacitors can be joined together in two basic ways: parallel andseries. It should be obvious from the physical construction of capacitors that connectingtwo together in parallel results in a bigger capacitance value. A parallel connectionresults in bigger capacitor plate area, which means they can hold more charge for the samevoltage. Thus, the formula for total capacitance in a parallel circuit is:
Inductors are the third and final type of basic circuit component. An inductor is acoil of wire with many windings, often wound around a core made of a magnetic material,like iron. The properties of inductors derive from a different type of force than the onewe invented charge to explain: magnetic force rather than electric force. When currentflows through a coil (or any wire) it produces a magnetic field in the space outside thewire, and the coil acts just like any natural, permanent magnet, attracting iron and othermagnets. If you move a wire through a magnetic field, a current will be generated in thewire and will flow through the associated circuit. It takes energy to move the wirethrough the field, and that mechanical energy is transformed to electrical energy. This ishow an electrical generator works. If the current through a coil is stopped, the magneticfield must also disappear, but it cannot do so immediately. The field represents storedenergy and that energy must go somewhere. The field contracts toward the coil, and theeffect of the field moving through the wire of the coil is the same as moving a wirethrough a stationary field: a current is generated in the coil. This induced current actsto keep the current flowing in the coil; the induced current opposes any change, anincrease or a decrease, in the current through the inductor. Inductors are used incircuits to smooth the flow of current and prevent any rapid changes.
Pure silicon is not a conductor because there are no free electrons; all the electrons aretightly bound to neighboring atoms. To make silicon conducting, producers combine or"dope" pure silicon with very small amounts of other elements like boron orphosphorus. Phosphorus has five outer valence electrons. When three silicon atoms and onephosphorus atom bind together in the basic silicon crystal cell of four atoms, there is anextra electron and a net negative charge. Figure4.11shows the crystal structure of phosphorus doped silicon.
Both p-type and n-type silicon will conduct electricity just like any conductor;however, if a piece of silicon is doped p-type in one section and n-type in an adjacentsection, current will flow in only one direction across the junction between the tworegions. This device is called a diode and is one of the mostbasic semiconductor devices.
When working with electronics, it seems you never have enough hands to hold everything. This is where the helping hand (3rd hand) comes in. Great for holding circuit boards or wire when soldering or tinning.
A heat gun is used to shrink plastic tubing known as heat shrink to help protect exposed wire. Heat shrink has been called the duct tape of electronics and comes in handy in a wide variety of applications.
There are a number of basic concepts that form the foundations of today's electrical, electronics and radio technology. Electrical current, voltage, resistance, capacitance, and inductance are a few of the basic elements of electronics and radio.
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