ELECTRONICS FOR BEGGINERS

Dr. Saurav Chakraborty

An electrical current is the flow of electrons in a wire. Electrons flow in a “closed loop”. Loop is formed by a path if the negative and the positive terminal of a battery is connected.

For example if you connect a small light bulb to the positive and the negative side of a battery, you will get a closed loop where electrons can flow and make the lamp glow.

Basic Understanding of Voltage, Current and Resistance. Current flows, resistance resists, voltage pushes.

And they all affect each other.

To understand how they work in a circuit following steps to be followed. You should also know how these components work and what they do in a circuit.

Resistance is an element which opposes the flow of current

Resistance is a current limiting device when current of any circuits needs to be reduced then this is used.

Now you can made circuit. You can see now how circuit diagram works. Resistors can be made to control the flow of current, to dissipate power. Basic unit is ohms, (Ω)

ELECTRONIC COMPONENTS :

Components can be classified into

1. Passive Components: Components like resistance, capacitance inductance.

2. Active Components: Semiconductor Devices such as

diode, zener diode, and varactor diode etc. Uni-junction transistor, Bipolar Junction Transistor (BJT), FET, silicon, rectifier etc., Light emitting diode, photosensitive transistor etc.are active components.

RESISTANCE

To know value of Resistance, they have different colored rings around their body (see Figure). The first ring represents the first digit of the resistor’s value. The second ring represents the second digit of the resistor’s value. The third ring tells you the power of ten to multiply by. The final and fourth ring represents the tolerance.

Color value:-Black 0, Brown 1, Red 2, Orange 3, yellow 4, Green 5, Blue 6, Violet, Gray 8 and White 9. COLOR VALUE

series circuit

A series circuit is a circuit in which resistors are arranged in a chain, so the current flows in one path. The current is the same through each resistor. The total resistance of the circuit is found by adding up the resistance values of all resistors:

Equivalent resistance of resistors in series: R = R₁ + R₂ + R₃

A series circuit is shown in the diagram above. The current flows through each resistor are same. If the values of the three resistors are:

If battery voltage is 10 V, according to Ohm’s Law, V = I R the total current in the circuit is: I = V / R = 10 / 20 = 0.5 A. The current through each resistor would be 0.5 A.
Parallel circuits

A parallel circuit is a circuit in which the resistors are arranged with their heads connected together, and their tails connected together. The current in a parallel circuit breaks up, with some flowing along each parallel resistance and re-combining when the branches meet again. The voltage across each resistor in parallel is the same.

The total resistance of a set of resistors in parallel is found by adding up the reciprocals of the resistance values, and then taking the reciprocal of the total resistance: equivalent resistance of resistors in parallel: 1 / R = 1 / R₁ + 1 / R₂ + 1 / R₃ +...

Voltage drop V = I.R, I is current,

Power dissipation P = I²R = V²/R

A parallel circuit is shown in the diagram above. In this case the current supplied by the battery splits up, and the amount going through each resistor depends on the resistance. If the values of the three resistors are: With a 10 V battery, by Ohm’s Law, V = I R the total current in the circuit is: I = V / R = 10 / 2 = 5 A.
The individual currents can also be found using I = V / R. The voltage across each resistor is 10 V, so:
I₁ = 10 / 8 = 1.25 A
I₂ = 10 / 8 = 1.25 A
I₃=10 / 4 = 2.5 A
Note that the currents add together total become 5A.

A parallel resistor short-cut

You have three resistors in parallel, with values 6 ohms, 9 ohms, and 18 ohms. The smallest resistance is 6 ohms, so the equivalent resistance must be between 2 ohms and 6 ohms (2 = 6 /3, where 3 is the number of resistors).

Doing the calculation gives 1/6 + 1/12 + 1/18 = 6/18. Making this upside down gives 18/6 = 3 ohms, which is certainly between 2 and 6.

Remember that for resistors in series, the current is the same for each resistor, and for resistors in parallel, the voltage is the same for each one.

Circuits with series and parallel components

More examples of resistance calculations

In the following circuit calculate the total current taken from the 12v supply.

At first glance this may seem a difficult, but if we look a little closer we can see that the two resistors, R₂ and R₃ are connected together in a “SERIES” combination so we can add them together to get an equivalent resistance. Resistance for this combination would therefore be:

R₂ + R₃ = 8Ω + 4 Ω = 12 Ω

So we can replace both resistors R₂ and R₃ above with a single resistor of resistance value 12 Ω

So our circuit now has a single resistor R_A in “PARALLEL” with the resistor R₄. Using our resistors in parallel equation we can reduce this parallel combination to a single equivalent resistor value of R_{(combination)} using the formula for two parallel resistors as follows.

The resultant resistive circuit now looks something like this:

We can see that the two remaining resistances, R₁ and R_(comb) are connected together in a “SERIES” combination and again they can be added together (resistors in series) so that the total circuit resistance between points A and B is given as:

R_( A B ) = R_comb + R₁ = 6 Ω + 6 Ω = 12 Ω.

and a single resistance of 12 Ω become total of the four resistors connected together in the original circuit.

Now by using Ohm´s Law, the value of the circuit current ( I ) is simply calculated as:

So any complicated resistive circuit consisting of several resistors can be reduced to a simple single circuit with only one equivalent resistor by replacing all the resistors connected together in series or in parallel using the steps above.

when a LED is connected to a

Capacitors

These are simple components. It consists of two pieces of

conducting material (such as metal) separated by a non-conducting (insulating) material called a dielectric. The capacitance units is farads, F, pF.

Value of the capacitance is given by Its value and the max specify. V Voltage which

can be safely applied to its

When capacitor is put in parallel the overall capacitance C is

C = C1 + C2 + C3 + ------

and in series—1/C=1/C₁+1/C₂+1/_C3---

The diode as a switch

• Diodes can be used as passive switches – to conduct positive voltages along one path and negative voltages along another

• Example: voltage doubler

10V

V_out+20V

There are two types of main capacitor-Ceramic capacitor and Electrolytic capacitor. There are also other types of capacitors.

(ceramic)

They are often used to make rectified DC supply ripple free. In a radio tuning into the station is done by a capacitor. Capacitor can be considered as a battery with very low capacity. It can be charged and discharged just like a battery.

Electrolytic capacitor

The capacitor is often used to introduce a time-delay in a circuit, for example to blink a light. It’s commonly used for removing noise and makes DC voltage of a circuit stable. Using Capacitors For Filters

You can also combine capacitors and resistors to form filters to remove specific frequencies. In an audio system you can remove the high frequencies. This is called a low-pass filter.

There are 2 types of capacitors ceramic and electrolytic. There are also other types of capacitors.

INDUCTORS:- Like capacitors, inductors also store energy in one part of AC cycle and return it during the next part of the cycle.

Inductance is that property of a device that prevents change in current through the device. Inductors are components designed for use in circuits to resist changes in current and thus serve important control functions. Because inductors tend to reject the flow of rapidly changing currents, they can be used to filter out high frequency signals.

TRANSFORMERS:

The transformers used in electronic circuits may be classified into three classes depending on their application.

Power transformers used for power supply. Audio transformers are used as input and output transformers and isolation transformers.

Pulse transformers used in many types of pulse circuits.

Transformer with magnetic core

It has two windings; 1. primary and 2. secondary

If ac voltage is applied in primary winding, magnetic field is produced which cuts the secondary winding of the transformer and voltage is induced in it? It can be step up transformer and step down transformer.

• This is called a transformer.

• For AC (time-varying) signals, it transforms the voltage applied in primary is transformed in secondary according to its turns ratio.

• A transformer isolates the two sides of the transformer – there is no electrical connection between two windings other than through the magnetic field. This is desirable for safety reasons

If V_Ais the primary input voltage and V_Bis the secondary voltage output and number of turns of primary is N1 and number of turns secondary is N2, voltage ratio of transformer will be

V_A/V_B= N1/N2, V_B= V_AXN2/N1 and I_B= I_AX Ni/N2. I_A and I_B are the primary and secondary current.

DIODE

Now you can try to understand some components. Two types of semiconductor material are there which known as P - type and N – types of semiconductors such as silicon and germanium.

p-type : Impurity Of lower group, it contain excess of holes or deficiency of electrons.

n-type : impurity of higher group, contains excess of electrons or deficiency of holes.

What is a Diode?

Diode is a semiconductor device with two terminals, allowing the flow of current in one direction only and blocks current flowing in the other direction.

•The p-side is called anode and the n-side is called cathode.

•When the anode and cathode of a pn-junction diode are connected to external voltage such that the potential at anode is higher than the potential at cathode, the diode is said to be forward biased.

–In a forward-biased diode current is allowed to flow through the device.

•When potential at anode is smaller than the potential at cathode, the diode is said to be reverse biased. In a reverse-biased diode current is blocked

The diode symbol is like this:

A Diode can be connected as bellow

In the circuit above the diode is connected in the right direction. So, current can flow through it to glow the LED. But if the diode is connected in the opposite direction current will not flow and so LED will not glow

A lot of the devices, we use, need direct current (DC). To get DC from AC we need a rectifier circuit. It rectifies alternating current (AC) power supply in our home to get direct current (DC). It is used as rectifier and converts AC input voltage to a pulsed DC output voltage to DC power supply. Fig below is a half-wave rectifier.

Diode Applications

—Half Wave Rectifier

Diode converts ac input voltage to a pulsed dc output voltage.

Whenever the ac input becomes negative at diode’s anode, the diode blocks current flow. Output voltage become zero.

Diode introduces a 0.6V drop so output peak is 0.6V smaller than the input peak voltage.

The output frequency is same as the input frequency.

Half wave rectifier

Vin Full wave rectifier

Full Wave Rectifier

• A full-wave rectifier does not block negative swings in the input voltage; rather it transforms them into positive swings at the output.

• To understand its working, follow current flow through pairs of diodes in the bridge circuit.

• It is easily seen that one pair (D3-Rout-D2) allows current flow during the positive half cycle of Vin while the other pair (D4-Rout-D1) allows current flow during the negative half cycle of Vin.

Output voltage peak is 1.2V below the input voltage peak.

The output frequency is twice the input frequency.D1 D3 D2

A full-wave rectifier does not block negative swings in the input voltage; rather it transforms them into positive swings at the output. The p-side is called anode and the n-side is called cathode. To gain an understanding of device operation, follow current flow through pairs of diodes in the bridge circuit.

AC to DC Power Supply from AC power Supply

An AC to DC power supply is built using a transformer and a full-wave rectifier. Transformer is used to step down the input voltage. Rectifier converts AC to pulsed DC. A filter capacitor is used to remove pulses. Capacitor must be large enough to store sufficient charge to provide a steady current supply to the load: It is used in mobile charger, amplifier, Radio, TV and in almost all equipment we use and find all around.

How a Diode Works

The diode is created from a PN junction. You get a PN junction by taking negative doped and positive doped semiconductor material and putting it together.

Types of Diodes

There are many types of diodes. The most common are signal diodes, rectifier diodes, zener diodes and Light-Emitting Diodes (LED). Signal and rectifier diodes are almost the same thing except that rectifier diodes are built to handle more power.

Zener diodes are diodes that make use of the breakdown voltage when applying voltage the “wrong” way. They act as voltage regulator.

You have to apply voltage in the “right” direction – from positive to negative – for the diode to start conducting. Usually this voltage is around 0.7V.

If you apply a enough voltage in the “wrong” direction, the diode will break down and current will pass in this direction also.

ZENER DIODE:

These diodes are operated in reverse bias mode, as the reverse bias is increased the resistance remains constant until a certain value known as avalanche point is reached due to avalanche effect the current suddenly increases and the voltage across it becomes almost constant.

Characteristic of Zener Diode

Zener voltage may vary from as little as 3 volt to 150 volts depending on the way the Zener is manufactured. It is used as the voltage regulator.

TRANSISTOR

TRANSISTOR: - is also a semiconductor device used for amplification and sometimes rectification. There are two types of Transistor: - NPN and PNP.

In NPN transistor a small input current and a positive voltage applied in its base (with VB>VE). This allows a large current to flow from collector to emitter.– In PNP transistor a small output current and a negative voltage is applied in its base (with VB<VE). It allows a much larger current to flow from emitter to collector.

The transistor may be taken as a switch controlled by an electrical signal.

If you put about 0.7 volts between the base and the emitter, it turns the transistor on.

Note that this is true for NPN transistors and PNP transistor.

But, instead of two states (ON or OFF), it can also turn on by controlling the base current.

A bit of current on the base produces a current about100 times more (depending on the transistor) through the Collector and Emitter. We can use this effect to build amplifiers.

Let’s look at an example

In circuit above you can see how transistors work. A 9V battery connects to an LED and a resistor. But it connects through the transistor. This means that no current will flow though LED circuit until the transistor turns ON.

To turn the transistor ON you need to apply 0.7V from base to emitter of the transistor. Imagine you have a small 0.7V battery. (In a practical circuit you would use resistors to get the correct voltage from voltage source).

When you apply the 0.7V battery from base to emitter, the transistor turns ON. This allows current to flow from the collector to the emitter. And the LED is turned on and glows.

Here transistor acts as switch.

A Bipolar NPN Transistor Configuration

The most commonly used transistor configuration is the NPN Transistor.

The junctions of the bipolar transistor can be biased in one of three different ways – Common Base, Common Emitter and Common Collector.

Here bipolar transistors is used at the “Common Emitter” configuration using the Bipolar NPN Transistor with an example of the construction of a NPN transistor along with the transistors current flow characteristics is given above.

The construction and terminal voltages for a bipolar NPN transistor are shown above. The voltage between the Base and Emitter ( V_BE ), is positive at the Base and negative at the Emitter because for an NPN transistor the Base terminal is always positive with respect to the Emitter. Also the Collector supply voltage is positive with respect to the Emitter ( V_CE ). So for a bipolar NPN transistor to conduct the Collector is always more positive with respect to both the Base and the Emitter.

NPN Transistor Connection

The voltage sources are connected to an NPN transistor as shown. The Collector is connected to the supply voltage V_CC via the load resistor, RL which also acts to limit the maximum current flowing through the device. The Base supply voltage V_B is connected to the Base resistor R_B, which again is used to limit the maximum Base current.
So in a NPN Transistor it is the movement of negative current carriers (electrons) through the Base region that constitutes transistor action, since these mobile electrons provide the link between the Collector and Emitter circuits. This link between the input and output circuits is the main feature of transistor action because the transistors amplifying properties come from the consequent control which the Base exerts upon the Collector to Emitter current.

PNP Transistor

A PNP Transistor Configuration

(Note: Arrow indicate the emitter and conventional current flow, “in” for a PNP transistor.)

The PNP Transistor is the exact opposite to the NPN Transistor device we looked at in the previous tutorial.

Basically, in this type of transistor construction the two diodes are reversed with respect to the NPN type giving a Positive-Negative-Positive type of configuration, with the arrow which also defines the Emitter terminal this time pointing inwards in the transistor symbol.

Also, all the polarities for a PNP transistor are reversed which means that it “sinks” current into its Base as opposed to the NPN transistor which “sources” current through its Base. The main difference between the two types of transistors is that holes are the more important carriers for PNP transistors, whereas electrons are the important carriers for NPN transistors.

Then, PNP transistors use a small base current and a negative base voltage to control a much larger emitter-collector current. In other words for a PNP transistor, the Emitter is more positive with respect to the Base and also with respect to the Collector.

The construction of a “PNP transistor” consists of two P-type semiconductor materials either side of an N-type material as shown below.

The construction and terminal voltages for an NPN transistor are shown above. The PNP Transistor has very similar characteristics to their NPN bipolar cousins, except that the polarities (or biasing) of the current and voltage directions are reversed for any one of the possible three configurations Common Base, Common Emitter and Common Collector.

PNP Transistor Connection
The voltage between the Base and Emitter ( V_BE ), is now negative at the Base and positive at the Emitter because for a PNP transistor, the Base terminal is always biased negative with respect to the Emitter.
Also the Emitter supply voltage is positive with respect to the Collector ( V_CE ). So for a PNP transistor to conduct the Emitter is always more positive with respect to both the Base and the Collector.
The voltage sources are connected to a PNP transistor are as shown. The Emitter is connected to the supply voltage V_CC with the load resistor, RL which limits the maximum current flowing through the device connected to the Collector terminal. The Base voltage V_B which is biased negative with respect to the Emitter and is connected to the Base resistor R_B, which again is used to limit the maximum Base current.
To cause the Base current to flow in a PNP transistor the Base needs to be more negative than the Emitter (current must leave the base) by approx 0.7 volts for a silicon device or 0.3 volts for a germanium device with the formulas used to calculate the Base resistor, Base current or Collector current are the same as those used for an equivalent NPN transistor and is given as.

We can see that the fundamental differences between a NPN Transistor and a PNP Transistor is the proper biasing of the transistors junctions as the current directions and voltage polarities are always opposite to each other. So for the circuit above: Ic = Ie – Ib as current must leave the Base.

Usage in circuits

It is most important components in computers. Transistors can switch on small electric currents and off. A small base current can increase “main current” which flows through collector to emitter. Thereby, the transistor can amplify a signal. When transistors work as amplifiers it can boost the volume of sounds in audio devices. The transistor is the most important single component in electronics.

It can transform small electric currents into much larger ones. Transistors that work as switches act as the memories in computers, Transistors make up logic gates which make up all digital electronics such as a microprocessor in a computer, laptop, mobile etc. Build several different circuits where the transistor acts as a switch. Like the LDR circuit.

After completing this step you should know how to control motors, buzzers or lights with the transistor.

And you will learn how you can use the transistor to sense. temperature or light.

How To Make Your Own Printed Circuit Boards

To make a printed circuit board you need to:

1.Design schematics

2.Draw the circuit board layout

3.Get the board made

Schematic Diagrams

To make any electronic circuit, you start with a schematic diagram. A schematic is a drawing of a circuit. It tells you which components are needed and how to connect these components.

schematic

You can either design your own schematics or find free schematics available.

Designing schematics

There is some basic electronics theory you should know when designing schematics.

You should at least know how to work with series and parallel circuits.

And it’s really useful to know the basic electronics formulas:

Ohm’s law

Thevenin’s Theorem

Kirchhoff’s Current Law and Voltage Law

Ohm’s law describes the relationship between current, voltage and resistance. This lets you calculate the correct resistor values you need for different parts of your circuit. V= R x I

Thevenin’s theorem explains how you can simplify complicated circuits to make it easier to do calculations.

Kirchhoff’s current law states that the sum of all currents going in and out of a node is equal to 0. You’ll see resistors everywhere. As the name suggests, they resist the current.

You use the resistor to control the voltages and the currents in your circuit.

By using Ohm’s law you calculate current

Suppose you have a 9V battery and you want to turn on a Light-Emitting Diode (LED).

If you connect the battery directly to the LED, Much current will flow through the LED. So the LED will become very hot and burn out after a short time.

But – if you put a resistor in series with the LED, you can control how much current going through the LED. In this case we call it a current limiting resistor.

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Designing Circuit Boards

From the schematics shown above, you design the circuit board. You do this by drawing the wires from the schematics and placeholders for the different components.

PCB . PCBs PCBs

Then you create your circuit board. You aiso can purchase. When your circuit board is created in PCB or breadboard, you solder your components on to the board.. Your electronic circuit is complete. There are many different methods for mounting printed circuit boards. The simplest method is using machine screws and spacers.

An example of a printed circuit board, or PCB, is shown below.

This board has copper-side-up: the side where all the soldering is done. Each hole is ringed with a small layer of copper for bonding to the solder. All holes are independent of each other on the board, but the holes on a solderless breadboard are connected together in groups of five. ?

Printed circuit board (PCB) have traces of copper laid down on the fiberglass board which function as wires in circuit.

A board is shown here, this unit is a “power supply” circuit designed to take 230 volt alternating current (AC) power from household socket and transform it to low-voltage AC which is converted to direct current (DC) by rectifier. There is a resistor on this board, the fifth component counting up from the bottom, located in the middle-right area of the board.

A view of this board’s underside reveals the copper “traces” connecting components together, as well as the silver-colored deposits of solder bonding the component leads to those traces:

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Designing Circuit Boards

From the schematics shown above, you design the circuit board. You do this by drawing the wires from the schematics and placeholders for the different components.

Broadboad

Then you create your circuit board When your circuit board is created in PCB or breadboard, you solder your components on to the board.. Your electronic circuit is complete.

Opto-electronic (optical electronic) components

There are many components that can turn light into electricity or vice-versa. Photocells (also known as photoelectric cells) generate tiny electric currents when light falls on them and these are used as "magic eye" beams in many types of sensing equipment, including some kinds of smoke detector.

Light-emitting diodes (LEDs) work in opposite way, it converts small electric currents into light. LEDs are typically used on the instrument panels of stereo equipment. Liquid crystal displays (LCDs) are in flat screen LCD televisions and laptop computers, are more sophisticated examples of opto-electronics. In LED TVs, as indicator of power supply.

Photo: An LED mounted in an electronic circuit. This is one of the LEDs that makes red light inside an optical computer mouse.

Essential tools for electronic works

(MULTMETER)

Essentials tools; Twizer, cutter, nose plier etc

Wire Cutters - Also called 'side cutters' these are used for cutting component leads close to the circuit board after soldering. I suggest 'Snip Cutter' or '155mm Side Cutters.

Wire Strippers - These are used to strip the insulation off wires

you connect to your circuit. Ic pler

Pliers- Used for bending wires on components to fit into circuit board. These MUST be small, 'Miniature Long Nose Pliers'. Used for bending wires on components to fit into circuit board. These MUST be small - not the ones you use for plumbing! The range of pliers available is vast - I suggest the 'Miniature Long Nose or similar

Plier Twizer Nose plier

Screwdrivers –These are needed for some kits. A small straight type and Medium cross - point type are most useful. pre Precision screw driver

sicion screw drivers

Multimeter - almost essential for all but the absolute beginner.

Power Supply - Also very useful for giving power in circuits that you are testing. One with a variable voltage up to at least 12V is best. The current rating doesn't need to be that high; 1A maximum is fine for most jobs. If possible you can get one with an adjustable current limit - set right that it can prevent damage to an incorrect circuit.

(IC opener) Hi IC quality precision screwdriver set High quality precision screwdriver set

h quality precision screwdriver set

Optional Extras

Soldering iron stand - Stops you burning yourself, the lead or the table when the iron is not in use! Also has a sponge to clean the iron.

Desoldering tool - Useful when you want remove a solder joint for any reason. They work by sucking the molten solder into the pump, away from the joint. (code FR26D)

Wooden board - If you don't have a workbench, use an old piece of shelving or similar to protect your table. If you don't have a board, buy a piece of chipboard or conti - board.

Test equipment - The only test equipment that's required useful at this stage is a multimeter. Now we've sorted out tools,

let’s look at basic techniques starting with soldering.

Beginners Guide – Soldering

Solder - Solder comes in different thicknesses, 22SWG is thinner than 18SWG and is better for small joints. Lead based solder in most commercially built electronic equipment is not allowed, but you can still use it for home project construction. A small tube of lead-free solder should be used. Soldering Iron with stand and sponge

Wire

25W Soldering Iron with Conical Tip

Desoldering tool - Useful when you need to remove a solder joint for whatever reason. They work by sucking the molten solder into the pump, away from the joint.

Wooden board - If you don't have a workbench, use a piece of wooden board to protect your table. If you don't have a board, buy a piece of chipboard.

Test equipment - The only item of test equipment that's worth considering at this stage is a multimeter.

Solder wirei - Solder comes in different thicknesses, 22SWG is thinner than 18SWG and is better for small joints. Get either 60/40 or 63/37 solder where these numbers are the ratio of tin to lead (e.g. 63% tin, 37% lead). 0.8mm solder wire can also be used but 0.5mm solder wire is preferred

Soldering iron –A soldering iron may be needed even if you are building electronic breadboard circuits.

Soldering irons used in electronics are usually in the 15W to 25W range (15 to 25 Watts). They will come with either a small chisel tip or conical tip.

Soldering iron stand - Stops you burning yourself, the lead or the table when the iron is not in use! Also has a sponge to clean the iron.

You will need a soldering iron stand with a sponge. The stand keeps the iron from burning anything on your desk while you are heating it up or using it. The sponge is wet with water and then squeezed out. It is used to clean the soldering iron tip while soldering.

So, when you've got a kit and some tools, you are ready to start. When you're buying the kit get a few spare resistors and some small cuts of strip board for practice soldering. When you've got all these it's time to get some soldering practice.

How to Solder

Plug in the iron and wait about 5 minutes for it to heat up. Place it on something that will not burn, and make sure the 'bit' isn't touching anything and the mains lead. Ideally use a stand.

Tin the bit - melt a small amount of solder onto the tip and wipe the hot iron on a wet sponge. If you don't have a stand with sponge a separate cellulose sponge will do. Do not use synthetic sponge. Make sure the sponge is damp; don’t use dry- that will not clean the tip. This will put a layer of solder on the tip.

Bend the leads on the component with pliers to fit the board. Insert it into the board from the side without copper strips and bend the leads outwards on the other side to hold it in.

Place the tip of the iron on the lead where it comes through the board on the side with the copper strips. Make sure it touches the lead and the board.

Wait a second or two for the board and the lead to heat up. Don't leave it too long or you will damage the component. This is particularly important with semiconductors - transistors, diodes, I.C.'s etc.

Feed the solder into the joint until it forms a ring around the wire. It should stick properly to both the lead and the copper strip on the board. DO NOT carry the solder to joint on the tip of the iron, this almost invariably produces a bad joint.

Remove the iron and allow the joint to cool naturally. DO NOT cool it by blowing on it. The joint should look volcano shaped with the lead sticking out of the board. If it is not shiny, or has formed into a blob then you have made a 'dry' joint. If the joint is not complete re-apply the iron and add a bit more solder.

If you need to remove the solder, use a de-soldering pump or melt the solder and tap the edge of the board on to knock it off. Try again - practice makes perfect! Flush

When the joint is OK, use side cutters to cut the component lead. Repeat the process for the other leg(s) of the component.

When you've finished soldering, clean the tip on the damp sponge and then re-tin it with fresh solder before you unplug the iron. This protects the tin plating on the tip and prevents it oxidizing. Remember to keep the bit away from anything that it could melt until it is completely cold.

Common Problems.

Electronic equipment that you buy in shops uses circuit boards that are made automatically in factories. The exact layout of the circuit is printed chemically on a a plastic board, with all the copper strips made automatically during the manufacturing process. Components are then simply pushed through pre-drilled holes and fastened into place with a kind of electrically conducting adhesive known as solder.

Too little solder - joint not complete, physically weak, possible not electrically sound either. Re-apply the iron and add a bit more solder.

Too much solder - joint will form into a blob, solder may bridge between strips on the board. Remove ALL the solder as described above and try again

Solder will not stick - component lead and / or board may be greasy or dull. Generally you should clean the lead and the board before soldering them. Ideally keep the board in an airtight container when not working on it to prevent oxidisation of the surface.

Don't rush to start building the project until you are sure you can make good solder joints, as you will only spend more time later de-soldering bad joints, and may damage the components. When soldering become good, it's time to start construction.

Beginners Guide - Testing & Troubleshooting

Before you apply power, read the instructions carefully to check you haven't missed anything, and whether there are any specific instructions for switching on and testing. Check again that you have connected polarity of component properly and that all components are in the correct places. Check off - board components are connected correctly. Check the underside of the board carefully for short circuits between tracks - a common reason for circuits failing to work.

DOUBLE-CHECK THE POLARITY OF THE BATTERY AND ANY POLARISED COMPONENTS, capacitor.

When you are sure everything is correct, apply power and see if the circuit behaves right.

If it doesn't quite work as expected, or doesn't work at all, don't despair. The chances are the fault is quite simple. However, disconnect the power before reading on.

Check the basic's first - is the battery flat? Are you sure the 'On' switch really is on? (Don't laugh, it's easily done) If the project has other switches and controls check these are set correctly.

Next - check again all the components are in the correct place - refer to the diagram in the instructions. Look again at the underside of the board - are there any short circuits? These can be caused by almost invisible bad solder, so check for these with a magnifying glass in good light. Brushing the bottom of the board vigorously with a stiff brush can sometimes remove these.

Pull the components gently to see if they are all fixed into the board properly. Check the soldered joints - poor soldering is the most common cause of circuits failing to work. The joints should by shiny, and those on the circuit board should be volcano shaped with the component wire end sticking out of the top. If you look suspect then redo them. Remove the solder with a solder sucker or braid and try again.

Check for solder splashes shorting adjacent tracks on the circuit board, specially where connections are very close such as on integrated circuits ('chips'). You can check for shorts using a multimeter set it to it's continuity range, or low resistance range. Any resistance below 1 ohm between tracks is likely to be a solder splash. Run the soldering iron between tracks on stripboard to remove any solder bridges.

If the circuit still fails to work you will need to refer to the circuit diagram and take voltage readings from the circuit to find out what's wrong. Use a multimeter to do this. Remember that if you find one fault such as a reversed component and correct it, it might have caused damage to other components.

Electronics around us

Electronics is now so widespread that everybody is using all for for entertainment purposes. Electronic gadgets like AM/FM Radio, DVD player, Blue Ray Player and television of various types like LED TV, have developed due to miniaturization and growth of electronic industry. Mobile phone has developed vastly and is widely being used by people. About 11million mobile phone are being used now in India. Internet is also widely used in mobiles phones and computers and laptop and all are benefited from internet, sophisticated digital electronics.

You will not find anything you do that doesn't involve electronics. Your car engine probably has electronic circuits in it—you may have car stereo antenna amplifier and also the GPS satellite navigation device that tells you where to go? Even the airbag in your steering wheel is triggered by an electronic circuit that detects when you need some extra protection.

Electronic equipment saves our lives. Hospitals are using all kinds of electronic gadgets, from heart-rate monitors and ultrasound scanners to complex brain scanners and X-ray machines. Hearing aids gadgets get benefit from the development of tiny transistors, and very small integrated circuits have make hearing aids to become smaller and more powerful at present.

Aerial - picks up radio signals from many stations.

Tuner - selects the signal from just one radio station.

Detector - extracts the audio signal carried by the radio signal.

Audio Amplifier - increases the strength (power) of the audio signal. This could be broken down into the blocks like the Audio Amplifier System shown above.

Loudspeaker - a transducer which converts the audio signal to sound., in your car and in many others.

And you can find many different types of LEDs. A very common circuit to build as a beginner is the blinking light circuit. to ac

ircuit, (and the correct-value resistor is included), a voltage will be develop across the LED called the CHARACTERISTIC VOLTAGE DROP. This voltage is due to the colour of the LED and the crystal inside the LED that produces the colour. The diagram above shows the approximate voltage developed for each LED. The voltage does not change for small, medium, surface-mount, or large LEDs.

LEDs in series and parallel.

Connecting LEDs in parallel

illuminate.

Figure- COMPONENTS

How To Make Your Own Printed Circuit Boards

To make a printed circuit board you need to:

1.Design schematics

2.Draw the circuit board layout

3.Get the board made

Schematic Diagrams

To make any electronic circuit, you start with a schematic diagram. A schematic is a drawing of a circuit. It tells you which components are needed and how to connect these components.

schematic

You can either design your own schematics or find free schematics available.

Designing schematics

There is some basic electronics theory you should know when designing schematics.

You should at least know how to work with series and parallel circuits.

And it’s really useful to know the basic electronics formulas:

Ohm’s law

Thevenin’s Theorem

Kirchhoff’s Current Law and Voltage Law

Ohm’s law describes the relationship between current, voltage and resistance. This lets you calculate the correct resistor values you need for different parts of your circuit. V= R x I

Thevenin’s theorem explains how you can simplify complicated circuits to make it easier to do calculations.

Kirchhoff’s current law states that the sum of all currents going in and out of a node is equal to 0. You’ll see resistors everywhere. As the name suggests, they resist the current.

You use the resistor to control the voltages and the currents in your circuit.

By using Ohm’s law you calculate current

Suppose you have a 9V battery and you want to turn on a Light-Emitting Diode (LED).

If you connect the battery directly to the LED, Much current will flow through the LED. So the LED will become very hot and burn out after a short time.

But – if you put a resistor in series with the LED, you can control how much current going through the LED. In this case we call it a current limiting resistor.

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Designing Circuit Boards

From the schematics shown above, you design the circuit board. You do this by drawing the wires from the schematics and placeholders for the different components.

PCB . PCBs PCBs

An example of a printed circuit board, or PCB, is shown below.

Printed circuit board (PCB) have traces of copper laid down on the fiberglass board which function as wires in circuit.

A view of this board’s underside reveals the copper “traces” connecting components together, as well as the silver-colored deposits of solder bonding the component leads to those traces:

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Designing Circuit Boards

From the schematics shown above, you design the circuit board. You do this by drawing the wires from the schematics and placeholders for the different components.

Broadboad

Then you create your circuit board When your circuit board is created in PCB or breadboard, you solder your components on to the board.. Your electronic circuit is complete.

Opto-electronic (optical electronic) components

There are many components that can turn light into electricity or vice-versa. Photocells (also known as photoelectric cells) generate tiny electric currents when light falls on them and these are used as "magic eye" beams in many types of sensing equipment, including some kinds of smoke detector.

Light-emitting diodes (LEDs) work in opposite way, it converts small electric currents into light. LEDs are typically used on the instrument panels of stereo equipment. Liquid crystal displays (LCDs) are in flat screen LCD televisions and laptop computers, are more sophisticated examples of opto-electronics. In LED TVs, as indicator of power supply.

Photo: An LED mounted in an electronic circuit. This is one of the LEDs that makes red light inside an optical computer mouse.

Essential tools for electronic works

(MULTMETER)

Essentials tools; Twizer, cutter, nose plier etc

Wire Cutters - Also called 'side cutters' these are used for cutting component leads close to the circuit board after soldering. I suggest 'Snip Cutter' or '155mm Side Cutters.

Wire Strippers - These are used to strip the insulation off wires

you connect to your circuit. Ic pler

Plier Twizer Nose plier

Screwdrivers –These are needed for some kits. A small straight type and Medium cross - point type are most useful. pre Precision screw driver

sicion screw drivers

Multimeter - almost essential for all but the absolute beginner.

(IC opener) Hi IC quality precision screwdriver set High quality precision screwdriver set

h quality precision screwdriver set

Optional Extras

Soldering iron stand - Stops you burning yourself, the lead or the table when the iron is not in use! Also has a sponge to clean the iron.

Desoldering tool - Useful when you want remove a solder joint for any reason. They work by sucking the molten solder into the pump, away from the joint. (code FR26D)

Wooden board - If you don't have a workbench, use an old piece of shelving or similar to protect your table. If you don't have a board, buy a piece of chipboard or conti - board.

Test equipment - The only test equipment that's required useful at this stage is a multimeter. Now we've sorted out tools,

let’s look at basic techniques starting with soldering.

Beginners Guide – Soldering

Wire

25W Soldering Iron with Conical Tip

Desoldering tool - Useful when you need to remove a solder joint for whatever reason. They work by sucking the molten solder into the pump, away from the joint.

Wooden board - If you don't have a workbench, use a piece of wooden board to protect your table. If you don't have a board, buy a piece of chipboard.

Test equipment - The only item of test equipment that's worth considering at this stage is a multimeter.

Soldering iron –A soldering iron may be needed even if you are building electronic breadboard circuits.

Soldering irons used in electronics are usually in the 15W to 25W range (15 to 25 Watts). They will come with either a small chisel tip or conical tip.

Soldering iron stand - Stops you burning yourself, the lead or the table when the iron is not in use! Also has a sponge to clean the iron.

So, when you've got a kit and some tools, you are ready to start. When you're buying the kit get a few spare resistors and some small cuts of strip board for practice soldering. When you've got all these it's time to get some soldering practice.

How to Solder

Plug in the iron and wait about 5 minutes for it to heat up. Place it on something that will not burn, and make sure the 'bit' isn't touching anything and the mains lead. Ideally use a stand.

Bend the leads on the component with pliers to fit the board. Insert it into the board from the side without copper strips and bend the leads outwards on the other side to hold it in.

Place the tip of the iron on the lead where it comes through the board on the side with the copper strips. Make sure it touches the lead and the board.

If you need to remove the solder, use a de-soldering pump or melt the solder and tap the edge of the board on to knock it off. Try again - practice makes perfect! Flush

When the joint is OK, use side cutters to cut the component lead. Repeat the process for the other leg(s) of the component.

Common Problems.

Too little solder - joint not complete, physically weak, possible not electrically sound either. Re-apply the iron and add a bit more solder.

Too much solder - joint will form into a blob, solder may bridge between strips on the board. Remove ALL the solder as described above and try again

Beginners Guide - Testing & Troubleshooting

DOUBLE-CHECK THE POLARITY OF THE BATTERY AND ANY POLARISED COMPONENTS, capacitor.

When you are sure everything is correct, apply power and see if the circuit behaves right.

If it doesn't quite work as expected, or doesn't work at all, don't despair. The chances are the fault is quite simple. However, disconnect the power before reading on.

Electronics around us

Aerial - picks up radio signals from many stations.

Tuner - selects the signal from just one radio station.

Detector - extracts the audio signal carried by the radio signal.

Audio Amplifier - increases the strength (power) of the audio signal. This could be broken down into the blocks like the Audio Amplifier System shown above.

Loudspeaker - a transducer which converts the audio signal to sound.

PagesAndroid Kitkat,Lollipop and Marshmallow Mobile

Tuesday 13 December 2016

Electronics for Beginners

A parallel resistor short-cut

You have three resistors in parallel, with values 6 ohms, 9 ohms, and 18 ohms. The smallest resistance is 6 ohms, so the equivalent resistance must be between 2 ohms and 6 ohms (2 = 6 /3, where 3 is the number of resistors).

Doing the calculation gives 1/6 + 1/12 + 1/18 = 6/18. Making this upside down gives 18/6 = 3 ohms, which is certainly between 2 and 6.

Remember that for resistors in series, the current is the same for each resistor, and for resistors in parallel, the voltage is the same for each one.

Circuits with series and parallel components

The capacitor is often used to introduce a time-delay in a circuit, for example to blink a light. It’s commonly used for removing noise and makes DC voltage of a circuit stable. Using Capacitors For Filters

Now you can try to understand some components. Two types of semiconductor material are there which known as P - type and N – types of semiconductors such as silicon and germanium.

A Bipolar NPN Transistor Configuration

PNP Transistor

A PNP Transistor Configuration

How To Make Your Own Printed Circuit Boards

But – if you put a resistor in series with the LED, you can control how much current going through the LED. In this case we call it a current limiting resistor.

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Designing Circuit Boards

From the schematics shown above, you design the circuit board. You do this by drawing the wires from the schematics and placeholders for the different components.

Opto-electronic (optical electronic) components

There are many components that can turn light into electricity or vice-versa. Photocells (also known as photoelectric cells) generate tiny electric currents when light falls on them and these are used as "magic eye" beams in many types of sensing equipment, including some kinds of smoke detector.

(MULTMETER)

Essentials tools; Twizer, cutter, nose plier etc

Optional Extras

So, when you've got a kit and some tools, you are ready to start. When you're buying the kit get a few spare resistors and some small cuts of strip board for practice soldering. When you've got all these it's time to get some soldering practice.

Too little solder - joint not complete, physically weak, possible not electrically sound either. Re-apply the iron and add a bit more solder.

Too much solder - joint will form into a blob, solder may bridge between strips on the board. Remove ALL the solder as described above and try again

Beginners Guide - Testing & Troubleshooting

DOUBLE-CHECK THE POLARITY OF THE BATTERY AND ANY POLARISED COMPONENTS, capacitor.

How To Make Your Own Printed Circuit Boards

But – if you put a resistor in series with the LED, you can control how much current going through the LED. In this case we call it a current limiting resistor.

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Electronic circuits

The key to an electronic device is not just the components it contains, but the way they are arranged in circuit.

Designing Circuit Boards

From the schematics shown above, you design the circuit board. You do this by drawing the wires from the schematics and placeholders for the different components.

Opto-electronic (optical electronic) components

There are many components that can turn light into electricity or vice-versa. Photocells (also known as photoelectric cells) generate tiny electric currents when light falls on them and these are used as "magic eye" beams in many types of sensing equipment, including some kinds of smoke detector.

(MULTMETER)

Essentials tools; Twizer, cutter, nose plier etc

Optional Extras

So, when you've got a kit and some tools, you are ready to start. When you're buying the kit get a few spare resistors and some small cuts of strip board for practice soldering. When you've got all these it's time to get some soldering practice.

Too little solder - joint not complete, physically weak, possible not electrically sound either. Re-apply the iron and add a bit more solder.

Too much solder - joint will form into a blob, solder may bridge between strips on the board. Remove ALL the solder as described above and try again

Beginners Guide - Testing & Troubleshooting

DOUBLE-CHECK THE POLARITY OF THE BATTERY AND ANY POLARISED COMPONENTS, capacitor.

No comments:

Post a Comment