555 TIMER AND CIRCUIT APPLICATIONS (NE555, LM555)

555 Timer Integrated Circuit are commonly use in L.E.D Sequencer, Clock Generator also known as Oscillator and in basic electronics practice. They are usually known as Timer I.C; sometimes hobbyist calls it 555 Timer.
555 Timer are widely use in the field of electronics such as in Laptops, TV, and Timer Circuits (Bomb Trigger Circuit) and so on. In Digital Clocks, Indicators requiring flashing operations, in L.E.D Sequencer use in Christmas displays and lots more down to complex applications in electronics design. Today, I shall only introduce you to basic applications of Timer Integrated Circuit and configurations (Ways of Application)
.

AS A MONOSTABLE

555 Timer can be connected to operate as a Monostable Flip-flop. As the name implies, it is a multivibrator that has only one (mono) stable state. That is to say, when it is been triggered whether intentional or unintentionally, it changes its state (output) and then later returns back to its original state where it was before it was triggered. In a way, its like saying when a monostable timer is triggered, its output changes state from Low (0) to High (1) where the Low represents the absence of a voltage or signal and the High represents the presence of a voltage or signal.

Below is a way to connect the terminals of a 555 Timer to operate or function as a Monostable flip-flop. Its pin 2 is the trigger pin, pin 3 remains the output pin, pin 6 is connected to pin 7 and a frequency determining network (RC Network) is connected between pin 7 and Vcc (Power supply line) and the Ground (0v). Remember that pin 4 and pin 8 is always connected to the supply rail (Power supply line) and pin 1 is always connected to Ground (0v).

The output of this circuit can be connected to drive a Relay, an L.E.D, and a Buzzer and so on. Note the Trigger pin (pin 2) must not or is not advisable to be left floating (unconnected) so as not to be falsely triggered by stray alternating signals around, even from your hands close to the trigger pin can cause it to be triggered. Therefore, you could connect a load resistor between pin 2 and supply rail, then having a pull0down switch from pin 2 to ground. This keeps the input of the Timer High, until when pulled down to 0v (Ground) by the switch before it triggers the circuit.

AS AN ASTABLE MULTIVIBRATOR (OSCILLATOR OR CLOCK GENERATOR)

A 555 Timer connected as an oscillator or astable multivibrator operates on a free-run ground. What I meant is, it does not require your effort to cause it to oscillate (or trigger unlike a Monostable). Once the power source is powered ON, it begins to oscillate (ON and OFF alternatively and continuously) except the power source is disconnected or switch-Off.

There are cases we need this kind of operation. In events or situation where we need a clock pulse (oscillation) to be triggering our circuit independently and continuously, we then apply a 555 Timer connected as an oscillator. Please note that the waveform (wave shape) produce by a 555 Timer is a pulsing or square like waveform. This MUST not be mistaken or assumed to be a Sine Wave!

Below is a practical oscillator circuit with actual values that you can experiment with.

In 555 Timer been use as an oscillator, pin 2 is connected with pin 6, pin 4 and pin 8 is connected to the supply rail as usual as seen in the above diagram. Pin 1 is connected to 0V (Ground), Pin 3 is our Output terminal. A capacitor (say C) is connected between Pin 6 (along side pin 2) and Ground. A resistor (say R2) is connected between pin 6 and pin 7, another resistor (say R1) is connected between pin 7 and supply rail (or pin 8 and pin 4 since they both are also connected to the supply rail). The output been pin 3 could be connected to drive any load say a Relay that could in turn operate a contact to switch ON a Motor, Fan, Conveyor, Lamp, L.E.D and so on. Below shows a practical configuration and values of component use in constructing an oscillating circuit.

Ping me a mail if you have any question or assistance regarding the discussion above. I shall be there to attend to you ASAP!

Thanks for taking time to read! You are wonderful! Let’s make it a date again tomorrow, as I hope to furnish you with another interesting package. Don’t miss it!

Isaac Johnson

Circuit Design And Technology

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HOW TO CONSTRUCT A LED SEQUENCER USING CD4017

In my recent article I discuss how to use a Decade counter popularly known as CD4017 (Divide by 10) to switch a lamp or load. In this article, we shall look into how to still use a decade counter 4017 to drive series of L.E.D to form a circle, a pattern or a line etc pending on your desire.

Recall that a decade counter (also known as divide-by-10) has 10 outputs. These outputs can sink a current required to operate a L.E.D. But since we want the operation to be sequential i.e. coming on and off one after the other in ascending or descending pattern, we therefore would need another stage that will be generating a steady pulse or oscillation for us to clock the counter.

Knowing what we want, we will go for a clock generating Integrated Circuit. So far, the basic simplest bone is NE555 popularly known as a Timer I.C or Timer. In my coming article I shall discuss 555 Integrated Circuits in details.

NE555 is an 8 terminal I.C with RC (Resistor-Capacitor Network) frequency determining arrangement. The connection of 555 will determining its application as it can also be use as a Monostable Multivibrator (One-Shot Trigger). In this discussion, we shall be using it as a clock generator r oscillator to provide is a stable pulse to serve as our trigger to the counter independent of an operator manually triggering the unit to make a sequence display.

Following my connection as shown bellow, with the right component values, you will be able to construct a Timer and a counter to drive L.E.Ds.

Now, connect a fixed value resistor say 4.7k in between pin 7 and 8 of the 555 I.C.

Next, connect a 1k resistor in series with a variable resistor of 100k in between pin 7 and pin 6.

Next, connect a 10 uF capacitor in between pin 6 and pin 1 of the 555 I.C.

Next, link pin 2 of the 555 timer to pin 6 using a jumper or conductor.

Next, connect pin 4 and pin 8 of the 555 timer to your supply rail (Power supply line).

Next, connect pin 1 of the 555 timer to ground (0 V) and pin 5 of the timer should be connected with a

100nF

capacitor to ground (0v). You can check my article on Capacitors in Blog Archives for tutorials how to identify and know capacitors.

Next, your pin 3 is now your output. You should get oscillating pulse from here if you follow my instructions above.

Now, we need to fix the counter Unit. You could also check the Archives by the left pane of this site on how to use a decade counter as a switch for familiarity sake.

Now, just follow my connections as seen below, by connecting pin 8 and pin 13 of the counter 4017 to ground (0V).

Next, connect pin 16 to supply rail (power supply line). Connect pin 14 (clock input) to the pin 3 of the 555 timer. With this, you should have all your counters output jumping up and down sequentially. So, we just need to connect our LEDs to the outputs as shown below. Also, I shall give you more tutorials on LED soon ok!

Lets make it a date tomorrow as I hope to bring another information package your way again. You are special!

Isaac Johnson

Circuit Design And Technology

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How to Read (Test) or Detect a Transistor Terminal

How to Read (Test) a Transistor Using Multimeter

In basic electronics, the know-how or ability to read or been able to detect a transistor terminals is very important as knowing what to do with it. Without knowing or determining the position of individual terminals, you can’t use it properly. You might even end up feeding it with excessive current beyond its rated value and thereby damaging the transistor in the process.

In this discussion I shall show you basic and direct ways to detect a transistor terminal. Also, the diagrams inclusive will guide you so to know what the text is about.

Requirement

First, you would need to have a Multimeter. Below shows a basic Multimeter. Rotate the knob of the multimeter to “Diode” range as seen in the diagram below. The "Diode range" has a "Diode symbol" drawn on it

Secondly, connect your multimeter probe (Red and Black) to any two terminal of your choice. Why I said so is, we need to pick terminal randomly to locate which of the terminals has the highest resistance compare to the other. Also, we will apply basic Diode characteristics.

Thirdly, check your multimeter reading. Did you get any reading? If no! Interchange the multimeter probe (Red to Black and Black to Red). Did you get any reading? If yes, take note of the reading (say, 600 ohms).

Fourthly, make one of the probe static (fixed) and rotate the other probe. For instance, if you choose to make the Red probe static (fixed), then use the Black probe to connect the other idle terminal that has not been connected. Did you get any reading? If Yes, take note of the reading (say 620 ohms). Comparing these results, the one with the highest resistance is the Emitter. While the other terminal wit less resistance is the Collector and the third terminal is the Base. If your reading was No! Then instead of making the Red probe static, make the Black probe static. Did you get any reading? If yes, compare your reading. The terminal with the highest resistance is the Emitter, while the terminal with the lesser resistance is the Collector. Then the third terminal is the Base.

ALTERNATIVE METHOD

Download basic transistor pin configuration online. For instance, C9014 and C9018 series: there Base is at the middle. The collector is at the right hand side when the transistor is standing upright facing you with its value (name tag) facing you. The Emitter is the last terminal by your left hand side.

For C1815 series, the base is at the last right hand side terminal when the transistor is facing you with its name tag in front standing erect. The next terminal (middle terminal) is the collector, and the last terminal by your left hand side is known as the Emitter. Also, you can use your multimeter to confirm these things I just said.

For BC108, BC109 etc, there usually is a Notch or Protruded edge at one side of the transistor. The edge indicates the Emitter. The next terminal usually the next is the Base and the last terminal is the collector.

Please, feel free to contact me if you have any difficulty locating the terminals of your transistor. I shall be delighted in responding ASAP.

Thanks for your time again, lets make it a date tomorrow.

Isaac Johnson

Circuit Design and Technology

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How To Use A Decade Counter CD4017 To Switch-On Your Bulb

CD4017 is a decade counter

Popularly known as a Divide-by-10 counter. Yet, it can be reconnected to become a Divide-by-2 counter which directly is a Bistable Multivibrator. In using CD4017 Integrated Circuit as a switch, we must know the terminals and basic operations of a decade counter. 4017 is a decade counter that has 10 outputs with 1 input.

When the clock input is triggered by a clock pulse say a voltage (Low to High), its output jumps or advances to the next output. So, in every pulse received, the output advance to the next point until it gets to the 10th output and automatically reset back to the first output. Below is a schematic or diagram showing the pin configuration (connection):

The Pin 8 is connected to the ground, Pin 16 is connected to the Positive Supply rail (VCC) and Pin 15 is the Reset pin. Pin 13 is also connected to Ground (0V) and Pin 14 is the Clock Input to the I.C. The output of the counter are indicated with Pin Numbers 3, 2, 4, 7 and so on as show above in the diagram.

The input of the decade counter is pulled-down with a 470KΩ resistor to eliminate it been false triggered by stray signal or touching of the arms. The Rest pin is connected with an auto-reset network using a capacitor and a resistor to enable it return to its initial start point when the I.C is powered the first time. The 3rd output (Pin 4) is connected or fed back to the reset pin through a Diode to reset the outputs back to the start point when the output advances to the 3rd output. This is to say that, when the counter advances from point 1 to point 2, the next cock pulse will cause it to return back to the first point.

Next, we connect the output of the counter to a transistor. We did this because; the output from the counter is not sufficient enough to drive a relay that will close the contact of our Load. The transistor used in this case is a BC547 transistor used as a driver to energize a relay. We connected the 2nd output of the counter to bias the transistor (provide Base-Emitter voltage) for it to saturate (conduct). The biasing then causes electrons to migrate from the emitter to the collector of the transistor, thereby causing large drain of current from the collector to flow from the Power source (VCC), and through the Relay coil and the collector.

The contact of the relay coil now serves as our Open and Close Switch as it is in our houses. Here we then connect our Load, say an Electric Bulb or Socket of 230V AC from the source to the load with the contact been in series acting as the bridge or switch. Below is the detailed circuit diagram of the whole unit as explained above:

BC547 is not the only transistor that can be use in this case. Others include BC108, BC548, BC547, C1815, C9018, C9014 and lots more. Don’t forget also that aside using a decade counter to function as a switch, decade counters are also use in Frequency Divider, Sequence Display with L.E.Ds and lots more not listed here.

Please find time and check on my article tomorrow for other interesting tips I will disclose to you not discussed today.

Thanks, Isaac Johnson

Circuit Design and Technology

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How To Use a Transistor as a Switch

In my last article I discussed on how to construct basic electronics circuit using principles of diode forward biasing and other components such s capacitor and wire wound resistor base on your desire. Today I want to teach you another pattern that has to do with not just knowing what you want but also constructing basic circuits base on their uses and knowing how to join various component to form what you want.

First, I must apologies for my inability to post article for some few days as I was down health wise. So, back to the discussion of today.

If you know how a transistor operates, you could easily decide on what you could use it for. So, we shall be discussing basic operations of a Transistor, Diode, Capacitor and Resistor.

Transistor:

In my previous article I told you that a transistor is a semiconductor device made of 2 p-n junctions. It could either be a PNP type or an NPN type. The NPN type is mostly use in areas where the supply as in the power source is a positive +VCC while PNP is mostly used in power sources of negative rail –VEE.

A transistor can be use as a switch, as an amplifier, as a gate etc. first, lets start with it been used as a switch.

When you pass little current through the base of a transistor, it causes large amount of current to flow from the collector to the emitter. In order words, we can operate or energize a device or load connected in series between the collector of a transistor and the power source rail (line). Once the base senses a current capable of driving its junction or biasing its base emitter junction, the load connected across its collector will be energize instantly. Below is a simple way of illustrating this in energizing a Bulb of 12v.

As a switch in Logic circuit

, a transistor can be use in applications where you need a 1 (High) and a 0 (Low) signal. High signifies presence of a voltage or signal and Low signifies the absence of a voltage or signal. Below shows a basic arrangement of how it is use as a switch in logic circuit. Note, mostly used transistor types are C1815, BC108, C9018, C9014, BC547, BC548 and so on. The transistor type matters when it comes to power dissipation, current rating, frequency response range, Gain, Temperature range and lots more. Easy! I won’t rush all of them on you ok!

As a Signal Amplifier

, a transistor can be use in amplifying analogue signal such as audio signal from a microphone or an analogue signal generator. Due to the migration of electrons from the emitter to the collector, the higher voltage at the collector will flow down the emitter. That is to say, if we connect a load (which could be a speaker) in series with the collector of the transistor and the supply rail, when a little audio signal fed to the base of the transistor, a large signal will be replicated at the collector which is a capable of even driving an L.E.D or other forms of transducer such as a speaker.

Hmmmmm, i need have a drink and rest a little ok! lets make it a date tomorrow please, i will give you more tips you wont resist. Thanks so much my friends for your time with me. see ya!

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Remote Operated Lighting System

Circuit Design

How to Design Basic Electronics Circuit using Diode, Precision Potentiometer, Capacitor etc

Circuit Design is one of the basic and yet technical aspect of electronics in our schools and life as an electronics hobbyist. As we shall be working with component such as Diode anode cathode,Principles of Diode forward bias, Diode characteristic, Capacitors, Wire Wound Resistors and Precision potentiometer.

The art of electronics and ability to imagine or been creative is an important skill in science. Innovations, ideas, research and persistent has brought about the existence of certain component in engineering and science as a whole. Today, I will be giving you a concept of knowing what you want to do and how to go about it.

For instance, you came back home after the day’s job, tired and hungry. Reaching out to the wall switch to put on your lighting system and television set, it seems it’s another form of work. The thought of having a system where you could just be on your sofa and put on your room lighting system, security light outside, television set and so on.

First, in wanting to construct a unit that will receive infra-red (IR) signal from your TV remote control, you need a component that can receive these IR signal (Infra-red ray), then convert it to switch ON or OFF a relay. Since a relay can be use as a switch, the relay will now serve as the contact-maker or switch-operator for you.

Having gotten an idea of your intention, its time to look for these component. The first stage is the stage that will receive the IR ray, but this stage cant stand alone without a “Pulse stretcher”. A Pulse stretcher is a monostable multivibrator. Once triggered, it remains ON for duration of time determined by the RC-network known as the frequency determining network. This is necessary because the stream of pulse “IR ray” coming from the IR transmitter in the TV remote is a stream of multiple rays oscillating from 300Hz up to 33 KHz depending on certain factor. BUT, we only needed ONE ray to drive the next stage. So, we improvise a stage that will help us eliminate other rays while allowing ONLY on ray to pas through. The output of the second stage (Pulse Stretcher) is then connected to a unit that will be doing the changing of “state” for us. It’s called A Bistable Multivibrator. We will use a decade counter CD4017 connected in such a way as to serve as a Bistable Multivibrator for us. Such that, when it receives a pulse of IR ray, its OUTPUT will be High (ON) or Low (OFF).

This On or off state will be connected to the base of a transistor that will energize a relay. GBAM!!! Simple? Let’s find out

- Infra-Red Receiver

Infra red receiver is common in the market. Below is a popular type of IR Receiver and its pin configuration (arrangement).

As seen from the diagram above, the first pin from your left with the device facing you directly is Pin 1 (Connected to GROUND), Pin 2 (Connected to Positive Supply- VCC) and Pin 3 (Connected as output to the next stage) Output.

So, from my diagram, the terminal of the NAND gate i used, the first pin connected upward is the Positive VCC, The centre connecting to the next stage is Output while the last terminal going Ground is Ground.

The first terminal or pin is tagged “Pin 1”. Pin 1 is the “Ground”. So, during our construction, we will connect pin 1 to the ground or neutral potential of our power supply unit (Battery).

Next, Pin2 is “+V” known as the positive terminal or positive pin for our power supply unit. Also, we shall connect a regulator (Zener Diode) rated at 5.1V to provide a stable voltage not beyond 6V.

Next, Pin 3 (Output) will be connected to the next stage as our source of signal input for that stage.

Below is a circuit diagram with precise and correct component values that has been assembled and tested for quality reason to enable you put something of this form together. I shall be using “Multism 10” in drawing the circuit diagram.

I was unable to get the symbol of IR receiver in Multism 10 component list, so i used a NAND-gate logic circuit symbol in representing IR Receiver. ok! For those of us that doesnt known what a NAND Gate symbol is, its the symbol at the begining of the diagram with a little circle ball at the back connecting to the next stage been the Pulse Stretcher.

Please note that, D1 and K1 are poitns where you will connect your load or socket or Bulb, while the other end is your source of power say PHCN as the case may be.

Dont forget to connect pin 8 of CD4017 to ground and pin 14 to supply (VCC).
Feel free to leave your questions as the need arise.

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Tunnel Diode

A friend of mine asked a question if a Tunnel Diode is same as a Diode. And if no, what is the difference between a diode and a Tunnel diode with likely applications in basic electronics these days.

What is a Tunnel Diode?

In simple term, a tunnel diode is a semiconductor that has a very thin p-n junction as compare to that of a normal diode, such that electrons can yet travel across the insulating material posing as a wall through a

tunnel effect

. Below is a diagram showing a Tunnel Diode:

If you could recall, in developed world mostly, there is a route known as “Tunnel” where motor vehicles and other form of transportation plight through. You will agree with me that such routes are normally situated in areas where there seems to be “No Way” out but there came a way out at the end.

This also is a perspective of mine for which Tunneling is assign to the diode for its uniqueness amongst other forms of semiconductors.

Back to the main issue of the day, a tunnel diode is a semiconductor with a unique and remarkable ability as I earlier stated sighting instance of its ability of maneuverability across a wall of insulation against conventional assumption and operation of a normal diode.

Tunnel Diode was developed by a physicist in Japan known as Esaki Leo around 1985. Its so unique even in respect to the minute power consumption of about 1% as compared to a normal Transistor.

Not only that, experimentally, it has been proven that tunnel diode in addition with a diode could form part of a Frequency Modulation Radio. This is important as it occupies less space and has light weight. Also, it is free from interruption of radiation effects, temperature changes and electrical noises associated with high frequency devices. This is to say that it can operate at frequencies far beyond frequencies a normal transistor can even operate!

Tunnel Diode is also use in satellites systems where high frequencies exist. Also, they are use in portable radio units and ultra high frequency radio communication systems and television systems.

I can’t pulse here without showing you the picture of the man behind this unique discovery or breakthrough. This is areas where I get insight, motivation and hope of not giving up on things in life. Never ever you say it’s over when you yet have air to breath. You can be the next physicist to make something new!

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How to Calculate Capacitance and Identify Capacitors

Types of Capacitors:

In my last article on Capacitor and its applications, I needed include the discussion on how to identify a Capacitor and how to calculate its capacitance for any electronics circuit project.

Capacitor

Capacitor as I discussed in my last article is a two terminal device with a di-electric in-between them serving as an insulator. These insulating medium could be a paste of electrolyte (electrolytic capacitors), paper or even air.

Electrolytic capacitors

are easily identifiable as its ratings (voltage rating and capacitance value) are all written boldly on it. The voltage rating of a capacitor is also known as the maximum voltage or the voltage capability of that capacitor that it can withstand without been damaged (burst, explode or even bridge the entire circuitry).

Also, electrolytic capacitors are known to be such as they have polarity (as in positive and negative terminal). For you to be able to identify the polarity of an electrolytic capacitor, just look at its side, you will notice a demarcated strip of line, sometimes; it could be a broken continuous strip of line. That portion of the terminal is the negative terminal. Because that strip by it denotes the position of the negative terminal of the capacitor. This means that, the other terminal that is left uniformly colored with the rest side of the capacitor is the positive terminal of the capacitor.

Electrolytic capacitors are usually in micro-farad (µF) ranging from low values as 0.01µF to 10,000µF as commonly available in the markets. These types of capacitors do not need calculating their capacitance anymore since it is already indicated by the manufacturer. All you need to know and be concern with is its application. What do you want to do with it and where to insert it on your Printed Circuit Board or Veroboard. Below shows picture of an electrolytic capacitor as commonly available in the market.

Ceramic Capacitor:

Ceramic capacitors are other type of capacitor that has smaller values compared to electrolytic capacitor. These types of capacitors are mostly applied in areas of high frequencies such as in radio frequency applications. They are easily recognized by the digit of number and alphabet written on them as also a variable resistor.

Usually or commonly, you could see something of this sort: 103. This means that the value of the capacitor is 10nF (Nano-farad). The last digit “3” is the multiplier. Also, sometimes you could see something like 103k. This means it is 10pF (10 Pico-farad) where the “k” denotes a multiplier of 10^3.

But also, you could find just “10” written on it meaning its 10pF
. Below is a picture of how a

ceramic capacitor

looks like.

What are your intentions? What do you want to use the capacitor for? All these determine the kind of capacitor to use and not to use. For instance, in building power supply unit for a device that uses a 12v DC or requires a 12v DC output, you MUST not use a capacitor rated at 5V. This will cause the capacitor to overheat and burst or cause a short circuit on your board. This means that you have exceeded the maximum rating of such capacitor specified by the manufacturer.

It is highly recommended to KNOW what type of capacitor you really need at a time and its power requirement needed to withstand your demand. For a 12v supply, I advice you use a capacitor rated at 15v to 18v working voltage (WV).

I wish this discussion goes a long way to answer some of your hidden questions. feel free to leave a comment, suggestions or opinion anytime because I Isaac Johnson is here to serve you. please lets make it a date again tomorrow as i hope to open your mind to another topic.

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CAPACITOR

What is a Capacitor?

A capacitor is a device for storing electrical charges. It consists of two conductors or metal plates separated by an insulating material known as the dielectric. These plates are parallel to each other. The charge stored in a capacitor is proportional to an increase in its conductivity.
When one of the plates is charged with electricity from a direct-current or electrostatic source, the other plate of the capacitor will have an induced charge of the opposite sign. That is to say, if the charge at one of the plate is positive, the other plate will have a negative charge. The amount of electric charge a capacitor can hold is known as its “capacitance”.

When a source of power is connected across both plates, there will be an electric current flow for a short time and accumulate on each plate.

A capacitor is denoted with the symbol C, with the measure of capacitance measured in “Farad”. The capacitance of a capacitor is defined as the ratio of electric charge to the potential difference (voltage) between or across the plates of the capacitor. Therefore the charge in any plate is directly proportional to the potential difference across the capacitor. This is expressed mathematically as:

Q α V
Q = CV where C = constant called capacitance
C = Q/V. for the sake of this blog been basic, I will stop here so as not to make it complex.

Below shows the symbol and diagram of a capacity:

TYPES OF CAPACITOR AND BASIC APPLICATIONS

There are basically three (4) types of capacitor namely: Ceramics capacitor, Variable air capacitor, Paper capacitor and Mica capacitor. And vacuums (open space) are use as “di-electric” pending on the intention or design for which such capacitor is meant to do. Some capacitor uses Glass, Mica, Porcelain and mineral oils as their di-electric.

A good di-electric must have the ability to return some percentage of the electric charge stored in it when the field is alternated or reversed. The parts or fractions of charge lost are known as the power factor of the di-electric:

Generally, capacitors have limits to the level or amount of charge they can hold. They can conduct direct-current for just once but they work well as conductors in a.c circuits (alternating current). This unique property makes them useful when we want to block the passage of direct-current (D.C) from entering some part of a circuit or stage in a circuit design.

Variable capacitors and fixed capacitors are occasionally use in circuits alongside with inductors (coils) as resonant circuits in radio and other electronics circuitry (electronics equipment).

Larger capacitors are also use in Power Lines to resonate the load on that line as to make it possible to generate more power.

Thanks for keeping it date again. next, i will show you how to identify and know values of capacitors. ok!

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RESISTOR

What is a Resistor?

A resistor is simply a conductor that opposes the flow of electric current to one (1 A) amperes when a voltage of (1V) one volt pass through it. Also, a resistor is an active element which can either be a carbon type or choke or wired-wound type. This component that renders a resistance to the flow of electric current plays a major role in the electronics industry today. Below is a symbol of a resistor and structural view as likely available in the markets.

The amount of resistance introduced by the resistor is what determines the amount of current flow through the conductor or circuit. This amount or level of resistance is measured by a rate of unit known as Ohms. And the standardized abbreviation in representing a resistor is R. Ohms law states that. The resistance of a resistor is dependent on the composition of material it’s made up of also known as its resistivity, also its dimension and object temperature involved. The Resistivity of a resistor is defined in terms of the ohms resistance per cubic centimeter of that substance at a temperature of 20 degree Celsius.

Applications of Resistor

A Resistor can be applied in various ways in both electronics industry and circular world at large.

-A resistor can be use as heating element in households.

In areas of cold temperature such as homes in parts of the world as Russia, Germany, and certain parts of United states, heating elements are use to keep the room temperature at a safe level needed for the body. Below shows a heating element design for homes.

- In Incandescent Lamps:

resistors are designed to produce illumination in glass tubes to provide light for visual and even around the premises for security surveillance. Below is a basic incandescent lamp

- Electronics circuitry:

where adjustment is needed to regulate the inflow of current. Certain resistors made adjustable known as rheostat or variable resistors, when adjusted they offer certain level of resistance to current flow in increasing and decreasing pattern respectively depending on the intention of the circuit designer. Variable resistor are also use in volume control in audio systems where the level of audio signal is to be regulated in amplifiers both in home-theaters, radio systems, transmitters and so on. Below shows the symbol of a variable resistor and its structural diagram.

-In Dimmer.

Certain room lighting system requires dim light (low illumination or intensity of light in the room). Variable resistors are applied to regulate or adjust the rate of flow of current in the circuit of the Dimmer thereby providing a Dull Like illumination suitable for sleeping mood at night.

Resistor Color Code

Resistors are made such as to have values of resistance in order for anyone to be able to identify and apply it independently. This is made possible by coloring. Commonly used resistors are those with four (4) colors. The last color hereby denotes its tolerance.

The color codes are arranged much that the colors seem closer to one part of the terminal than the others. Below shows a resistor and its color code written on it. The side of color closer to the terminal I indicate the start point or point to begin counting from for identification. The last color is known as the tolerance. As we humans have limit to which we can admit or accommodate things in life, so also a resistor has a limit known as tolerance to which it can withstand certain amount of current been passed through it.

The color band of the resistors and their equivalent digits are listed below:

B- Black- 0, B- Brown- 1, R- Red- 2, O- Orange- 3, Y- Yellow- 4, G- Green- 5, B- Blue- 6, V- Violet- 7, G- Gray- 8, W- White- 9,

Tolerance: Gold=±5%, Silver= ±10%. Note also that the first and second colors are the digits of the resistor value. The third color is the multiplier x10, and the fourth digit is the tolerance.

Below shows the diagram and color band on the resistor and how to calculate a certain resistor:

For instance, a resistor having colors of Red, Green, Yellow and Gold. The resistance values will be calculated as:
Red=2, Green=5, Yellow=10¬4¬¬ ¬Gold= ±5% 2 and 5 multiply by10¬4¬¬ ¬¬ ±5% 25*10¬4¬¬ ohms ±5% 250000 ohms ±5% = 250KΩ, ±5% = 12500Ω
Therefore, the total resistance becomes 250kΩ + 12500Ω = 262500Ω and 250KΩ-12500Ω= 237500Ω This means that, the resistor can tolerate between 262500Ω and 237500Ω.

These are just the few types of resistor whose resistance can be calculated using color code. There are some that their values are written directly on their body. Examples of those are Choke resistors. The picture below shows such resistor.

Other types such as potentiometer used as volume controls, their resistance value are written on their body in the form of multiplier such as 503 = 50kΩ, 104 = 100KΩ and so on.

Thanks for taking time to read through, I wish we make it a date next time as I keep you updated on basic electronics components, uses and circuits idea and applications generally.

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