Lets Learn Electronics

Make a Line Follower robot from basics

2012-08-22T00:52:00.000-07:00

As I promised in my previous tutorial, today I will show you how to make a line follower robot using the basics of our previous tutorials. But before that let’s see what a line follower robot is. A line follower robot is so called because it is meant to follow a particular path or line. The robot detects its path by distinguishing the colour of path/track from the colour of its surroundings. For example, consider the track shown below:

Now in above track, we have a simple black line. This type of track can be made by putting black tape over a white sheet or any other white background. It is not mandatory that you have to use black tape as track and white sheet as a background; I will show you how to make your robot follow any colour track.

Line follower accomplishes its task of detecting colour by using LDR (light detecting resistors) sensor. We already had a tutorial on LDR sensors where we made a simple circuit that can detect presence of light and darkness.

I recommend reading that post (click here) before proceeding because it covered fundamentals behind the working of comparator IC LM324. But if you already know what a comparator IC does, keep going.

How LDR tracks the ’track’?

Light detecting resistors are very sensitive to light. Whenever intensity of light increases, the internal resistance of the LDR decreases and current can travel through it with an ease. On the other hand when the sensor is brought into darkness, its internal resistance increases and current faces high resistance (nearly 10M ohm). Our job is to make use of this property to run the robot on desired track.

The colour black itself holds a property of absorbing light. Whenever light falls on black surface, it gets absorbed and no reflection takes place but on the other hand white colour holds a property of reflecting the light. So, whenever light falls on white surface, it gets reflected.

Now, what we are going to do is, we will use a light source such as LED to transmit light over the track and an LDR sensor placed near to LED to sense the light. As our track has two colours black and white, when light falls over black surface, light gets absorbed and no reflection occurs and when it falls on white, it gets reflected. This reflected light is sensed by the LDR sensor which in turn instructs circuit to follow the path.

Watch out how the concept actually works:

Making Brain of the Robot:

This is the most important part of any robot, its robustness, and decision making capability depends on the brain. Like human brain controls the movement of body, robot’s brain also instructs its motor when to move forward, when to take a turn and when to stop at a particular point.

Let’s see what is inside brain of line follower. The first thing we want to make robot capable of, is to detect the colour of the track, to follow a certain track, it must be capable to distinguish between two colours which in our case is black and white. This task is accomplished using LM324 comparator IC. It is capable of taking decisions by comparing two inputs. If you don’t know anythingabout LM324, click here to have a quick overview.

All we need to do is connect the LDR with the LM324 input, provide a reference voltage to the LM324 and we are done with the decision making part. I am just giving you an overview right now; I will show you how to actually connect the LDR to the comparator IC and how to set reference voltage in implementation part till then keep on reading.

The output after the comparison in LM324 is logical 1 (+5v) or logical 0 (ground). Now, to send this output to the motors, we need another IC which is 7404 NOT gate IC. NOT gate in digital electronics is simple gate which inverts the signal provided to it.

If you feed the NOT gate with logical 1 then its output will be logical 0 and vice versa. This output of the NOT gate IC is what we need to drive the robot.

Motor Driver:

Motor Driver is the part of robot which controls the motor. Motor driver is connected with the NOT gate IC, it performs following tasks:

1. Rotate the wheels in clockwise and anti-clockwise directions.

2. Apply brakes.

3. Turning off all the wheels to give motor a free wheel motion.

Motor driver IC we are going to use today is L293D H-bridge IC. L293D is used to drive small motors. It comes in a 16 pin package and is capable of driving two motors simultaneously according to the input. It is called as H-bridge IC because it has an inbuilt H like structure to control the motors as shown below:

The circuit above is an overview of H-bridge present inside the L293D. It has four switches.

1. If you turn ON switch A and switch D, the motor will rotate clockwise.

2. Turning switches C and D ON will make it rotate Anticlockwise.

3. Turing switch A and switch B will immediately stop the robot. (Brake)

4. And, if you want to try, turning ON switch B and D or switch A and C will make short circuit.

How robot takes a turn?

Yup, this question often arise because some thinks that it does not have any steering wheel or anything like that to take a turn than how the hell will robot change its direction. Well, the robot takes turn by switching motors. This switching is performed by motor driver IC. Consider we have two motors, a left motor ‘L’ and a right motor ‘R’.

1. If L and R are moving clockwise, robot will move forward.

2. If L and R are moving anti clockwise than of course robot will move backwards.

3. If L is moving clockwise and R is turned OFF then robot will take a right turn.

4. If L is turned OFF and only R is moving clockwise then robot will take a left turn.

5. If L is moving clockwise and R is moving anticlockwise, then robot can rotate 360 degree on the same place and vice versa.

So, now we know what different sections will do and what is needed, we are ready to start implementing our very first robot.

Components Required:

1. Chassis,

Our whole circuit and the battery will be placed over chassis. It comes readymade but you can also use a toy car having two motors. To do so, remove all the fancy part of toy car so that you are only left with two motors connected to wheels. Solder two wires at the terminals of wire and you are done. My own Toy car chassis is shown below:

1. Breadboard,

With complete Power supply (Click here to have a quick view on how to make a power supply)

2. Through hole PCB, Solder Iron, Solder wire.

3. Two LDR sensors,

To sense the colour of the track.

4. Resistors,

Two 10k ohm resistors for LDRs.

Two 125 ohm resistors for LEDs

5. LM324 comparator,

To take decisions over colour detected by the LDR.

6. 7404 NOT gate IC.

To invert the output signals given by LM324.

7. L293D motor driver IC.

To steer the robot.

8. A track,

Over which our robot will do stunts. Take a black tape and stick it over the white sheet. The white sheet you are using should be large enough and the tape you are sticking should not have sharp turns. Make it like one shown at the beginning of this tutorial or watch the video at the end of this post that shows my own robot.

Step 1:

The first thing we are going to do is making a sensor-LED pair. It is recommended that you use white light LED as they have high brightness. Now take you through hole PCB and solder the LDR and 10k ohm resistor and LEDs with 125 ohm resistor like circuit shown below:

Remember that LED and sensor are near to each other. The output of the LDR is taken from any of its two legs, solder a wire of around 15 centimetres (so that output can reach into potentiometer comfortably) and do the same at the other LDR-LED pair. See the actual picture of my PCB showing the connection:

Step 2:

Right now we have two wires in hand emerging out of the LDR sensors which are the output of both LDRs. Now we will compare this output with some reference voltage.

The comparison is made so as to make certain difference between the white and black colour of the track. For example, you have set some reference voltage, say 3 volts. This is fix voltage to which we will compare the output voltage of LDR.

Now, the output of the LDR depends upon the light that is falling over it. If your LDR is placed in dark then it will have large resistance across it and will allow small current (logical ‘0’) to pass through it but if placed in light, resistance will go down and maximum current can pass through it (that is logical ‘1’). So, the LDR has two outputs, either low voltage (it should be around 1.5 to 2.5v) or high voltage (4.5 to 5 volts).

Now comparison helps in distinguishing between the colours of the track. When the LDR is facing black strip of the track, it will give output of around 2 volts which is less than our fixed voltage (3 volts) and hence output of the comparator IC will be a logical ‘0’ and when the LDR face white sheet, the output of LDR will go high (5 volts) which is more than the reference voltage (3 volts) and hence output of the comparator will be logical ‘1’ (that is 5 volts).

This is how our robot differentiates between the colours.

Now insert the LM324 IC near to the corner of breadboard. Give the power supply and ground to the IC’s pin number 4 (‘+’) and pin 11 (‘-’) as shown in the picture below

Step 3:

Now to give a reference voltage, we will use potentiometer. Insert the two potentiometers near to the LM324. Take care that you insert the potentiometer correctly do not overlap its pin with the pins of LM324. See the picture below that shows how actually you have to put in the potentiometers.

The IC LM324 has four inbuilt comparators that mean you can compare four independent inputs. But right now we have two sensors, we will use two comparators and hence we are using two different potentiometers for setting reference voltage.

If you have connected the potentiometers near to the LM324, proceed to next step that shows how to interface LDR and potentiometer with comparator.

Step 4:

Before interfacing, connect the pin 1 and pin 3 of both the potentiometers with Vcc and ground respectively. Now connect the output pin (2/middle one) of potentiometer with the pin number 3 of the LM324. This is non inverting pin, which means that the input given to this pin is taken as it is while at the inverting pin (pin no. 2 of LM324) the input is first inverted (high to low or vice versa) and then taken inside.

Connect the output from the left LDR with pin number 2 of LM324 IC. Hence you can see that you have two inputs connected to the LM324. One is reference voltage at pin number 3 and another is output coming from the LDR.

We have successfully interfaced left LDR with the comparator. Now its time to interface the right LDR and potentiometer. Connect the output from the second potentiometer with pin number 5 of the comparator IC and pin number 6 with the output of right LDR.

That’s it our comparator part is complete, all we need to do is take the output of the comparison and feed it to the next IC which is 7404 IC.

Step 5:

The IC 7404, as I explained before, is meant for inversion of signals or input given to it.

Insert the 7404 IC next to comparator IC. It is good practice to keep a possible minimum distance between the two components, it will help you when you will work on PCB but before that try becoming pro in making breadboard connections.

After inserting the IC, give its pin number 7 ground and pin 14 Vcc.

Connect the output comparator output pin (pin number 1) with the pin number 1 of the IC 7404. This inverted output will be produced at pin number of inverter IC with which we will deal in next step.

Similarly connect the second comparator’s output from pin number 7 of the LM324 with pin number 9 of the 7404 inverter. If you see the internal gate structure of the NOT gate IC, you will notice there is a not gate present between pin number 8 and 9 that’s why I have taken pin number 9 of the inverter IC because it will help in reducing complexities in circuit. You can take any inverter by observing the internal figure of 7404, it has six inbuilt inverters.

Step 7:

We have completed making the brain of robot. It’s time to use this brain by connecting it to motor driver IC L293D.

Place the L293D near to the inverter IC.

Connect the chip inhibit pins i.e. pin number 1, pin number 9 and power input pin number 16 to Vcc (‘+’).

Connect pin 4, 5, 12, 13 to ground. There are more than one ground and Vcc in this IC, they are actually meant for providing ground to motors and the IC itself.

Now, check out the internal overview of L293D, you will notice, there are four inputs and outputs. We have to connect output of the inverter IC 7404 at the pins marked input i.e. pin number 2, 7, 10, 15.

But here a question arise, we have only two outputs from the 7404 IC and we need four inputs to operate motors at L293D. The answer is that for a single motor, two inputs are required. For example, say you want that left motor should start rotating as soon as you apply power to the circuit. To do so at input 1 we provide non-inverted input and at input 2, we will give an inverting input. This will make the left motor working connected at pin output 1 and output 2.

Here, the inverted input will come from the pin number two of IC 7404 and the non inverted output is taken from the pin number 1 itself.

When you finish making connection at the left motor, do the same for right input pins of motor driver.

Step 8:

It’s time to connect motor to the L293D, well it is pretty simple, insert the left motor’s wire at output pins (pin number 3 and 6) and similarly connect the right motor with output pins 11 and 14 and you are done.

The only pin left is pin number 8 of motor driver which we haven’t used till yet, well it is the input for motors. If you are using a 9 volts battery then directly connect the positive terminal of the battery to this pin. You can apply an input up to 36 volts at this pin, depending up on amount of voltage you motors can intake.

That’s it you have just now created a pretty smart robot without using any microcontroller or coding stuff. If you have any doubt on you robot that it will not work like those working on microcontroller bots, watch out my own robot in the video below:

Step 9:

The step 9 is about assembling everything you made. To do so, take you chassis, if you have one similar to my chassis then its fine, but if you don’t have one, you can take a toy car having two motors.

Now, take some tape or glue to stick the PCB at the front side of the robot. It is recommended that it should not be more than 5 cm from the ground. See the figure below showing how to fix the PCB.

Extend the wires that give Vcc to the LED and LDR, insert them into 5 volts supply of breadboard. Do the same for providing ground to them. When you will power up the circuit, the LED’s will glow and using multimeter you can check whether LDRs are working or not.

After this, fix the breadboard to chassis so that it does not move off its position when robot is working.

So, now you can put the robot over the track, connect the battery and see the robot following the track.

Convert this robot to follow White line:

To do this, insert the LDR output pin in pin number 3 that is non-inverting pin and the output of corresponding potentiometer into inverting pin (pin number 2) of the LM324 comparator. Apply same actions for second LDR’s output and its corresponding potentiometer. Your robot is now configured to follow white line.

Change the robot’s configuration to follow any colour track:

Let’s say you want to make a robot following red track over yellow background or any other light coloured background. Follow the steps below:

1. Take a small strip of red colour (or the colour your track is made up of). Turn on your robot and put the strip below the LDR.

2. Using multimeter, measure the output of the LDR, say it is 1.5 volts.

3. Now take the strip of your track’s background colour. Put it in front of LDR and measure the output of LDR, now its output will be approx 4 volts (or whatever it comes).

4. Now add the outputs in both the cases i.e.

1.5 + 4 = 5.5 volts.

Divide this by 2:

5.5/2= 2.75 volts.

Adjust the potentiometer output pin, so that output is approx 2.75 volts.

5. Take your robot to the track and BOOM it will start working over your fancy track.

Common Problems faced while making Line follower robot:

1. The LED and LDR pair is not working.

Ans: You have to provide Vcc to them, also check the polarity of the LEDs, LDR are bipolar devices.

2. My robot senses the colour occasionally.

Ans: Here the potentiometers are not adjusted, try setting its output put pin to approx 3 volts.

3. My motor driver IC gets heated up and motors moves very slowly.

Ans: Remove the Vcc supply immediately and check for the connections at L293D. Always use a multimeter to verify connections.

4. Nothing is working at all. What the FUUUU....

Ans: hehe...calm down it happens, check out if all the pins you have connected are correctly inserted in the breadboard and also sometimes IC’s pops up from their place.

5. One motor rotates in clockwise direction and other one in anti clock wise direction or The motors are not rotating in my desired direction.

Ans: Just change the polarities of motor wire at the output pins of L293D.

6. I have some other query; this whole goddamn crap is annoying me.

Ans. Yup, ask them in the comment section below and I will surely reply. You can also visit my facebook page and ask your queries there. Go to: www.facebook.com/letslearnelectronics

Okay then.... That is all for this post, in next post I will show you how to make a simple Obstacle detector robot using the same circuit of what we made today.

Till then Good Bye... :)

Wireless Communication. Setting up simple wireless communication.

2012-07-15T11:57:00.000-07:00

Note: The tutorial over wireless communication is the upgrade over my last post which was on Encoding-Decoding signals. The circuit here shows how to send the same encoded signals of that circuit without wires.Please go through my last post to learn how to make encoding decoding circuit.Click here, and if you already finished that, go on reading. Rest, alright!

What we will do:

Hey awesome guys...how are you. I am Vkas and after a small break I am ready for the next tutorial. Today I will go through the basics of wireless communication and show how to make circuit that can communicate wirelessly.

But before going ahead, I want to share a little update that took place in my life. I have joined masters program at Manipal University with Embedded systems as my specialization. I am really excited to study at one of the premier university of India...

Switching back to tutorials, wireless is the age we are living. I don’t think there is any need to describe what wireless is and what wireless devices we are using, what we are keen to know is how we ourselves can make a device that can send signals over wireless medium i.e. air.

The device we are going to make today can communicate in the range of 30 meters and the circuit is the upgrade over encoding-decoding circuit from my last post.

What it is...and How it is...:

There are two sides of communication, a Transmitter side which transmits the signal and the receiver side which receives the transmitted signal. For an instance, right now you are reading my blog. Here, I am transmitting the posts through internet on your computer screen and you are receiving these posts through your eyes and brain.

From our today’s small range circuit to NASA’s mars robots all have a transmitter (Tx) and a receiver unit (Rx).

The communication that takes place between Tx and Rx can be one way or two ways. One way communication is like your television remote. You can operate television through it but cannot do the same through the television. So, in the sense, communication is taking place in one way i.e. from remote to television.

On the other hand, two way communications can be understood by an example of mobile phone, were you can send the signal (your voice) and receive the signal (voice from another end).

In today’s post, we will learn how to do One Way communication.

The Modules:

The job of transmitting and receiving the desired signal is done through modules. In market they are available with the name – ‘RF modules 434Mhz’. The module comes in a pair and looks like the one shown below:

The word RF stands for “Radio Frequency”. The radio frequency has ability to cross obstacles plus it provides good coverage, 30 meters is actually good range when working at ground-zero level.

The RF Tx-Rx is used to transmit serial data. In simple language, you can send one signal at a time. Now let’s understand what technique it uses to make signals wireless:

Technique involved behind the scene of wireless transmission:

Before spitting the words like modulation, carrier frequency and message signals, I want to talk about Tortoise and the Crocodiles. Yes, you read it correct and I am damn serious and sure that you will understand the concept behind wireless transmission after reading this small “FACT”.

In forests of Amazon, crocodiles used to lay their eggs at the bank of river. Now, tortoises also live in same river but the fact is that tortoises are not so concern about their babies I mean they don’t take care of them after laying eggs. So, to give a small assurance to themselves that at least their babies can reach to the river and not get eaten up by birds and other animals, mamma tortoise lay her eggs in the nest of crocodiles. Now, what happens is when babies come out of the egg shells, the mamma crocodile takes babies of tortoise with her own babies to the river. Now, don’t think that why she is not eating them because according to science, mamma crocodile thinks that tortoises are also their babies. (Yup! they can eat them afterwards when she realize how stupid she was!)

Returning back to our topic, digital signals or message signals are not capable of traveling long distances in wireless medium. To take these signals to receiver a carrier is required which can deliver them to the receiver end. This carrier is called as carrier frequency which is in sinusoidal form. Now comparing this with our crocy-torty story, the baby tortoise is our message signal. Since it is not capable to reach the river of its own, mamma crocodile acts as a carrier frequency that carries the baby tortoise to the river (that is our receiver).

So, this is how transmission of digital signals takes place. Now comes another part which is different techniques of sending this modulated signal. Hey, I am not going over every technique but just for you knowledge, the digital modulation techniques are:

Amplitude Shift Keying (ASK)

Frequency Shift Keying (FSK), and

Phase Shift Keying (PSK)

The transmitter-receiver module that we are using today works on “Amplitude Shift Keying (ASK)” technique to establish wireless communication. Actually ASK is the most basic and simplest technology used to transmit signals over wireless or wired medium. Amplitude is the property of any waveform that represents the magnitude of waveform. I know this is going pretty nerd, so have a look at the animation below:

In ASK technique, a message signal and the carrier signal are blended together (modulated) and then sent through an on-off switch. As the switch is pushed that is turned ON, the modulated signal gets transmitted which is received at the receiver side as binary 1 and when the switch is released that is turned OFF, it represents a binary zero at the receiver end. Due to this On-Off technique, the ASK technique is also called as On-Off keying.

Now, as we know the technology working behind the wireless RF transmission. Let’s have a look at the modules we are going to use in our tutorial.

When observing the receiver-transmitter pair, you will notice a metal component on its surface; this part is called the oscillator. Remember, in our last tutorial I gave a brief explanation about it. This oscillator part is responsible for generating sinusoidal waves. Now, observe the receiver part, it is little bigger than the transmitter, it also have an oscillator and the IC present on its chip removes the message signal from the carrier frequency and gives out the data at Data out (D-out) pin.

The last the most important thing left is the Antenna part, i will explain it during practical implementation of circuit.

The components you will require:

1. Encoder-Decodercircuit from the previous tutorial.

2. Breadboard (one extra, for receiver circuit)

3. RF module 434MHz. (Transmitter-Receiver pair)

4. Battery 9volts.

5. Enthusiasm (important one by the way!)

If you have the circuit from previous tutorial than before making connections on breadboard, remove the wire that connects encoder-decoder data pins, Take off your entire decoder circuit (HT12D, resistors, etc.) and place it on another breadboard which will act as receiver. Now what you will have is two separate breadboards. One act as transmitter and other one as receiver.

Making Transmitter part:

Step 1.

Take the Encoder part, insert the transmitter module nearIC HT12E and connect the data out pin of the IC to the Data in pin of the transmitter. Leave the antenna pin as it is we will get back to it at last. Also provide it with proper biasing as shown in image below:

Step 2.

Completing the transmitter part, now take the decoder part that is our data decoding IC HT12D. Insert the receiver module near to it and provide it with proper biasing by connecting vcc and ground. Connect theHT12D decoder’s Data-in pin with the receiver’s Data-out pin and that’s it, our receiver part is also ready.

Leave the antenna pin for the moment. Keep all other components from the previous tutorial as it is. Do not take them out from the breadboard and we are done!

Step 3.

Now connect the circuit with the power supply. If you followed all the steps with due respect, you will see that VT pin of the decoder pin starts glowing. This pin is showing that the encoder and decoder are in coverage area and is ready to receive the data from the transmitter side. After this happens, push the reset buttons you connected at the encoder part and you will see that LED corresponding to the switch turns ON.

Step 4.

Now, while testing the circuit, take the transmitter to some distance or bring any obstacle between transmitter receiver, you will see that the LED connected at VT pin starts blinking or sometimes turns OFF. This is happening because we have not yet connected Antenna to the modules. So, let’s see how we calculate the size of antenna and connect it to the module:

Calculating length of RF Antenna:

Whether it is big antennas at radio or TV station or a small one like our circuit, the value of antenna is calculated using same method.

Wavelength of antenna is equal to the ratio of frequency on which our device is working and the speed of light. Therefore:

λ = f/c

λ = 434000000/300000000

So, λ = 1.44 meters

To have best range, the antenna should be one-fourth of the antenna size. Such that:

Size of antenna = λ/4

Hence, 1.44/4=0.36 meters or 36 cm.

Therefore size of antenna should be 36 cm.

So, now we know the length of antenna, we will now make one, well it is very simple. Take a 36 cm long single core wire (same wire you are using in breadboard connection) and insert it in the antenna pin of transmitter. Do the same with another antenna of 36 cm at the receiver end.

Test the circuit by taking transmitter at some distance. You will notice enhanced connectivity and your circuit will become capable of crossing any obstacle in between.

So, from today’s post, we saw a very basic wireless circuit. We will go advance in coming up tutorials when I will show you how to make a wireless robot.

Yep, circuit diagram, the moral of the story is shown below:

Transmitter Circuit:

Receiver Circuit:

That’s it for today, hope you got what I wanted to explain. If you have any query in any part or my other tutorials, just post it in comments below.

If you find my tutorials helpful, do share this with other. To read more interesting tutorials and more.. Join me at:

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Thank you for the read,

Have a nice day..

Introduction to Encoding and Decoding. Making a simple Encoder-Decoder device

2012-07-05T10:07:00.000-07:00

Hey guys how are you, I am vkas and in our today’s post I will introduce you with the concept of Encoding and Decoding and will show how to encode data at one end and decode it at another end. I will also go through the concept behind address lines in electronics actually means.

In today's post I have made some animated content in flash for better understanding, in case if your connection is very slow, then may take a moment to load. If you face any bug in them please post about it in comment box below. Yup, rest alright as always..let's start..

What is Encoding and Decoding:

In simple words, encoding is wrapping up the data. The data could be anything like simple binary data (in the form of 1's and 0's) or it could be an audio signal or it could be certain text. But here we are dealing with the encoding that is used for binary signals. The wrapped data is called as a Packet. This packet is sent through a medium (“Through wire or wireless”) to the decoder part where it gets unwrapped or decoded. Yes, now what you are thinking is right, it is exactly similar to posting an envelope. Encoding is when you put the letter into envelope, the postman is medium to take the envelope to the recipient and when recipient opens the envelope then it is called decoding.

So, essentially to apply encoding and decoding technique in our digital world we need three entities: (1). A sender or in electronics sense it is Transmitter. (2). To receive this sent data we need a receiver. (3). and of course we need an address of the receiver. The role of address in electronics is played by address lines.

HT12D and HT12E

In today’s episode, I am taking an Encoder-decoder IC pair. In market, it is available with the name as HT12E and HT12D. The ‘12’ in the name means 8-address lines and 4-data lines while E and D letters represents ‘Encoder and decoder’ respectively.

HT12E(Transmitter side)

Let’s first take the Encoding side. The encoder has four input lines. Theses lines are used to give input which we want to encode. In encoding, we are wrapping up the data which means if we want to send a binary signal ‘1001’ to other end, we have to make data pins as ‘1001’. Now, to make data pin like this, what we need to do is to give high or 5 volts (which in digital means ‘1’) to pins ‘D0’ and ‘D3’ while we have to provide pins ‘D1’ and ‘D2’ with 0 volt. (Ground). This altogether gives us ‘1001’ which is transmitted out from the ‘Data out’ pin of the HT12E. The input given to data pin is in parallel form which is being transmitted into serial form from the data output pin. The figure below will clear this:

Our data is now been encoded and will be transmitted. The transmission medium could be anything, it could be our regular wire, or wireless. In this tutorial, we are going to use our steady single core wire which we use to provide connections in breadboard (nothing fancy!).

The data flows in serial form through the wire and reaches the other end i.e. to the receiver. Receiver now decodes this signal. So, let’s see how decoder works:

HT12D (Receiver side):

Below is the pin diagram of HT12D decoder IC.

Now neglect all the pins for this moment and just concentrate on Din (Data in) pin and the for Data lines pin. The encoded data which is coming from the transmitter side goes into the Data in (Din) pin. The data which was in serial order gets decoded and the output is generated at the for data line pins in same order as that on transmitter pin.

Yup also remember: When there is no input at the data in pin, the output pins i.e. data lines remains high.

The figure below shows the decoding taking place in HT12D

Role of Address Lines:

When using a single pair of encoder-decoder IC, we generally leave the address pins as it is i.e. we do not connect them to either ground or VCC. But what if there is more than one decoder but only single encoder. In that case we need to give an address to the data that it might travel to specific decoder only and our data should not leak at unnecessary decoders. This is very useful in wireless communication.

To define an address, what we need to do is to connect specific address pins to the ground on both encoder and decoder side; remember that the order of connecting the address pins to the ground must be same. See the animation below for; it will remove all the twists in your mind:

Oscillator Pins:

When we first hear the word oscillations, the first thing that comes in our mind is the to and fro waving motion, yup as always you are correct. The role of oscillator in digital electronics is to produce waves which are in Sine wave form or rectangular wave form. The device used to generate this waveform is called ‘Oscillator’. The waveform generated by the oscillator is called as ‘Pulses’ (like our heart beat). So, in digital world the oscillator works identical to our Heart. Unfortunately, we will not be able to see the oscillator device itself because in HT12D and HT12E, the oscillator comes inbuilt, what we have to do is to put a resistor between the oscillators pins. But, in our coming tutorial over microcontrollers, the need of oscillator is must, so we will learn about it in that tutorials only.

VT Pin (Valid Transmission):

The valid transmission pin in decoder shows that the transmitter address and the receiver address are same and is ready to receive the data from the encoder side.

During implementation of the circuit, we will see how to get notification about the valid transmission through this pin.

So, now we are loaded with all the essentials needed to implement Encoder-Decoder circuit. Let’s start implementing one:

Components Required:

1. IC- HT12E/HT12D (generally comes in pair).

2. Breadboard with complete Power supply.

3. LEDs (5)

4. Resistors (Four 125 ohm for LEDs)

(750k ohm for oscillator of Encoder)

(27k ohm for oscillator of Decoder).

5. Reset Switch (4).

6. Battery (6-24 volts)

7. Like always....your enthusiasm...

Step1.

Take the power supply circuit and insert the encoder and decoder IC’s at some distance. Also provide the VCC and ground to the pins (Pin number 9 ground and pin number 18 VCC for both the IC’s). See the figure below:

Step2.

Now, we will first make the encoder part. Insert the 750k ohm resistor in pin number 15 and 16 i.e. you have to short both the pins using this resistor. Connect the ‘Transmission Enable pin’ (TE) to ground. This action will enable the IC to transmit the data through data out pin. Now connect four reset switches in data line. Remember, reset switch has two legs. One will go into the data line and the other one will go to ground. So, whenever you will press the switch, the pin will get connected to the ground. See the figure below which how actually you have to connect the switches:

Step3.

Yup, our encoder part is completed. You are ready to encode your secret data. But there should be something which shows the reception of data at data output lines. We are using LEDs for that purpose. The LED will glow when data is received. So, let’s put down hands over decoder circuit.

Connect all for LEDs separately with the four data lines of decoder IC. To have a better understanding, I am not showing the 125 ohm resistor. If you don’t know how to connect resistor or having doubt over polarity, then click here to have quick tutorial.

Also connect or short pin number 15 and 16 with 27k ohm resistor.

Step4.

That’s it, we are almost done. Now connect our last LED at the VT pin of the decoder. When circuit is given power, the LED at VT pin glows, it gives the indication that decoder address is matched with the encoder and ready to have Valid Transmission. At last connect the data out and data in of encoder and decoder respectively. The circuit will work in the same way as shown in the window below.

Click the button D0, D1, D2, or D3 at the encoder circuit to view the working of our encoding and decoding circuit.

The complete circuit on breadboard will look like this. The bold blue line in centre of the breadboard connects the data in and data out pins. You can also do this with real breadboard by taking the wire through the slot provided in centre of breadboard. This makes the circuit look less messy:

And this is how my own circuit looks (I am using single data line and two breadboards for ‘Impression!’ J ) My finger is pressing the switch at encoder part.

The Moral of the story i.e. circuit diagram is shown below:

Now, whatever switch you are gonna press, exactly the same will turn on at the decoder part. This circuit have great importance when working with wireless RF device which I will surely cover in upcoming tutorials.

If you have any sort of doubt in this tutorial or any other of my tutorials, feel free to comment below, i will surely reply. You can also send me mail at letslearnelectronics@gmail.com

Hope you got the basics of encoding and decoding techniques. In next post I will show you how to convert ‘0’ to ‘1’ and vice versa also we will have a look over different gate IC’s like AND gate IC etc. Till then.....

Have an electrifying day..

Playing with Sensors. Making a decision taking device.

2012-06-24T19:37:00.000-07:00

Sense is what makes humans different from machines and other animal. But to sense, we need a sensor which in our case is our nose, ears, tongue etc. We can sense happiness, guilt, love, anger, suffocation, wind, cold, hot, taste, smell, surroundings and much more. Similarly, in electronics, numerous numbers of sensors are present but these sensors are mostly meant for getting a feel of physical nature like sensing rise in temperature, light, humidity, obstacles, gas etc. These sensors plays an important role in electronics, they makes the system more intelligent as it has an ability to make decisions on its own.

In any circuit whatsoever it is, if it has a sensor in it, it follows the same steps as shown in above blocks. Let me explain this diagram:

Every sensor has its own property. Like:

“Light detecting Diode” (LDR) senses light.

“Temperature Sensor” (like LM35) senses temperature.

“Infrared sensor” (IrDA) senses obstacles.

“Tilt sensor” senses the movement (like mobile phone’s accelerator)

“Humidity sensor” senses humidity in air.

And so on….

To know about how sensor senses the environment, consider an example of light sensor (LDR). They are used to sense the light and dark. The resistance of the LDR in dark is very high which sometimes up to 1M ohms. But when light falls over its surface, the resistance decreases drastically and conduction through it takes place. In our today’s tutorial, we are going to take decisions on the output of sensors. But to make one let’s take an overview of decision making IC, we are going to use in our circuit.

Op-amp IC:

First of all let’s see how an op-am IC actually looks like. In my case I am using LM324 which is shown below:

The IC package has 14 pins Dual in-line package. This means that the pins are located in two parallel rows. The counting of the IC pins is done from left of the notch. The IC LM324 has four independent operational amplifiers. An operational amplifier looks like the one below:

So, inside the IC package, it looks like this:

Now, we know how it looks like let’s see how it works like.

The comparator here has two input values, Input (+) and input (-). These positive and negative inputs are called as non-inverting and inverting inputs respectively. Now, in digital world, the input voltage what we are providing to the circuit i.e. +5volts is called as ‘1’ (one) and the ground terminal is called as ‘0’ (zero). These one’s and zero’s are all that you computer or the digital electronics understand. So, in our Op-amp IC, the inverting terminal means that when input of +5 volt is applied at that terminal, it is first inverted that is, it is converted to Zero and then taken as input while at the non-inverting end, the +5volt is taken as it is and no inversion is done. But why this inversion is done? We will see this when we will make our decision making circuit. Now, in op-amp at any of the input (of same op-amp, say input 1 +), a reference voltage is provided. Reference voltage means a constant voltage through resistor is provided and at the other input (input 1 - ), the voltage to be compared is given. Whenever the input 1- exceeds the reference voltage, an output is produced at the output pin.

If you didn’t get the technical comparison process of Op-amp, let’s compare it with our day to day example: Op-amp is like fruit vendor’s weight scale. If you are buying apples say 1kg, the vendor will put 1kg weight on one side, this is the reference weight identical to the reference voltage in our Op-amp case. Now he starts putting apples on the other side of the scale. When the weight exceeds the reference weight, the scale will get down on the heavier side and if it is less than 1kg, it will remain at the side of reference weight. So now I consider myself that you got the idea behind op-amp IC’s.

So, the idea behind using an Op-amp as a decision making circuit is very clear, if the input to its pin crosses the predefined reference voltage, it will give the output and if it does not crosses it, the output will remain idle.

In our today’s circuit, as I promised in my last tutorial, we are going to make a literally useful cum fun circuit which will light up in dark and turns off automatically when in light.

The components we need are:

1. Breadboard with power supply (click here to have tutorial on making power supply)

2. IC LM324

3. LDR sensor (To detect light)

4. Resistor (10k, 125 ohms).

5. Potentiometer (10k) (What is this potentiometer?? We will discuss while implementing it).

6. LED (5mm)

7. Yup…like always…your enthusiasm.

If you got all this things let’s start making it.

Step 1.

Take your power supply and insert the IC LM324 in the breadboard as shown below. Remember that you insert the IC pins in a manner such that they does not short each other. See the image below:

Step 2.

Now connect pin number 4 to VCC and pin number 11 to ground. This step is also called as Biasing of the IC. So, provide proper biasing to the circuit and check the connections using multimeter:

Step 3.

After applying the biasing, insert the LDR near to the LM324 pin number 1. We are taking first Op-amp for this circuit. Now LDR doesn’t work on direct 5 volt supply. We need a resistor to have proper biasing. Connect the 10k ohm resistor in any of its pin (as it is a Bipolar device, means it does not depends on polarity, conducts in both directions like simple resistor). Take the resistor’s pin into VCC, connect the second pin of LDR with ground using single core wire.

Step 4.

Now, we need an output from the LDR which will go to the LM324’s comparison input. The output can be taken from any of the two pins of LDR, in our case, lets connect the ground pin of LDR to any of the two inputs of Op-amp in our LM324 IC which is pin number 2 or pin number three. I am connecting it to input 1(-) i.e. pin number 2 of LM324….I know it looks lame sometimes that I am saying connect the wire here and there without explaining but keep patience and believe me…the line where this post will end , your doubts will be cleared!!

Step 5.

That’s it, our LDR interfacing is completed. Now it’s time to introduce potentiometer to the circuit and to you. Potentiometer is a three terminal (3 pin) device which acts as a variable resistor. That means it can vary the value of resistance. The difference between our simple resistors and potentiometer is that a simple resistors have fix value of resistance for example resistor carrying 10k ohm of resistance value cannot be varied to 1k ohm but a potentiometer having value of 10k ohm can be varied right from zero ohms to 10 k ohms by rotating the screw over its head:

As from the above figure, the output resistance is the one we need to connect with the pin number 3 of Op-amp as a reference voltage. Right now don’t worry about varying the resistance or about the value of reference voltage. Just connect it to the pin number 2 of potentiometer with the pin number 3 i.e. input (+) of the Op-amp. See the figure below to have a quick idea.

Step 6.

As now our reference voltage and sensor are done, it’s time to insert LED in the circuit which will respond to the decisions taken by the LM324. Insert LED anywhere or preferably closer to LM324. Connect its positive leg to the pin number one of the LM324 which is the output of our Op-amp via resistor of 125 ohm. Connect another leg to the ground and we are all set to go. Our circuit is complete now and ready to make decisions.

But before our circuit works, we have to set a reference voltage using the potentiometer. To do so, check out the steps below:

Step 1:

Connect the circuit to the power supply/battery.

Step 2:

Take out your multimeter and insert its ground strobe inside the IC7805’s hole present in its metal heat sink (it is connected to ground). Now touch the positive strobe of multimeter with the pin number 2 of LM324. You will notice certain voltage on the multimeter screen. Now keeping the red strobe at the pin number 2, hover your hand over the LDR sensor. You will surely notice a drastic change in the value of voltage. If previously it was 3 volts, it will show 5 volts. This verifies that our sensor is working fine.

Step 3:

Now it’s time to set the reference voltage. So, to accomplish that, touch the positive strobe of multimeter with the pin number 3 of the LM324. You will see some voltage at this pin ranging between 0 to 5 volts. You have to set the value of voltage which is just above the output voltage of sensor in idle state i.e. in light. Say if your sensor output voltage was 3 volts in presence of light, you have to provide a reference voltage of 4 volts. So when you take the circuit in dark, the sensor output will exceed reference voltage and output of Op-amp will go high and our LED will light up.

The second case:

If your LED lights up as soon as you provide power to the circuit, then to overcome this problem, just interchange the connections at pin 2 and pin 3 of LM324. This can explain the phenomenon behind inverting and non-inverting input voltage. The sensor gives out zero as output when it senses the absence of light. The inverting port inverts it to some positive value voltage and then compares it to the second input which is non-inverting in nature. But if you connect the sensor output to the non-inverting pin, then the circuit will turn off when in dark and lights up when in light.

So, from today’s tutorial, I hope you got an idea how about simple decision making device. Identical circuits are being employed in street lights to have automatic switching. This decision making device is also used in making “Line follower robots” which I will cover after few tutorials. Similarly, if you run the horses of imagination and creativity, you can probably make many devices.

I hope you liked my today’s post. If you have any sort of query regarding the making of circuit or any other questions on electronics/digital electronics. Please post a comment below or you can send me mail at: letslearnelectronics@gmail.com.

Thank you, see you in next tutorial. Have a nice day.....:)

Calculating the value of resistor and testing a simple LED circuit

2012-06-20T12:23:00.000-07:00

You often got encountered with circuits having many resistors of different colors. We also often think that how a circuit designer comes to know what value of resistor is to be connected with the particular component like LED, IC or in any other biasing circuit. We are going to resolve this today.

In earlier times, there was a scientist named Georg Ohm who blessed electronics by giving a law known as (well you know that!!) Ohm’s Law. According to which “A resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force.” Yes this looks to be a bit confusing but the moral of the story what Georg wants to let us know can be simplified by its mathematical formula:

R=V/I

Where R= Resistance

V= Voltage

I= current

Resistance is the property of any conductor which opposes the flow of current through it. The element that posses this property is called as Resistor but every element like a good conductor such as copper also possess very small amount of resistance. The opposition or “Friction” provided by these elements to the flow of current is dissipated in the form of heat. This is one of the many reasons behind heating up of electronic devices.

Why we need resistors when we got a power supply of 5 volts:

In previous tutorial, we made power supply that delivers us a voltage of 5V (volts). This voltage level is comfortable when working with IC’s but for LED’s, this value is very high. To lower the input voltage supply to the LED, we will give some resistance to the flow of current using resistor.

Calculating the resistor value for LED:

To calculate resistor value, we need to know about two things about LED, its input current and the voltage on which it is working on. The general purpose LED’s comes with a rating of 2.5 volts and 20mA (Milli-amperes). So to calculate the resistance, follow the steps below:

1. Determine what value of voltage you are providing to the circuit. In our case, it is 5 volts.

2. Now find out what is the value of voltage your LED is seeking for. In our case, it is 2.5 volts.

3. Now subtract the voltage required by the LED from the Input voltage .i.e. 5v-2.5v= 2.5 volts.

4. Now divide this voltage by the current value which in our case is 0.020 Amperes (Ohm's law).

R=V/I

R= 2.5/0.020

Therefore, R= 125 ohms

So, we have to use a resistor of rating 125 ohm to light up the LED. Now when you will go to market to buy a resistor of this rating, you will never find out one having exact rating, well nothing to worry about, you can always use a resistor which have ratings close to that we calculated.

Also, if you want to directly light up the LED with your battery i.e. without making a power supply unit, Then in that case, if you battery is of 9 volts then use resistor of value ranging between 325 ohms to 470 ohms.

Positive and negative lead in LED (Polarity):

Sometimes or I must prefer saying mostly beginners use to detect the poles of LED by checking the length of its leads or legs. In general, the longer leg is positive and the shorter one is negative leg. But what if both the legs have same length?

Well to find the correct polarity, take a closer look at the LED. You will see something identical to pic below :

The LED has a semiconductor chip, which in this case is wider part. This is the positive lead of LED and the other lead connected to less wider part is called as lead frame. It acts as negative polarity of the LED. Hence, now you can find out the polarity of LED with an ease.

To have a quick check of polarities in LED, set your multimeter on diode mode. Now touch the positive strobe of multimeter to positive leg (Anode) of LED and negative strobe of multimeter with the negative leg (cathode) of LED. You will see that LED started glowing.

We now have a resistor of appropriate value, a power supply unit and that’s all we need in our circuit to implement. Let’s start making one.

Components you will need:

1. LED.

2. Resistor. (We have calculated the value of resistance for 5 volts and 9 volts. If you are using Battery/voltage source of any other voltage rating, calculate the same by following above steps.)

3. Potentiometer (It is explained in implementation part.)

4. Voltage source/battery (more than 5 volts).

5. Our power supply unit from previous post.

6. And one more thing from last post Enthusiasm…!

So, here we go:

Step 1).

Take the power supply unit that we made in our previous tutorial. (If this is the first time you are reading my blog click here take a tutorial over making a power supply).

Step 2).

Now insert the LED in the component bus as shown in the pic below.

As our component bus is connected vertically from inside, in case if you don’t know about breadboard inside, click here.

From above our circuit will appear somewhat like the one below:

Step 3).

Now it’s time for resistor. Insert the resistor of value you have calculated from above steps and insert one of the legs of resistor in the same vertical component bus in which you inserted your LED pins. You can insert the resistor in either of the pins that doesn’t matter. Now insert another leg of resistor in the source bus. Take care of polarity of LED. But remember, either way you do, current should first cross the resistor and then enter the LED. Connect the left LED pin to source bus by a single core wire as shown below:

Step 4).

Okay… the circuit is completed. Insert positive of battery in the pin number one of IC 7805 and negative in the pin number 2 of IC 7805 and BAM! Our LED will start glowing.

Watch the video showing the step by step implementation of above circuit below:

So, this was the easiest circuit built on the breadboard. From now, I hope you have become pro in breadboard connections. If not, read my previous blog and do little work out on it. Therefore, considering this I will not repeat the breadboard connections in the upcoming tutorials because sometimes we get irritated by reading something which we already know.

I know you didn’t get the feel of electronics till yet. But in the next tutorial, I will introduce you to the sensor called LDR and will make a fun circuit which lights up LED in dark automatically and turn it off in presence of light. We will also take a closer look on integrated circuit called as Op-am. So keep reading and keep learning.

Thank you for the read. Have a nice day….

Setting up power supply and using a multimeter:

2012-06-14T15:12:00.000-07:00

Now after having an overview of breadboard let’s move forward to next step that is making a power supply on the board. Before starting let me tell you what is a power supply and why it is “a must to have” part of any circuit.

Power Supply:

If you are familiar with the hardware of computer you probably had heard about its one of the many sections called as “Power supply”. Well if you are not familiar with it, it’s not a big deal. Every electronic gadget that you come across in your day to day life like mobile phones or computers or washing machine or television or any other gadget, they all consist of power supply unit. But here a question arises that “Why the heck we need a power supply?? Can’t we just start making some cool stuff directly?” The answer to this question is simple, we know that all electronic circuits work on some power or electricity (Obviously we know that!). Now the circuits and projects we are going to make in upcoming blogs takes up 5v (volts). The supply is DC (Direct Current) in nature and the battery we are going to use is of 9 volts or may be more that means our circuit will either get ruined up or will not work according to our expectations (Yes this happens when dealing with IC’s etc). So the work or use of power supply unit is to convert this high voltage to the level, our circuit loves to work with.

Our power supply unit will have two main units an IC 7805 and capacitors. And why they are important in our circuit, read on…

7805 voltage regulator IC:

7805 integrated circuit is meant for converting a high input voltage to 5 volt output. The IC works in the range of 5 volts to 24 volts. As I explained before that we are going to use voltage source higher than that of circuit requirement, so in order to have voltage level of 5 volts we are using 7805 IC. The last two digits of his IC i.e. ‘05’ indicate the value of output voltage. The pin diagram is shown below.

To count the legs, hold the IC such that its metal part is facing towards you. Now simply count from right to left. The pin at extreme right is pin number 1 input voltage supply i.e. our battery’s positive terminal will go here which can be of any value from 5 volts to 24 volts. The middle pin is the ground pin. The negative terminal of the battery or voltage source goes here and the left most pin i.e. pin number 3 is the output voltage which is 5 volt. These 5 volts are the needed voltage for our circuit and we will supply it throughout the breadboard

Capacitor:

Components like IC’s etc create noise while working, well this is not noise in the form of sound but in the form of spikes that are created in a dc current.

These spikes seriously ruin the circuit. Moreover, when these spikes are generated by components, the power supplying unit is not able to adjust itself according to the brief period of change in voltage due to spikes. Hence to overcome this effect, a simple dielectric capacitor is used. The capacitors are capable of storing charge. They act as local energy storage in the circuit. These capacitors in a way, protects power supply from the circuit’s noise, they decouple both of them and hence these capacitors are also called as “Decoupling capacitors” These capacitors are capable to respond the instantaneous change in current. Hence they play a vital part in power supply unit.

For an instance you have came across the effect of decoupling capacitors. When you turn off your computer or television, you can see that after being plugged-off, the monitor takes time to turn off may be few seconds. This is the effect of capacitor. The time delay is due to the stored energy in capacitor and it takes time to discharge. As the capacitors get discharged, monitor turns off.

We will not be able to see this effect in our circuit because capacitor we are going to employ will have values in few micro farads they are capable of storing small charges as our power or voltage source is also small.

So, this was all about the theory part of power supply. Let’s begin making one.

Components you will require in making power supply are:

1. IC 7805.

2. Capacitor 10uF electrolytic type.

3. Single core wire.

4. Multimeter

5. Battery/Power supply (must be 6 volts or up to 24 volts.)

6. Wire stripper

7. Enthusiasm/Will Power (well this is most important one!!)

I have linked some of the components to the Radio Shack if n your locals. (Except 8^th one…J )

If you are ready with you components, let’s start making it step by step:

Step 1)

Connect both source buses to each other so that our supply current can flow throughout the board. Remember that breadboard’s source buses are divided into two halves. There are ten blocks of buses. Among them first half i.e. five blocks of buses are connected to each other and then second half having rest five blocks are connected to each other. Refer to the figure below to clean up the mess. Click here to know more on breadboard basics. We need to connect both these halves as shown in figure below.

Step 2):

Now connect 7805 IC just like it is shown below. For the ease of understanding we are connecting it to the extreme left of the breadboard. After becoming a pro in breadboard connections you can connect the IC anywhere you want in the circuit. The IC is connected in our “component bus”. Now our IC has settled down. It’s time to connect to the source bus with 7805. Well it is very simple. As I told you before, we want to flow 5 volt in our circuit and we also know that pin number three of IC 7805 gives out 5 volts. So we need to connect this pin number three with the source bus.

The source bus has two lines of holes. As you can see in above photo, the 5 volt output pin is connected to the lower line of source bus and the ground of IC 7805 is connected to the top line of source bus. The top bus is grounded so now it is termed as “Ground or gnd” and the lower one is connected to +5 volt supply so it is called as “VCC”.

Step 3):

This step is similar to step 2. All you need to do is connecting the output and ground pin to the other half of the bread board as shown below. Now take out the multimeter and check out if connections are alright. To do so, cut out a small single core wire and insert it to the right most hole. Say you have connected it in VCC. Set the multimeter to diode mode. In this mode whenever the strobes of multimeter are touched together or to some conducting surface, a beep sound is produced. So, connect or touch one of the strobe of multimeter with the wire you have just connected temporarily at right most hole and touch the other strobe to the pin number three of the IC7805, if you hear a beep sound, your connections are alright and if not, then keep patience and check the connections again. In similar manner check for ground bus connection. Pull out the wire you just inserted in VCC and plug it into the ground bus and again check the connections by touching the strobes to the wire and the middle pin of 7805 IC.

Do not forget to check the connections at both the source buses and for both VCC and gnd. This check through is very important and if not taken care off can result in messing up of whole circuit. The upcoming tutorials will have some seriously simple yet complex looking circuits and this check through will help you complete your circuit in single shot. (As it is very irritating when you discover that your circuit has some error…well computer programmers can understand this feelings…doesn’t matter how patience you have!).

Step 4):

Now comes the capacitor part. It is also very simple just connect the capacitors in both the source buses. Remember that capacitor is electrolytic in nature so pay careful attention towards the polarity of capacitors. To locate positive and negative terminals of capacitor, examine the capacitor’s body. You will see a thin strip stating ‘-’ (minus) sign. The lead below this strip is negative and of course another one is positive. Insert positive of electrolyte in VCC line and negative terminal in the ground line.

Refer to the photo below showing the implementation of capacitors.

Step 5):

That’s it, your power supply is now ready. It’s time to check out whether our board has 5 volts throughout the board or not. Connect the battery’s positive terminal to pin number 1 of the IC7805 and its negative terminal to the pin number 2 i.e. ground pin of 7805. This will initialize your IC and a steady output voltage of 5 volt is provided at pin number 3. Let’s verify this, to do so, set your multimeter to ’20 volts’. Now touch the negative strobe (mostly black one) to the middle pin i.e. ground terminal of IC7805 and positive terminal to the right most hole of the source bus as shown below. You will find the reading between 4.8 to 5.2 volts.

Watch out the video to have a clear view:

So, our power supply is verified and working like a charm. If not, read this post again. Most of the times people make mistake in counting the pins in IC 7805. Always count the pins from right to left with its metal part facing towards you.

In the next blog we will go through a simple circuit of lighting up LED’s. Right now you will be finding all this little boring but these are very essential to clear the basics of electronics. Stay tuned to my blog and feel free to send me mail at letslearnelectronics@gmail.com or post a comment below if you have any query about the topic or electronics.

Thanks for the read. Have a nice day... :)

Introduction to Breadboard

2012-05-31T11:43:00.001-07:00

This is my first post to blogger....so anyone not getting what I am trying to explain or any issues in understanding the blog, feel free to send me an email at letslearnelectronics@gmail.com.
Lets begin..

What is Breadboard:
A Breadboard or a Protoboard or Plug-board is a testing board used for testing of circuits before implementing them permanently on PCB. It is a simple plastic board which is wired from inside in a particular manner and you can test circuit comprising of IC's, resistors, capacitors and many other pin devices by just plugging it inside the holes provided. Breadboard are reusable, you can do as many implementations as you want. For those who never saw a breadboard before than check out the image below..

If you are not able to find this at your local store selling electronic component, order it online from radio shack.
Here is the link

Now if you got one and ready to start than go on reading..

Whats inside a Breadboard:

A Breadboard has three sections. The top most section and the bottom most section are same and we will call it as "Source Bus". Our power supply through out the breadboard will be through these buses that's why they are termed as source bus. The middle section is were we are going to make all our connections like interfacing of circuits, microcontrollers and other IC's and all that stuff. So these buses are meant for components connections so we will call it as "Component Buses".

The image above is the interior look of breadboard. The buses are simple metal strips having a holding mechanism. Whenever you insert any component (resistor, IC, capacitor etc) in it, the holding mechanism grabs the leads of component and the bus get connected to the component. Another thing about breadboard is that if your circuit takes up very large space, then you can also join two breadboards together by inserting the slots into each other provided on the border of the board. So these are all the basics about breadboard

Now, in the next post we will go through making power supply on the board and will have a quick look at a simple circuit implementation. Also keep tuned to my blogs to discover more about electronics. Remember to comment or send me an email for any query at letslearnelectronics@gmail.com.
Thanks for the read and your interest in reading. Have a nice day... :)