Simple Robotic Arm Project Using Arduino

Robotic Arm Project Using Arduino Nowadays, manual labor is being reduced at big scale industries and factories to increase efficiency and gain profit by installing robots that can do repetitive works. A onetime installation of such a device may cost a huge amount, but in the long run, will turn out to be more profitable that manual labor. Out of the lot, a simple robotic arm is one of the most commonly installed machines. We are introducing the basic concepts of an Arduino controlled robotic arm project. The programmable robotic arm finds extensive applications in its use in extreme conditions like space mission or underwater expeditions. It is also using in nuclear power plants and in toxic atmosphere where human surveillance is difficult. There are numerous types of robotic arm used in industries but going to give you details on a basic prototype. The movement of parts is done by servomotor, which can rotate approximately up to 190 degrees. The whole circuit is powered by 12-volt adapter and an Arduino Nano is used as the controlling unit. The servo motor for robotic arm is controlled by android mobile. The communication between mobile phone and servo robot arm is done by Bluetooth module HC-05. Components Used Arduino Robotic Arm Project – Working The mini-robot arm uses four servomotors to move the arm. Servomotors are controlled by Arduino and connected to the PWM pin of Arduino. There are eight buttons in the android app. Out of these, four buttons are used to control the four servo motors. One button is used for clockwise rotation and other is used for anticlockwise of the mini robot arm. The Bluetooth app interface is shown in the figure below.   Out of eight buttons, four buttons are Red and four are Yellow. When a button is pressed it sends a unique character to Arduino via Bluetooth. As soon as the Arduino receives the character, its command is identified and rotates the servo motor accordingly. For clockwise rotation of servo motor the red button in the application is to be pressed. Four buttons are used for each servomotor. When the red button is pressed it sends two types of characters. First is the press character and the second is the release character. When a button is pressed, a character is sent through Bluetooth and the Arduino rotates the servo motor one degree in one cycle. If button is not released servomotor moves one degree in next cycle. This same process is also used when yellow buttons are pressed, but this time the servo motor rotates one degree in the anticlockwise direction. Press and release characters are shown in the table given below. Programmable Robot Arm – Press and Release Characters Arduino Robotic Arm Project – Circuit In the circuit, Arduino Nano is used and Bluetooth module HC-05 is connected to it. Servomotors are connected to PWM pins of Arduino and the circuit is powered with 12 volt DC adapter. There are three pins in the servo motor. One is the Vcc, other is the GND, and the third is the SIG pin. The SIG pin is connected to PWM pins of Arduino. The pins 6, 9, 10 and 11 are connected to the servomotor. Bluetooth module has four connecting pins. Two of them are Vcc and GND. The other two are Rx and Tx pins. Rx pin is connected to pin 8 of Arduino and TX pin is connected to pin 12 of Arduino. In the robotic arm project using Arduino, an etched PCB is used. The PCB design is given below.   The circuit diagram is given...
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Anti-inspiration

Are you’re waiting for inspiration to learn electronics?

Here’s some anti-inspiration.

I read this quote a few weeks back, but I totally forgot who wrote it.

And I don’t remember the exact words.

But I remember the message. It was:

“I don’t believe in inspiration. Inspiration is for amateurs. The rest of us just sit down and do the work.”

Also, in the gym I’m currently at, there’s a similar quote by Michael Jordan:

“I’ve always believed that if you put in the work, the results will follow”

Those two really resonated with me today.

Are you putting in the work?

There are many ways to “put in the work”.

One is by building the circuits in 9 Circuits:
http://ift.tt/2rkHzJS

Keep On Soldering!
Oyvind @ build-electronic-circuits.com

Copyright Build Electronic Circuits

Flexible new platform for high-performance electronics

A team of engineers has created the most functional flexible transistor in the world -- and with it, a fast, simple and inexpensive fabrication process that's easily scalable to the commercial level. It's an advance that could open the door to an increasingly interconnected world, enabling manufacturers to add 'smart,' wireless capabilities to any number of large or small products or objects -- like wearable sensors and computers for people and animals -- that curve, bend, stretch and move.

Band gaps, made to order

Engineers have created atomically thin superlattice materials with precision.

Biodegradable microsensors for food monitoring

A new generation of microsensors could provide the vital link between food products and the Internet of Things. Researchers have developed an ultra-thin temperature sensor that is both biocompatible and biodegradable.

DIY – GSM Relay Control Using Smart Switch Board

The main objective of this project is to control the ON/OFF status of electrical appliances at home or company remotely using a cell phone and relay switch. The appliances may include lights, fans, pump, and air conditioners and so on. Though all the household items can be automated to change their ON/OFF status, our prototype model GSM remote control circuit uses 8 electrical appliances. The project includes multiple users to control the appliances and uses unique SMS formats for each application. The switch board can be operated by SMS feature of the mobile phones to ON/OFF the electrical appliances in home or office etc.., only by the registered users. The system validates the users and also the message sent by the user. The list of options served by the system is given below. Get ON/OFF status of the Loads Get Users List Add an User Remove an User Get Account Balance of the SIM Reset Message Counter GSM Relay Control Board – Circuit Diagram Features of the Smart Switch Board  What happens if an unregistered user operates? If an unregistered user tries to operate, the system replies a template “Unregistered User. Please contact admin.” The system also sends an SMS to the first user in the users list or the programmed user (if no user is added) a template “Tried to operate the switch board.” and the contact number of that user. Below is the real-time simulation output.     How to add a user to the system? To add or register a new user to the system, any of the previously registered users or the programmed user should send number ‘3’ as a message to the system. Then the user will receive a message template having the user name and the contact number. By editing and sending the received template with the details of the user to be added, the system will add the user. Below is the code snippet for adding a user. The above code adds the user details in the EEPROM as well as the user’s list. Edit the user name up to 10 characters and the 10-digit contact number within the same lines of the received message and send the same to the system. The user will be added to the system. Below is the simulation output for adding a user. Now, let’s add the previously shown unregistered user.     How to know the ON/OFF status of the loads? The user can request to send the ON/OFF status of the loads through option 1. The relay states are read from the output port which is dedicated to operate the relays. This data is used to frame the template and an SMS is sent to the requested user. The logic in framing the message is to use the ‘for loop’ to each load and then if the array index reaches the ON/OFF state, the state of that load is placed.   The message that contains the ON/OFF status of the loads is framed such that, the symbol ‘=’ is used as an identifier and the character after this ‘=’ symbol is read/written as the state of the load. The ON state is represented by numeric ‘1’ and the OFF state is represented by numeric ‘0’. In order to ON or OFF the load, this numeric character needs to be edited and the edited message is sent to the system.  The number of ‘=’ symbols and the character after this symbol are verified whenever this template is received by the system. If the number of ‘=’ symbols and the number of loads are not equal, or...
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Design and Implementation of GSM Based Industrial Automation

The main aim of this proposed project is to design and implement a flexible, cost-effective and powerful GSM Based Industrial Automation security system. A GSM based Industrial Automation system is needed for the occupant’s convenience and safety. This system helps you to detect burglary, leaking of harmful gas, smoke caused due to fire and after detecting […]

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Drawing and building electronics

I’m learning to draw these days.

It’s something I’ve wanted to do well for a long time.

And I’m seeing one challenge that you probably have had yourself when learning electronics:

“I don’t have enough time.”

This weekend I finally set aside some time.

I had several hours of free time that I dedicated to doing a course.

I finished the course, and now I have a pretty good understanding of how to use Adobe Illustrator with a drawing pad.

It’s great because now I feel my drawing skills have improved a lot.

And that gives me a great feeling of accomplishment.

Just because I set aside 4 hours on Sunday.

The only way to have time to do what you want is to set aside time for it.

Keep On Soldering!
Oyvind @ build-electronic-circuits.com

PS! Not sure what your next step is? Maybe you just need to build some circuits? Check out the eBook and component kit 9 Circuits:

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Graphene forged into three-dimensional shapes

Researchers have discovered how graphene, a single-atom-thin layer of carbon, can be forged into three-dimensional objects by using laser light. A striking illustration was provided when the researchers fabricated a pyramid with a height of 60 nm, which is about 200 times larger than the thickness of a graphene sheet. The pyramid was so small that it would easily fit on a single strand of hair.

Working of Variable Power Supply with Digital Control

A power supply is a hardware component that supplies power to an electrical device. A power supply can be given from the battery or from a hardware circuitry which converts the AC supply into the DC supply or step-down AC to step-up AC and vice-versa. A variable power supply is one which facilitates the user […]

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Wearable solar thermoelectric generator created

Engineers have introduced a new advanced energy harvesting system, capable of generating electricity by simply being attached to clothes, windows, and outer walls of a building.

Interfacing Stepper Motor to Arduino

Arduino Stepper Motor Interfacing Using Darlington IC UL2003A In this article, we are publishing a project which explains different aspects of interfacing a Stepper Motor with Arduino. Stepper motor is a specially designed DC motor which comes with advantages of both a servo motor and a normal dc motor. Compared to a normal Dc motor, the maximum rpm a stepper motor can produce is very low. But they have the advantage that they can be positioned accurately. Unlike servo motor, stepper motor can also be rotated continuously. On the basis of the winding arrangement inside, the stepper motor can be categorized into unipolar and bipolar. The stepper motor we are using here is a unipolar stepper motor named 28BYJ-48. After going through the project you can run or turn the motor to desired direction. Let’s begin our tutorial and learn how to interface a stepper motor to Arduino. Objectives of the Project Understanding the basic working of stepper motor. Interfacing of stepper motor with Arduino. Generating code for turning motor to a desired direction. Using a simple Arduino library for stepper motor interfacing. Let’s begin to build our project! Components Used Arduino Stepper Motor Interfacing – Circuit Diagram   Assemble the circuit as shown in the diagram. Components required and connections are explained below Stepper Motor 28BYJ-48 As mentioned earlier stepper motors are classified into unipolar and bipolar stepper motors according to their winding arrangement. 28BYJ-48 is a unipolar stepper motor with both windings center tapped and connected to the common pin of the ULN2003A. As per the circuit remaining four ends of the windings are connected to the output pins of a Darlington IC (ULN2003A). ULN2003 is a monolithic Darlington IC consists of seven NPN Darlington transistor pairs with high voltage and current capability. It consists of common cathode clamp diodes for each NPN Darlington pair, which makes this driver IC useful for switching inductive loads. Darlington IC is used here as the stepper motor driver for Arduino. Since 28BYJ works at 5V, we connect the com pin of ULN2003A to 5V pin of Arduino. A Stepper motor can be operated in half step mode or full step mode. Here the code is written for it to work in full step mode. The library file attached with this article includes a provision for running the motor in half step mode as well. While working in half step mode the step-angle of the motor will be reduced to half the angle in full mode. In full step mode two coils are energized at a time. The speed of rotation of the motor can be controlled by altering the delay that is applied before energizing the next two coils. The maximum RPM that a 28BYJ-48 can generate is 15 rpm. Let’s explain the coding part. The Program/Code Download Arduino Stepper Motor – Program Download Library for Arduino Stepper Motor The important aspects and subroutines of the program are explained below. At the beginning of the program, four pre-processors are defined which mention the Arduino pins which are used for interfacing. Next is the use of constants in the program. The first 3 constants are for applying delay in between two consecutive coil energizing. Next two boolean constants are used for determining direction. At the “setup()” function, the Arduino pins that are used are configured as output pins. A function named “motoInput()” is used for energizing coils by giving ‘1’ to the specified coil which is to be energized and ‘0’ to the remaining coils which are not to be energized. Since we intend to run it in full step mode, we...
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Designing of 3-Line to 8-Line Decoder and Demultiplexer

A decoder is a combinational logic circuit which is used to change the code into a set of signals. It is the reverse process of an encoder. A decoder circuit takes multiple inputs and gives multiple outputs. A decoder circuit takes binary data of ‘n’ inputs into ‘2^n’ unique output. In addition to input pins, […]

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Creative use of noise brings bio-inspired electronic improvement

Researchers are working to exploit stochastic resonance to enhance signal transmission for a new generation of devices, using single-walled carbon nanotubes. They created a summing network SR device that detects subthreshold signals, fabricated to include a self-noise component.

Physicists demonstrate using a laser to control a current in graphene within just one femtosecond

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists have now succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond. This is more than a thousand times faster compared to the most efficient transistors today.

How to make a simple touch sensor

You only need 3 components.

A transistor, a resistor and an LED.

See the video below to see how I connected it. Or skip the video if you prefer to read how to connect it.

Connect the resistor and LED in series from the positive supply to the collector of the transistor. Choose a resistor that sets the current of your LED to around 20 mA.

Connect the emitter of the transistor to the negative terminal of the supply.

Now, create two wires with exposed ends – so you can see the metal.

One goes to the positive supply. The other goes to the base of the transistor.

This is all it takes.

Now, try to touch these two wires with your finger – and the LED lights up!

The reason is that your finger acts as a resistor and will give enough current to the base of the transistor to turn it on.

This is one of the circuits you will build in «Getting Started With Electronics». Along with other fun and simple circuits, to get you started in electronics. Get it here:

http://ift.tt/2htoXCK

Keep on Soldering!
Oyvind

Copyright Build Electronic Circuits

Marantz SR-7011 Receiver – 9.2 Channel Full 4K Ultra HD – Review

Marantz SR-7011 Receiver – Review Marantz is one company that is known for making premium quality home audio and video appliances. The SR7011 is the new flagship AV receiver which carries forward the legacy of the brand’s SR 7010 model. The enhancements are notable and it gets top notch audio and video features too. You get support for immersive audio formats, along with provision for latest HD video and web streaming technologies. It also blows away the competition with its near flawless performances. It is quite pricey, but buyers get the worth of their money- beyond any question. Design: Elegant and Classy Marantz SR7011 does not look drastically different from other AV receivers from the brand. That is actually a good thing. It oozes understated elegance. The duotone effect with brushed metal center and matte curved sides is there. The big volume dial is at right side while at left side there sits the large input dial and power button. A circular display sits between two dials with blue light around. A number of other inputs and ports are also there including USB port, an HDMI (HDCP 2.2) port, headphone jack and stereo analogue input. These are however hidden by a flap that you may miss at first glance. It is also sold in a silver gold variant. Connectivity: Spoilt for Choice The truth is Marantz SR-7011 Receiver offers you so many connectivity options, you may get spoilt for choice literally.  As usual, most of the connectivity options are located at back side of the device. The rear side has inputs for composite video, analogue audio inputs, optical digital inputs. There are 7 HDMI inputs along with 3 outputs. All HDMI ports are compliant with HDCP 2.2 as well as HDR content. You also get AM / FM tuners sockets, LAN port and RS232 port. If you are the kind of person who prefers wireless setups over using a lengthy mess of wires for your appliances, the Marantz SR7011 will not dishearten you. There is inbuilt support for Bluetooth and wi-fi. The WiFi dual band2.4 GHz/5 GHz support is there. It has two subwoofer outputs. You get the standard remote control which looks classy owing to black brushed metal effect with silver trim. The remote controller layout is simple and large buttons make it ergonomic too.  You get a small display at top section of the remote. It does not take long before you get used to the remote. Geeks can opt for the intuitive Marantz remote app, available both for Android devices and their iOS based counterparts. The graphics and response is amazingly good. Features: You name it, Its’ There! The Marantz SR7011 is an AV Receiver with 9 channels. Each channel has identical configuration and provisions for stable power supply. The company’s Hyper Dynamic Amplifier Module ensures audio quality is not affected adversely regardless of the source. It also gets equipped with top quality 32-bit/192kHz DAC. The device deploys Audyssey MultEQ XT32 and Audyssey Dynamic Volume to ensure you get pristine output minus distortion and sudden hike in volume. If you are looking for support for latest surround sound formats. This device will not let you down. It supports Dolby Atmos as well as DTS: X standards. In fact it supports the Dolby Atmos 7.1.4 layout. As for HD video, there is support for 4K HDR content. Up conversion of standard definition video is supported as well. Marantz SR-7011 Receiver is Imaging Science Foundation certified and comes with a set of video calibration controls. As far as wireless media streaming is concerned you are not exactly limited to WiFi and Bluetooth....
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9 Circuits in print anyone?

Printing books is a bit complicated.

I started the process once for one of my books but gave up.

That’s why I’ve focused on eBooks.

But last year I published Electronics For Kids in print:
http://ift.tt/2jGbSKS

The trick to making it happen was to join forces with a publisher.

And now I just made a deal with No Starch Press again to also release 9 Circuits in print!

There are many steps in the process, so I can’t tell for sure when it’s going to be available.

But I sure do hope it’s ready within a couple of months.

Until then, the eBook (in PDF format) is still available from here:
http://ift.tt/2rkHzJS

Keep On Soldering!
Oyvind @ build-electronic-circuits.com

Copyright Build Electronic Circuits

PCBFox – A FREE marketplace connecting PCB manufacturers with buyers

We are very excited to announce that @ CircuitsToday, we just launched our new venture PCBFox.com. PCBFox is a great platform that connects PCB manufacturers and buyers from all over the world. The idea behind PCBFox is to setup a place for buyers to meet the best PCB manufacturers anywhere around the globe. With the high growth of IoT (Internet of Things), the number of hardware-based startups & professionals is growing each day, and a lot of them are finding it harder to get their PCBs printed. Even finding a PCB vendor locally is difficult, and since most PCB printing/manufacturing companies do not own web platforms people often have to travel a lot to get their boards printed, which delays the release of new & innovative products by these young startups. Visit PCBFox.com Prototyping is the heart of hardware development cycle. Lots of prototype PCBs need to be printed before a startup/freelance designer or even a hobbyist finalizes upon his product idea. All manufacturers registered at PCBFox specialize in prototype board printing and most of them offer faster turnarounds at an affordable cost. You can ask to print very minimum copies of your prototype boards – from as low as a single copy. While the world is revolving around e-commerce the electronics industry is far behind. Most PCB manufacturers follow traditional business methods where a buyer has to be physically present to make a purchase. PCBFox is a platform that encourages more manufacturers to step outside their comfort zone and embrace new technologies available to get more audience and business. PCBFox benefits both manufacturers and buyers; it is now easy for manufacturers to find buyers while for PCB buyers it saves a lot of time and expenses. The working of PCBFox.com is very simple. Once signed up a buyer can simply post a requirement and this will be visible to all manufacturers. Depending on the buyer’s preferences & requirements, manufacturers will quote their best prices and time of delivery. The buyer can review each proposal and award the work to the vendor who seems most fit. Once this is done the buyer and seller can discuss their terms and proceed. The best thing about PCBFox.com is that it is absolutely FREE! And it doesn’t restrict you from directly contacting a vendor. It is strictly a platform to connect buyers and sellers and we totally encourage buyers to directly contact the manufacturers, know more about them and discuss their terms before awarding a work. However, once a project is complete, we do encourage you to get back to PCBFox and rate and review your seller/buyer to help other people make the right decisions. Undoubtedly it is a long journey that awaits our new venture. If you have ANY suggestions regarding our new platform do let us know via email (info@circuitstoday.com)

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Automatic Railway Gate Control Using Arduino & IR Sensor

Automatic Railway Gate Control System Using Arduino & IR Sensor About a million people have died over the past 5 years in unmanned railway crossings all over the world. At least 1/3rd of the railway crossings are unmanned due to their remote placement and less traffic. The Automatic Railway Gate Control System using IR Sensor & Arduino focuses on systematic traffic control of railway gates that are both manned and unmanned. This project will not only make the system more reliable & precise, but also save the authorities from hiring man power to do the job. You may take it as a onetime investment. The Automatic Railway Gate Control System Project makes use of an Arduino Nano to control the whole circuit. Two Servo motors are used to open and close the railway gates. Four IR sensors are used for sensing the arrival or departure of train. The main objective is to close the railway gates when the train approaches it, so as to block vehicles from going across the track. As soon as the train moves further away from the railway crossing, the gates must automatically open to allow vehicles to cross by. Components Used Automatic Railway Gate Control System Using Microcontroller – Circuit The automatic railway gate control makes use of 3 PCB’s. One is for the Arduino Nano, which works as controller of the whole project. The other two PCB’s are needed for the IR pairs. I designed all the three PCBs on EAGLE CAD software. If you want to make etched PCB, refer both the figures given below.     If you want to make the circuit on zero PCB or breadboard refer both the figures given below.     Output of all the sensors are connected to A0, A1, A2 and A3 pins of Arduino. The pins D9 and D10 of the Arduino are PWM pins. These pins are connected to the Servo motor. Servos are controlled by sending an electrical pulse of variable width, or pulse width modulation (PWM), through the control wire. IR pair is made with dual Op-amp IC LM358.  Only one IC is required for a pair. A preset is used for calibration. IR Sensors Two IR pairs are used in the project. If you are familiar with PCB etching you can etch the PCB, but it is not necessary to use the etched PCB, you can use two IR sensors instead of one pair that is easily available in market.   If you are using ready-made IR sensors please replace “<” into “>” and “>” into “<” in the code, because output of ready-made IR sensor is invert of the sensor pair used in the project. Working   Four sensors are used in the project as two pairs of two sensors; these sensors are kept in the both side of level crossings gate as shown in Fig 1. All the sensors are connected to Arduino.   When train arrives from any side, it first cross the sensor1 after that cross the sensor2, in this way Arduino close the gate by sending the signal to servomotor. When train departure from any side it first cross the sensor2 after that cross the sensors, in this way Arduino open the gate. Servomotors are used in the gate because it is very easy to use and does not require any driver IC or circuit. Servo motor has three pins. The first pin is PWM, second is Vcc and third is GND. Servo motor receives the PWM signal from Arduino and rotates the motor at fixed angle according to duty cycle of signal. Calibration There are...
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Scientists make atoms-thick 'Post-It notes' for solar cells and circuits

A new study describes an innovative method to make stacks of semiconductors just a few atoms thick. The technique offers scientists and engineers a simple, cost-effective method to make thin, uniform layers of these materials, which could expand capabilities for devices from solar cells to cell phones.

Most useful skill I’ve learned in a long time

A couple of weeks ago I took a course.

I learned one of the most useful skills I’ve learned in a long time:

Laser cutting.

It’s a machine with a laser that moves in 2 axes.

They have one at the makerspace I’m currently at in Oslo.

You can use it to cut and engrave plates of wood in whatever shape you want.

After taking the course, I started using the machine right away. I did this intentionally because I know how easy it is to forget if you don’t start practicing right away.

First, I cut out a laptop stand design I found online.

The first version turned out super small. But the next version was just perfect. I made it!

Next, I decided to try out my own design.

So I made a heart-shaped birthday card for my wife.

Which she loved!

Now, I’ve also made a custom-designed laptop-stand, and I’ve engraved the painting “The Scream” by Edvard Munch into a piece of wood.

Check it out here:

The point is, I’ve used it a lot. Starting out with pre-made designs, then slowly trying out my own.

I’ve made plenty of mistakes, but now I feel comfortable creating my own ideas on it.

(If you have a makerspace near you that has a laser cutter, I definitely recommend learning how to use it.)

And this same principle also applies to electronics.

It’s great to learn from articles and books.

But if you don’t build circuits, make mistakes and get experience – your progress will be very slow.

In my eBook 9 Circuits, you’ll get practice building circuits that you’ll know will work when connected properly.

Which will be extremely helpful for you when you want to start building your own designs.

Learn more here:
http://ift.tt/2rkHzJS

Keep On Soldering!
Oyvind @ build-electronic-circuits.com

Copyright Build Electronic Circuits

Variable Resistor – Working, Construction, Types & Applications

Variable Resistor – Working, Construction, Types & Applications One of the critical pieces in an electric circuit, the resistor is the most omnipresent electronic component. Available in wide varieties, these resistors can be used in various applications.  Resistors are broadly classified as fixed and variable resistors, according to the type of resistance value they offer. Here, in this article we shall discuss about variable resistors, its definition, types and uses. Let’s start! What is a Variable Resistor? A variable resistor is the type of resistor which changes the flow of current in a controlled manner by offering a wide range of resistances. As the resistance increases in the variable resistor the current through the circuit decreases and vice versa. They can also be used to control the voltage across devices in a circuit too. Therefore, in applications where current control or voltage control is needed, these type of resistors come handy. Figure 1 shows some real life variable resistors. Symbolic Representation The variable resistor is represented by a zig-zag line and an arrow across (or above) it, like that shown in the figure below.   Variable Resistor: Working Principle and Construction When we use the term variable resistor, it means we are talking about linear resistors by default. Linear resistors, as we know are those resistors whose resistance remains constant, even when the voltage and current through it changes. The voltage and current follow ohm’s law and are proportional to each other. A typical variable resistor has 3 terminals. Out of the three, two are fixed terminals at the ends of a resistive track. The terminals are made of conducting metal. The other terminal is a moving terminal, mostly known as the wiper. It is the position of this terminal on the resistive track that decides the resistance of the variable resistor.   These resistors offer a different resistance value, which means their resistance values can be adjusted to different values so as to provide the necessary control of current and/or voltage. To do so, a resistive strip is placed in between two fixed terminals of the device, a third terminal which is a movable one, is made to glide over this strip. Recall your basics of resistance; the resistance of a material is directly proportional to the length of the material.  Yes, that’s exactly what is used here.   The arrow placed on the resistive strip (arc shaped track), indicates the current position of the wiper terminal. Let’s suppose the wiper is placed at position “a”{figure 5(a)}, we can say that it divides the resistive track into two tracks of different lengths, from terminal 1 to point a and the other track being from point a to terminal 3. Our point of focus is the second length, as that is what decides the output of the resistor. As we move the wiper towards terminal 3, we see that the effective length decreases. So what will happen to the resistance offered by the pot? It will decrease. The resistive strip can also be laid down in a straight manner and the wiper in this case is called a slider. Its position cannot be seen or confirmed , therefore a stopping mechanism is needed to be integrated to prevent over rotation. Therefore, the main part of a typical variable resistor is the resistive material. The resistive material can be either of the following types: Carbon Composition:  One of the most common type, this material is made from carbon granules. Its low cost, reasonably low noise and lesser wear than other materials made it popular among the manufacturers. However, their inaccuracies of...
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Class A Amplifier Circuit Working and Applications

We have already discussed, the classes and classifications of power amplifiers in our earlier articles. The power amplifier circuits are used to deliver high power to drive the loads likes loudspeakers. The power amplifiers are classified based on their mode of operation that is the portion of the input cycle during which the collector current […]

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Potentiometer

Potentiometer – Working, Circuit Diagram, Construction & Types Resistor, a small bundle of resistance, is one of the most used basic components in an electric circuit. Mostly used to regulate the current flow by adding/subtracting resistance from the circuit, these resistors are available in many shapes and sizes. These resistors can be broadly classified as fixed and variable resistors. As their respective names suggest, a fixed resistor has a single fixed value of resistance, whereas a variable resistor has resistance value over a defined range.  Out of the numerous linear and Non-linear variable resistors available, the most common is the Potentiometer. This article deals with the working principle, construction and application of a potentiometer. So let’s get started! Potentiometer (pot) The potentiomers or the “pots”, as it is commonly known in the electric circles, is a three terminal variable resistor. Out of its three terminals, two of them are fixed and one  is a varying(linear / rotary) terminal. The value of the resistance can be changed from zero to a defined upper limit, by just manually sliding the contact over a resistive strip.  As the resistance changes, the current through the circuit changes and hence according to the ohms law, the voltage across the resistive material also changes. Since it coverts rotary or linear motion by the operator into a change in resistance(hence a change in electric parameter), it can be called an electro-mechanical transducer. They are passive in nature, therefore dissipate power rather than supplying power to the circuit. In  its early days of manufacture, it was thought of like a large wire wound resistive coil,which could be adjusted so as to measure the voltage difference across it . Hence, the name “potentiometer” was given to this device, which is coined from the combination of two words: potential difference and metering. They have come a long way since then. Gone are the days of large bulky potentiometers, now what we get is quite small and easy to use and light to carry; also they have now used in wide range of applications. Now that we have had an introduction about the potentiometer, you might have a curiosity of knowing how it looks like. Figure 1 shows some practical pots, while figure 2 shows the standard symbol of the same.     It is represented by a zigzag line with an arrow pointing inwards at the center. Next lets discuss the very crux of this article, the working principle of the potentiometer. How does it work? As already discussed, a potentiometer has three terminals. When connected to a circuit, the two fixed terminals are connected to the ends of the resistive elements while the third terminal is connected to the wiper. In the circuit diagram shown  below,  the terminals of the potentiometer are marked 1, 2 and 3. The voltage supply is connected across terminals 1 and 3, positive lead to terminal one while negative lead to terminal three.  The terminal 2 is connected to the  wiper.   Now a closer look into the figure, we can see that at the current position of wiper, there are two resistive paths just like the resistor is split into two resistors. Out of these two resistors, the one having longer resistive path will have a higher resistance. This is due to the fact that resistance of a resistor depends on its length (since R=ρ). Higher the length, higher is the resistance, provided the material of the resistor and its cross-sectional area remains same. For simplicity, lets name the two resistors, R1 and R2 (Refer figure). The wiper voltage is actually the voltage...
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One-way track for microwaves based on mechanical interference

Researchers use interference in the motion of a micrometer-size drum to route microwave signals in a single direction.

Optical, electrical bistability study sheds light on next-gen high speed data transfer

Today, electrical bistable devices are the foundation of digital electronics, serving as building blocks of switches, logic gates and memories in computer systems. However, the bandwidth of these electronic computers is limited by the signal delay of time constants important to electronic logic operations. In an attempt to mitigate these problems, scientists have considered the development of an optical digital computer, and one team has gone so far as to demonstrate the optical and electrical bistability for switching in a single transistor.

Circuit Design of 4 to 16 Decoder Using 3 to 8 Decoder

A decoder is a combinational circuit constructed with logic gates. It is the reverse of the encoder. A decoder circuit is used to transform a set of digital input signals into an equivalent decimal code of its output. For ‘n’ inputs a decoder gives 2^n outputs. In this article, we will discuss on 4 to […]

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Graphene and other carbon nanomaterials can replace scarce metals

Scarce metals are found in a wide range of everyday objects around us. They are complicated to extract, difficult to recycle and so rare that several of them have become "conflict minerals" which can promote conflicts and oppression. New research shows that there are potential technology-based solutions that can replace many of the metals with carbon nanomaterials, such as graphene.

2-D Electronics' metal or semiconductor? Both

Researchers produced the first 2-D field-effect transistor (FET) made of a single material.

Varistor

Varistor – Symbol, Working, Types and Applications The small package of resistance, the resistor is used in so many circuits, in so many forms, that it is almost an omnipresent electric component. From the very basic fixed resistors, where the resistance remains unchanged, to different types of variable resistors, whose resistances change according to different factors. The variable resistors are of different types; there are ones in which the effective length of the resistive strip plays role in changing the resistors like the potentiometers and rheostats and then there are other set of variable resistors where a manual change in resistance is not possible, rather they are sensitive to physical factors such as temperature, voltage, magnetic field etc. We have already discussed the variable resistor where the resistance can be changed manually (like potentiometer and rheostats) in our previous articles. This article will guide you through the world of a resistor that is dependent on voltage, known as the Varistors. What is a Varistor? A Varistor is a varying resistor whose resistance depends on the applied voltage. The name has been coined by linguistic blend of words; “varying” and “resistor”. They are also known by the name VDR [voltage dependent resistor] and have non-ohmic characteristics. Therefore, they come under non linear type of resistors. Unlike the potentiometers and rheostats, where the resistance changes from a minimum value to a maximum value, here in Varistor the resistance changes automatically with a change in applied voltage. This Varistor has two semiconductor elements, and provides over voltage protection in a circuit, similar to a Zener diode. So how does the change in applied voltage change its resistance? Well, the answer lies in its composition. Since it is made of semiconductor material, its resistance dips as the voltage across it increases. When there is an excessive increase in voltage, the resistance across it decreases manifold. This behaviour makes them a good choice for over-voltage protection in sensitive circuits.   Image Credit A real life Varistor are shown in the above figure. You may confuse them with capacitors. However Varistors and capacitors have nothing more in common than their size and design. A Varistor is used to suppress voltage, whereas a capacitor cannot perform such functions. Varistor Symbol In its early days, the Varistor was represented as two diodes placed anti-parallel to each other, as shown in figure, due to its diode like behaviour in both directions of current flow. However, now that symbol is used for a DIAC. In modern circuits, the symbol for Varistor is shown below.       You may wonder on how es a Varistor helps in suppressing the voltage transients in a circuit? To understand this, let us first understand what the source of voltage transient is. The origin of voltage Transient in electrical circuits and sources are regardless of whether they operate from an AC or DC source, since their origin is from the circuit itself or they are transmitted from any external sources. These transients result in an increase in voltage to several thousand volts, which can prove to catastrophic for the circuit. Hence these voltage transients need to be suppressed. The L(di/dt) effect which is caused by the switching of inductive coils, transformer magnetizing currents and other DC motor switching applications, is the most common source of voltage transient. The figure below shows the waveform of an AC transient.   The connection os a Varistor in a circuit can be done as follows: In AC circuits: Phase to neutral or Phase to Phase In DC circuits: Positive to negative terminal. Now what about the resistance offered...
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Innovation could mean flexible rechargeable batteries for pacemakers

Experts have designed a flexible and organic alternative to the rigid batteries that power up medical implants.

Finally, Electronics For Kids component kit

I just received an email from Ryan who works at Jameco.

He told me they’ve created a component kit for my book Electronics For Kids.

Apparently, they’d received many emails from people wanting an easy way to buy all the components for the book.

And here it is:

https://goo.gl/oEDBHn

I haven’t tried it myself yet, but Jameco has many years experience making kits, so I’m sure they’ve done a good job.

They don’t sell the book itself yet. But he told me they would soon.

The book is available from a range of other stores. I’ve listed a few alternatives here:
http://ift.tt/2jGbSKS

Keep On Soldering!
Oyvind @ build-electronic-circuits.com

Copyright Build Electronic Circuits

New quantum phenomena in graphene superlattices

Researchers have just shown the first new type of quantum oscillation to be reported for thirty years. It is the first of its kind to be present at high temperature and on the mesoscale and sheds light on the Hofstadter butterfly phenomenon.

Tiny electrically pumped micro-lasers epitaxially grown on industry standard silicon substrates

A group of researchers successfully demonstrated record-small electrically pumped micro-lasers epitaxially grown on industry standard (001) silicon substrates in a recent study. The thresholds and footprints are orders of magnitude smaller than those previously reported lasers epitaxially grown on Si.

World first: 'Storing lightning inside thunder'

In a world first, researchers have stored photonic information on a microchip as an acoustic wave. This allows precious extra time to store, process and then redistribute the data without relying on electronics, which produce excess heat. Such a hybrid chip could have a huge impact in cloud computing and telecommunication centers, which are overheating as we churn through data on our phones.

New manufacturing process for SiC power devices opens market to more competition

Researchers are rolling out a new manufacturing process and chip design for silicon carbide (SiC) power devices, which can be used to more efficiently regulate power in technologies that use electronics. The process -- called PRESiCE -- was developed to make it easier for companies to enter the SiC marketplace and develop new products.

Ballast Resistor

According to the English dictionary, “ballast” means something that gives stability. Thus when referring to an electrical ballast, we mean an electrical device that plays an important role in maintaining the stability of the electrical circuit. However, the question you may have is how does it provide the stability? Some electric ballasts limit current while some limit voltage, depending upon the circuit in which they are used. By doing so, they reduce the risk of either over voltage or over current in the circuit and thereby enhancing the stability of the system. Electric ballast varies greatly in complexity. It can be as simple as a resistor, capacitor, inductor, combination of these or it can be as complex as the electronic ballast used in the florescent lamp. Here in this article, we shall discuss about simple electric ballast, the ballast resistor. What is a Ballast Resistor? A ballast resistor is used in a circuit to limit the current and hence prevent it from over current faults. Here, as the current in the circuit varies and increases above a particular threshold value, the resistance also starts to increase. This in turn decreases the current and protects the circuit from over current faults. Thus, maintaining the stability of the circuit. These devices are mostly connected in parallel with the load of the circuit. So we can define a ballast resistor as: “A resistor limits the current in a circuit by increasing the resistance as the current increases above a certain value.”   Now let us discuss some of its areas of application. Ballast Resistor – Uses and Applications Now let us discuss some of its areas of application. Ballast Resistor in Fluorescent Lamps As we know, fluorescent lighting is one of the popular and efficient lighting system. However, there is downside to this type of lighting system. It gets heated very fast when directly connected to the voltage source. This happens due to the uncontrollable current draw by the lamp, as soon as it is switched on. In order to avoid the overheating due to the excessive current draw, a ballast resistor is used in the circuit, mostly connected in parallel with the lamp. So what does a ballast resistor do? It simply regulates the current and reduces the voltage. However, for the lamp to light up, it needs to establish an arc between its two electrodes. For this, a high starting voltage almost equal to the supply voltage is needed. The ballast resistor, supplies the needed voltage during the start up, and then immediately after the arc is established, it reduces the voltage in addition to regulating the current flow. The figure below shows a florescent light tube connected with a ballast resistor and a starting switch.   Ballast Resistor for Automotive Applications The ballast resistors are often included in the ignition kit of automotive machines such as car engines. Due to its application, such devices are called Ignition Ballast Resistor. Use of this device reduces the risk of coil failure. It is installed in the circuit between the primary voltage source for the ignition coil and the coil stud. This helps to reduce the coil voltage and coil current, therefore with the addition of the same, the coil does not get as heated as it would without the same, thus increasing the life of the coil. However, during the starting of the ignition engine, a high voltage equal to the primary voltage source is needed. Therefore a jumper wire is often connected with the ballast resistor. This jumper wire provides the necessary voltage to make the engine start. The figure below shows...
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Medicine of the future: New microchip technology could be used to track 'smart pills'

Chemical and electrical engineers team up to create a new breed of microdevices for medical diagnostics.

Sensing with a twist: A new kind of optical nanosensor uses torque for signal processing

As electronic devices get smaller, their ability to provide precise, chip-based sensing of dynamic physical properties such as motion become challenging to develop. An international group of researchers have put a literal twist on this challenge, demonstrating a new nanoscale optomechanical resonator that can detect torsional motion at near state-of-the-art sensitivity. Their resonator, into which they couple light, also demonstrates torsional frequency mixing, a novel ability to impact optical energies using mechanical motions.

Step Down Transformer

A Transformer is a static apparatus, with no moving parts, which transforms electrical power from one circuit to another with changes in voltage and current and no change in frequency. There are two types of transformers classified by their function: Step up Transformer and Step down Transformer.

A Step up Transformer is a device which converts the low primary voltage to a high secondary voltage i.e. it steps up the input voltage. A Step down Transformer on the other hand, steps down the input voltage i.e. the secondary voltage is less than the primary voltage.

The following images shows a simple demonstration of the use of Transformers (both Step up and Step down Transformers) in a typical Transmission System.

Real Time Application of Step Down Transformer

The voltage from the Power Plant or Generation Station is around 20kV. In order to transmit this voltage over long distances, it is stepped up to 440kV using a Step up Transformer. This voltage with increased levels is then transmitted to a distribution station.

At the distribution station, the 440kV is reduced to 11kV using a Step down Transformer. The voltage with decreased level is then made ready for consumer use.

Before going in to the details of the Step down Transformer, we will first see the working principle of a transformer in general. 

Also read Introduction to Transformers

Principle of Working of a Transformer

An electrical transformer works on the principle of Mutual Induction, which states that a uniform change in current in a coil will induce an E.M.F in the other coil which is inductively coupled to the first coil.

In its basic form, a transformer consists of two coils with high mutual inductance that are electrically separated but have common magnetic circuit. The following image shows the basic construction of a Transformer.

How Transformer Works?

The first set of the coil, which is called as the Primary Coil or Primary Winding, is connected to an alternating voltage source called Primary Voltage.

The other coil, which is called as Secondary Coil or Secondary Winding, is connected to the load and the load draws the resulting alternating voltage (stepped up or stepped down voltage). 

The alternating voltage at the input excites the Primary Winding, an alternating current circulates the winding. The alternating current will result in an alternating magnetic flux, which passes through the iron magnetic core and completes its path.

Since the secondary winding is also linked to the alternating magnetic flux, according to Faraday’s Law, an E.M.F is induced in the secondary winding. The strength of the voltage at the secondary winding is dependent on the number of windings through which the flux gets passed through.

Thus, without making an electrical contact, the alternating voltage in the primary winding is transferred to the secondary winding. 

NOTE: Depending on the construction of the transformer, the voltage at the secondary of the transformer may be equal, higher or lower than that at the primary of the transformer but the time period of the voltage i.e. its frequency will not change.     

Relation Between Voltage and Turns

Let N_P be the number of turns of the coil in the Primary Winding and N_S be the number of turns of the coil in the Secondary Winding.

If the alternating voltage at the primary side of the transformer is V_P and the alternating voltage at the secondary side of the transformer is V_S, then the relation between the voltages at primary and secondary and number of turns of the coil in primary and secondary is given as follows.

V_P/V_S = N_P/N_S

Step Down Transformer

A Step down Transformer is a type of transformer, which converts a high voltage at the primary side to a low voltage at the secondary side.

If we speak in terms of the coil windings, the primary winding of a Step down Transformer has more turns than the secondary winding. The following image shows a typical step down transformer.

Example of Step Down Transformer

For example, consider the following situation. The number of turns in the primary winding of a transformer is 3000 and that in the secondary winding is 150. If the alternating voltage at the primary of the transformer is 240V, then the voltage at the secondary of the transformer can be calculated using the following equation.

V_P/V_S = N_P/N_S

Here, N_P is primary winding turns = 30000

N_S is secondary winding turns = 150

V_P is voltage at the primary winding of the transformer = 240V

V_S is the voltage at the secondary of the transformer =?

Using the above equation, V_S = (V_P * N_S)/N_P = 240*150/3000 = 12V

Hence, the voltage at the secondary winding of the transformer is 12V, which is less than that at the primary. Therefore, the transformer in this subject is a Step down Transformer. 

Read this intereseting post on TYPES OF TRANSFORMERS

Power in Step down Transformer

The power in a transformer is measured using the product of voltage and current. The power in a transformer is rated in Volt – Amps VA (or Kilo Volt – Amps kVA for larger transformers).

Ideally, the power in any transformer is constant i.e. the power available at the secondary of the transformer is same as the power at the primary of the transformer.

This is even applicable to a step down transformer. But, since the voltage at the secondary of a step down transformer is lesser than that at the primary, the current at the secondary will be increased in order to balance the total power in the transformer.

Current and Voltage Relation in Step Down Transformer

We will now see how this works. Let V_P be the voltage at the primary, I_P be the current at the primary and P_P be the power at the primary side of the transformer.

We know that the power can be calculated by simply multiplying the voltage and current. Hence, the power at the primary side of the transformer is given by

P_P = V_P * I_P

Similarly, let V_S be the voltage at the secondary, I_S be the current at the secondary and P_S be the power at the secondary side of the transformer.

The power at the secondary of the transformer is given by

P_S = V_S * I_S

Since, the power in a transformer is constant, P_P = P_S.

Which means, V_P * I_P = V_S * I_S

As V_S is less than V_P in a step down transformer, I_S has to be more than I_P. Hence, the output voltage in a step down transformer is less than that of the primary voltage and the output current is more than the input current.

From the above analysis, we can define a Step down transformer as a device which converts a High Voltage and Low Current alternating source to a Low Voltage and High Current alternating supply.

NOTE: The above power calculation is for an ideal transformer where there are no loses. Practically, there will loses in the form of iron losses and copper losses that should be taken in to consideration (even though the losses are small).

Where Step down Transformer is used?

• All the street transformers which we see near our homes are step down transformers. They take a 11kV alternating voltage at the primary and convert it to 230V for distributing it to our homes.  
• Before the wide usage of switching power supplies, almost all low voltage wall adapters use step down transformers.

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Digital Potentiometer

Digital Potentiomter – Working, Internal Structure & Applications One of the most common types of variable resistors is the potentiometer. Potentiometer or “pots”, are three terminal devices, used to vary the resistance in a circuit. We have dealt in depth about this topic, in our article “potentiometers”, if you want to learn about the basics of a pot, this article will be useful for you. Pots that ware available nowadays varies in operation. Some are mechanically operated, while some are digitally controlled.   Image Credit – SparkFun Before we proceed, let’s have a quick review of how the basic working of a potentiometer. How Digital POT Works? Generally, a pot has a resistive material over which a wiper moves. This movable wiper controls the resistance offered by the potentiometer. A pot as we know has three terminals, a positive, ground and a wiper terminal. The position of the wiper decides the resistance of the pot. To understand its significance, lets consider the figure below.   Look at the above figure. What do you see, a simple resistor right? Well, there’s more to that. The numbers 1, 2, 3 here indicate the terminal numbers. Terminal 2, indicates the wiper terminal. Now the resistive part between terminals 2 and 3 is nothing but the effective resistance of the pot. So according to this, the effective resistance of the pot, for the first case, where the wiper terminal is nearer to the terminal 1,is higher than that for the second case( wiper terminal nearer to terminal 3). Now, how to change the position of the wiper? you may wonder. The wiper movement can be controlled either mechanically or digitally. This difference in control of the wiper, brings us to the classification of pots into mechanical and digital potentiometer. The figure below shows a schematic of a mechanical and a digital potentiometer.   First, let’s see what is common to both of them: Basic structure: Both have three terminals and a resistive element, over which the moving terminal glides. Adjustable Nature: The resistance of both types of pots can be adjusted to the need of the circuit, and offer wide range of resistances. Now, if they are similar in structure and nature what’s the difference between the two? Well, the biggest difference between the two is in their control section. Control section is nothing but the part of the pot that controls the position of the wiper. In mechanical potentiometer, the wiper movement is done by hands or we can say physically. In digital potentiometer, the wiper connection is electrical and the movement of the wiper is controlled by digitally controlled signals, typically given out by a computer or a microcontroller. The types and working of a mechanical potentiometer has been already discussed in our articles “potentiometers”. Here in this article, we will deal with the working of digital potentiometers and their advantages over mechanical pots. What is a Digitally Controlled Potentiometer? A digital potentiometer or a digiPOT (Electronic Potentiometer) as it is commonly called can be said to be a digital version of the mechanical potentiometer or a rheostat. It offers the same analogue functions as a rheostat or a potentiometer that is control of current or voltage. It is controlled by digital protocols like I2C , SPI, and basic up down and push button protocols. This device allows a more accurate robust and faster calibration process, with smaller voltage glitches. How is digiPot different from the traditional Pot? The Build: Mostly, the digipot is built from a resistor ladder integrated circuit. Here, at each step, there is a switch that connects it...
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Kicad or Eagle?

I was enjoying my freshly brewed morning coffee as a friend of mine arrived at the office.

(Well, it’s not really my office, but an awesome makerspace I sometimes go to.)

We had a long chat about Kicad and Eagle.

These are two popular applications for designing circuit boards.

I have been a long time Eagle user.

He’s a Kicad user.

But in the coffee roaster project I’m hired to work on, they use Kicad.

So, I had to switch.

It was surprisingly easy to switch.

And I kind of liked Kicad.

Kicad is a free open-source software that is developed by volunteers.

Eagle is a commercial software owned by Autodesk. But free for hobbyists and students.

(And it’s cheap if you want to use it for commercial projects.)

At the end of our conversation, I concluded that I think I will be using Kicad for my future projects.

Then my problems started.

I bought a new computer.

After 8 years of service, it was time to retire my old Dell laptop.

I’ve always been a PC guy.

Using Windows and Linux.

But I decided that this time I will buy a Mac, and see for myself what all the fuzz is about.

To make a long story short – it turned out Kicad was unusable on my new Macbook Pro 13 inch!

It just runs really slow.

So I had to use my old Dell laptop to work on the coffee roaster project!

During the last week, more issues have come up with Kicad.

I’ve always found a way to work through them.

But it’s left me with this feeling that maybe I should stay with Eagle.

I’m thinking that since Eagle is a commercial software they will use more resources to make sure there are no issues that might drive customers away.

I’m gonna design another project in Eagle soon.

Then I’ll write an article with my conclusion.

But the good news is that it was very easy to switch from Eagle to Kicad.

So if you, for example, take my course on Circuit Board Design with Eagle, you can still switch to Kicad in the future =)

I’ll let you know when the article is out.

Keep On Soldering!
Oyvind @ build-electronic-circuits.com

Copyright Build Electronic Circuits

Rheostat – Working, Construction, Types & Uses

Rheostat – Working One of the most omnipresent electric components is the resistor. In applications where variable resistance is required, potentiometers and rheostat are mostly preferred. We have already discussed about potentiometers in our previous article about the same. Here we shall discuss about rheostat in detail. What is a Rheostat? Rheostat is a type of variable resistor, whose resistance can be changed so as to change the amount of current flowing through a circuit. This device, was named “Rheostat” using two Greek words “rheos” and “statis” (meaning a current controlling device), by an English Scientist Sir Charles. It has two terminals, out of which one is fixed and the other one is a moving terminal. Some rheostats have three terminals just like potentiometer, although only two terminals are used (Only one of the two fixed terminals and the moving terminal are used). Some practical rheostats are shown below.   Unlike potentiometers, these devices have to carry significant amount of current. Hence, wire wound resistors are mostly used for the construction of rheostats. In a circuit diagram, a rheostat is often represented as shown below.     So on what basis does the rheostat work? Let’s get to know that in the next section. Working principle of a Rheostat In order to understand, the significance of rheostat and its working principle, let us refresh our basic of electric circuits. The three main parameters of an electric circuit are: voltage applied to the circuit, current through the circuit and the resistance offered by the circuit. Now, we know these parameters are interdependent. That is, to change the current, we can either change the voltage applied or change the resistance of the circuit. When we use a rheostat in a circuit, what we are basically doing is changing the resistance of the circuit, to change the current. As the current and resistance are inversely proportional, if a decrease in current is required, we will increase the resistance of the rheostat. Similarly, if an increase in current is required we would simply decrease the resistance of the rheostat. Now you may wonder whether there is there a maximum limit up to which the resistance can be decreased or increased in a rheostat. The answer is yes, there is. For every rheostat comes with a resistance rating, like for example if a rheostat has a rating of 50KΩ, the minimum resistance it can offer is 0 and maximum is 50kΩ. So how do we change the resistance of the rheostat? For this, rewind your basics of resistance. In our previous article “Resistivity and Electrical Conductivity – Complete Guide”, we have discussed the parameters on which resistance of a material depends.  The main three factors on which the resistance of a material depends is its length, area of cross-section and the type. Here, in this device, the effective length is changed using a sliding contact. A rheostat as already mentioned has a fixed and a moving terminal. The effective length is that between the fixed terminal and the position of the sliding terminal on the resistive path.  As the slider moves, the effective length changes thereby changing the resistance of the rheostat. Since resistance is directly proportional to the length, as the effective length increases, the resistance increases. Similarly, as the effective length decreases, resistance offered by the rheostat decreases. Now that the working principle is quite clear, let’s see, the construction and types of rheostats. Construction of Rheostat: The construction of rheostat is same as that of a potentiometer, as discussed in detail in our article about potentiometers.  Similar to the potentiometer, a rheostat...
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Ultrasonic Blind Walking Stick Using Arduino

Ultrasonic Blind Walking Stick According to the WHO, about 30 million people are estimated to be permanently blind worldwide. These people are totally dependent on others. They even cannot walk on their own. We have created designed and built an “Ultrasonic Blind Walking Stick” device which will help blind people to walk with ease independently. As a simpler version, we have used only one ultrasonic sensor in this project. For better accuracy and assistance two or three sensors can be used. The main objective of this project is to help blind people to walk with ease and to be warned whenever their walking path is obstructed with other objects, people or other similar odds. As a warning signal, a buzzer is connected in the circuit, whose frequency of beep changes according to the distance of object. The closer the distance of obstruction, the more will be the buzzer beep frequency. We can say that the beep frequency is inversely proportional to the distance. The main component used for this device is the ultrasonic sensor.  The ultrasonic sensor transmits a high frequencys ound pulse and then calculates the time to receive the signal of the sound echo to reflect back. The sensor has 2 circles. One of them acts as the transmitter and transmits the ultrasonic waves. The other one acts as a receiver (mostly a small microphone) and receives the echoed sound signal. The sensor is calibrated according to the speed of the sound in air. With this calibrated input, the time difference between the transmission and reception of sound pulse is determined to calculate the distance of the object. This circuit is powered by a 9-volt battery through a switch. Components Used Circuit In the circuit an Arduino Nano is used as the platform. Ultrasonic sensor is connected to Arduino. The ultrasonic sensor has 4 pins – Vcc or 5 volt which is connected to 5 volt pin of Arduino Trigger which is connected to D12 pin of Arduino Echo pin is connected to D11 pin of Arduino Ground which is connected to GND pin of Arduino. Positive terminal of 9-volt battery is connected to Vin pin of Arduino through a DPDT switch and the negative terminal is connected to GND pin of Arduino. A buzzer is connected between D9 pin of Arduino and GND pin. The whole project has been designed on Eagle. The same circuit prototype can be made using a breadboard or zero PCB. The circuit diagram and PCB design are given below.     Working   As shown in diagrams there are two openings in Ultrasonic sensor first is transmitter (or Trigger) and second is receiver (or Echo). Ultrasonic sensor sends high frequency pulses, these pulses reflects from object and takes as Echo, time between echo and Trig is measured by the microcontroller or Arduino which is directly proportional to distance. The speed of sound is 341 meter per second in the air, and the distance between sensor and object is equal to time multiplied by speed of sound divided by two. Distance = (Time * Speed Of Sound) ÷ 2 After the distance measurement, Arduino makes a beep format using buzzer, when distance is high, frequency of beep is decreased and beep frequency is increased when distance is low The range of HC-05 Ultrasonic sensor is not high, it can only measure 50cm in open space, for more distance many other powerful sensors are available in the market.     Program Code Download Program Code Code file is given in the link, just download this file and upload to Arduino. In the code, a library...
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Self-folding electronics could enable advanced robotics

As demand grows for more versatile, advanced robotics and other technologies, the need for components that can enable these applications also increases. Producing such components en masse has been a major challenge. But now, researchers report that they have developed a way to help meet this need by printing electronics that can fold themselves into a desired shape.

'Peel-and-go' printable structures fold themselves

Researchers have created a printable structure that begins to fold itself up as soon as it's peeled off the printing platform.

Artificial 'skin' gives robotic hand a sense of touch

A team of researchers from the University of Houston has reported a breakthrough in stretchable electronics that can serve as an artificial skin, allowing a robotic hand to sense the difference between hot and cold, while also offering advantages for a wide range of biomedical devices.

Common Base Amplifier Circuit Working And Its Applications

An Amplifier circuit is used to increase the strength of the signal. The amplifier circuit uses the power supply to increase the signal strength. The amplification provided by the amplifier circuit is measured in terms of Gain of an amplifier. The gain of the amplifier is the ratio of output to input, which is always […]

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An embarrassing confession

There I was, a 20-year-old electronics student, not understanding how the transistor worked.

It’s a bit embarrassing to admit that it took me so long.

The story starts back in my first year at University.

I had played around with electronics since I was 14, and I was able to build circuits.

But I didn’t understand how most of them worked.

Now, I was in one of my first lectures at the University and the professor was explaining how electrons moved through the transistor.

This continued for many lectures.

I had no idea what he was talking about.

In my head I knew that you needed a closed loop to get a circuit to work:

A path between plus and minus on the battery.

But I could not see how that related to the three legs of the transistor.

And there was no way that I was going to admit that by asking “stupid” questions in front of the whole class.

So I kept silent while listening to the professor going on and on about “n-doped and p-doped semiconducting materials”.

The transistor must be really hard to understand, I thought to myself. Maybe this is not for me?

Fast forward a few weeks/months.

I don’t remember how long it took, but one day I was looking at some examples, and it all clicked.

I finally understood how it worked!

It was a moment of mixed feelings.

But because when I finally got it, I realized it was very simple.

One part of me said “Great! Now I get it.”

But the other part of me said: “Why didn’t someone just tell me this from the start!?”

It was so easy!

I’ve never really had any desire to be a teacher.

But the feeling of not understanding something as important as the transistor for such a long time, then learning that it’s actually really easy – that frustrated me.

And it started giving me this urge to inform people about this.

To let them know that it’s not that hard.

Fast forward a few years and I started writing books, articles, and videos.

With the intention of informing people about the things in electronics that I realized was actually pretty easy.

Because I wanted more people to build cool things with electronics.

Ohmify is my most up-to-date resource where I teach electronics.

It’s a membership-site with courses that teach you what you need to be able to build your own things with electronics.

Learn more about Ohmify here:
https://ohmify.com/join

And I’m constantly working on improving it.

I actually just got a research grant from the Norwegian government to further develop Ohmify into something better and bigger.

But more on that in another email.

Keep On Soldering!
Oyvind @ build-electronic-circuits.com

Copyright Build Electronic Circuits

Rain Sensing Wiper using Arduino and Servo Motor

Automatic Rain Sensing Wiper Using Arduino  This project is designed to build a car wiper that automatically detects the rainfall intensity and regulates the frequency of wiper operation. It is built, using Arduino UNO board. A rain sensing module is used for measuring the intensity of rainfall. And a servo motor is used for controlling the wiper movements. An LCD module is also attached to the controller for displaying the rainfall intensity. By measuring the amount of rainfall , controller will adjust the speed of servo motor . Servo is controlled by generating PWM signal at its signal line.   Objectives of the Project Measuring the amount of rainfall. Displaying the intensity of rainfall in an LCD module. Controlling the servo motor speed according to the output from the sensor module.   Lets begin to build our project – Rain Sensing Car Wiper   Assemble the circuit as shown in diagram! Important connections are explained below. MH-RD rain detector is the sensor module that we are using here. The module  have 4 pins: Vcc, A0, D0 and Gnd. Vcc and Gnd are connected to the supply pins of the Arduino.  A0 and D0 are the analog and digital output pins of the module respectively. Since we need continuous change in rainfall, we will make use of the A0 pin instead of D0. The analog out from senor is then connected to one analog input pin of Arduino. As mentioned earlier a servo motor is used here for wiper movements. Servo motor is a special kind of high torque dc motor whose shaft can be adjusted to desirable position by generating an appropriate PWM signal at its signal line. Here we connect the signal line of servo to one of the PWM pin of Arduino(i.e. digital pin 9). Next comes is the LCD module, which is for displaying the rainfall intensity. Interfacing of Arduino to 16×2 LCD is quite simple. JHD162A is the LCD module used here. JHD162A is a 16×2 LCD module based on the HD44780 driver from Hitachi. The JHD162A has 16 pins and can be operated in 4-bit mode (using only 4 data lines) or 8-bit mode (using all 8 data lines). Here we are using the LCD module in 4-bit mode. To facilitate communication between Arduino and LCD module, we make use of a built in library in Arduino <LiquidCrystal.h> – which is written for LCD modules making use of the Hitachi HD44780 chipset (or a compatible chipset). Control pin RS, RW and En are directly connected to arduino pin 13, GND and 10. And data pin D4-D7 is connected to 7,6,5 and 4 of Arduino. When the device is switched ON, the servo motor will turn the wiper to  zero degree position.  After that the controller will continuously checks the signal from rain sensing module. If the signal from the module goes beyond a minimum value, the servo motor begins to operate .  The speed of operation of servo will be varied according to the strength of the signal. And the intensity of rainfall will be displayed on the LCD according to the signal strength . The Program/Code    Download Program   At the beginning ,program will continuously check the reading from the rain sensor. A library called “Servo.h” is used here for servo operations. By calling the inbuilt function “myservo.write(angle)” we can turn the servo shaft to desired angle. One more library called “LiguidCrystal.h” is used  , to facilitate communication between Arduino and LCD module. At the interfacing section the LiquidCrystal library is first initialized and then pins are defined using the command “LiquidCrystal lcd(RS, E, D4,...
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Marantz SR-6011 AV Audio & Video Component Receiver, Black

Marantz SR-6011 Receiver Marantz is one brand that is known for making some of the most feature rich and premium class AV receivers and they are eyed by people seeking entertainment minus compromise. If you are looking for a top notch performer in this segment, the SR6011 from Marantz is worth a consideration. This versatile AV receiver sits somewhere between the siblings SR5011 and SR7011. It is quite future proof- in terms of features and performance wise trounces most segment rivals.   Design: Minimalistic but Elegant The Marantz SR-6011 Receiver has a minimalistic yet classy design. Its curved matte panel is what makes it stand apart from most segment rivals. The center of the box has a nice lovely brushed finish, and the black version looks really elegant. Some people may also like the shiny silver variant of the model. The display panel is nice as it does not overwhelm you with information, but you get to know what is required for operation. The thick flap at bottom conceals buttons and sockets. There you can get eight HDMI inputs, USB port, output for headphones, and port for the calibration microphone. The nice thing is the HDMI inputs support HDCP 2.2 and 4k content- bliss for media lovers. There are rows of buttons for controlling sound modes and radio presets. At the back of the device, you will find more ports and connectivity options. You get 7 additional HDMI 2 inputs along with 2 outputs. Again, they all support HDCP 2.2 and 4K HDR compatible content. There are four digital audio inputs (coaxial x 2, optical x2), analogue AV ports, 7.1-channel analogue inputs to cater to user needs. Apart from these, you get RS-232 ports, Ethernet port, IR ports, and a remote control. Features: The more- the merrier The Marantz SR6011 is nine-channel receiver with 185W output per channel. The feature set is impressive to say the least. It will satisfy even the more demanding type of users. It supports Dolby Atmos, DTS-HD Master Audio, DTS: X, Dolby TrueHD and Dolby Surround- quite a handful! Nowadays, all AV receivers offer support for wireless media streaming- more or less. In this respect the Marantz SR6011 scores full marks. It has in built Wi-Fi and Bluetooth. You also get support for major popular web streaming services like Spotify and Internet radio. Apple Airplay is supported too. Playing back hi-res files including formats like FLAC, WAV. The only thing you may miss is lack of support for HEOS multi-room. The audiophiles will fall in love with the device. It has certification of Imaging Science Foundation. Things can seem a gargantuan overdose for novices in tech- as it is. Just to get an idea, the device has set up to convert both HD and SD sources to 4K resolution. The device is Control4 SDDP compatible which ensures easy integration with the home automation equipment. Setting up: A geek’s dream There is no denying the reality the Marantz SR6011 is one multifaceted and complex AV receiver. It is what a true geek can dream about. However, that does not necessarily mean a technologically inept person cannot use the device! You need to connect the SR6011 to a TV and then the Setup Assistant will walk you through the rest of the setup process. It does not take a long time either. The informative graphics and crisp descriptions ease the task. However, you need to be careful before delving into the Audyssey MultEQ XT32 calibration system. A cardboard tripod and microphone is what you need to let the setup run and set speakers accordingly. There are a...
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GSM/GPRS Module

GSM GPRS Modules are one of the commonly used communication modules in embedded systems. A GSM GPRS Module is used to enable communication between a microcontroller (or a microprocessor) and the GSM / GPSR Network. Here, GSM stands for Global System for Mobile Communication and GPRS stands for General Packet Radio Service.  

A GSM GPRS MODEM comprises of a GSM GPRS Module along with some other components like communication interface (like Serial Communication – RS-232), power supply and some indicators. With the help of this communication interface, we can connect the GSM GPRS Module on the GSM GPRS MODEM with an external computer (or a microcontroller).

GSM / GPRS Modules allow microcontrollers to have a wireless communication with other devices and instruments. Such wireless connectivity of microcontroller opens up to wide range of applications like Home Automation, Home Security Systems, Disaster Management, Medical Assistance, Vehicle Tracking, Online Banking, E – Commerce etc. to name some.

Before going in to the details about the GSM/GPRS Module, we will first see a few basic things like GSM, GPRS, MODEM, Module and System. 

Also read HOW TO INTERFACE GSM/GPRS MODULE WITH 8051?

What is GSM?

GSM or Global System for Mobile Communication is a Wireless Communication standard for mobile telephone systems. It was developed by the European Telecommunications Standards Institute (ETSI) as a replacement to the 1^st Generation Analog Cellular Network.

Hence, GSM is often called as the 2^nd Generation Digital Cellular Network or simply 2G. From its deployment in Finland in the year 1991, GSM has grown rapidly with an estimated market share of over 90% in more than 200 countries.

What is GPRS?

GPRS or General Packet Radio Service is an extension of the GSM Network. GPRS is an integrated part of the GSM Network which provides an efficient way to transfer data with the same resources as GSM Network.

Originally, the data services (like internet, multimedia messaging etc.) in the GSM Network used a circuit – switched connection. In this type, the access time for the network are long and the charges for the data were based on the connection time. Also, this type of connection is not suitable for transmitting bursts of data.

With the integration of GPRS, a packet – switching based data service, in to the GSM Network, the scene of data services has changes. In GPRS based packet – switching networks, the user device doesn’t hold the resources for a continuous time but efficiently uses a common pool.

The access time in GPRS is very small and the main advantage is that it allows bursts of data to be transmitted. Also, the charges for data are based on the usage and not on the connection time. 

Related Post: Arduino Based Home Security System using GSM Module

Difference between a Module, MODEM and Mobile (System)

A GSM/GPRS Module is a device or chip that is actually responsible for the wireless communication with the GSM Network.

A GSM/GPRS MODEM is device that modulates and demodulates the signals from the Wireless Network and allows internet connectivity. A GSM MODEM generally consists of a GSM Module along with some other components like a SIM Card, a device to modulate and demodulate the signals and power supply.

A System, like a mobile phone for example, is a complete device that has a GSM Module (might be integrated in the processor), a GSM MODEM (even this might be integrated) and other components like processor, screen, keypad, speakers, microphone etc.    

Check out this interesting post on Differences between GSM and CDMA.

Speaking of GSM/GPRS MODEMS, they are a class of Wireless MODEMS, which use the GSM/GPRS Network for transmitting and receiving data. Wireless MODEMS are also available for different cellular networks like CDMA, GSM, UMTS and LTE and different data services like GPRS, EDGE, HSDPA and LTE.

GSM/GPRS Module

A GSM/GPRS Module is an IC or chip that connects to the GSM Network using a SIM (Subscriber Identity Module) and Radio Waves. The common radio frequencies in which a typical GSM Module operates are 850MHz, 900MHz, 1800MHz and 1900MHz.

Since it is not possible to interface a GSM/GPRS Module directly to an external device like a microcontroller, we need a setup like shown in the following image.

It consists of the GSM/GPRS Module, slot for inserting a SIM Card, RS-232 Interface for connecting with computer or a microcontroller, signal status LED, power supply and a provision for connecting microphone and speaker.

Each GSM/GPRS Module is unique and it can be differentiated by its IMEI Number. IMEI or International Mobile Equipment Identity Number is a 15 – digit unique number associated with mobile phone, satellite phones and other GSM Network devices.

   Read this interesting post: GSM Controlled Robot using Microcontroller

With the help of this GSM/GPRS Module, we can do the following tasks.

• Make, receive or reject voice calls
• Send, receive or delete SMS messages in the SIM Card
• Add, read and search the contacts in the SIM Card
• Send and receive data to / from the GSM/GPRS Network through GPRS

All the above mentioned tasks can be accomplished with the help of ATtention Commands or AT Commands. AT Commands are a part of Hayes Command Set, which are defined originally for a modem. GSM Network also implements a similar AT like commands for its GSM Modules.

The processor or controller to which the GSM/GPRS Module is connected to, is responsible for sending the AT Commands to the module. In response, the GSM Module performs command specific tasks like answering a phone call, send an SMS Message, etc.

Even through the AT Commands may seem generic, it is advisable to refer with the data provided by the manufacturer of the GSM Module for correct and complete list of AT Commands. 

Also Read: WIRELESS ELECTRONIC NOTICE BOARD USING GSM AND 8051

Syntax of AT Commands

Generally, AT Commands consists of three parts: the Prefix, the Body or Command and the Termination. The Prefix part of the command consists of either “AT” or “at”. The body or command is the actual command given to the GSM Module. The Termination character is by default Carriage Return <CR>.

Before seeing an example, we should know that AT Commands are categorized in to three types: Basic AT Commands, S Parameter AT Commands and Extended AT Commands.

Example for the Basic Commands: ATCMD1<CR>, where AT is the prefix of the command line, CMD1 is the body of the command and <CR> command terminator character.

NOTE: Basic commands never begin with +.

Example for Extended Commands: AT+CMD1<CR>.

NOTE: Extended AT Commands always begin with +.

NOTE: The Carriage Return <CR> will be omitted from the next command example or syntax. You have to assume them as a part of the command even though they are not inserted in the text here.    

Types of AT Command Operations

Based on the operation performed by the AT Commands, they are again divided in to four types: Test Commands, Read Commands, Write Commands and Execution Commands. We will now see the definition and syntax of all these command types.

Test Commands: These commands are used to test whether the command exists (supported by the GSM GPRS Module) or not and also checks for the range of a command’s subparameters. When a Test Command is given to the GSM GPRS Module, it returns the list of all the parameters and also the range set of the parameters.

The syntax of a Test Command is ATCMD1=?<CR>

Example for Test Command: AT+CGMI=? (Request manufacturer identification)

Read Commands: Read Commands will return the current value of the parameter. Using these commands, we can read the current settings of the GSM GPRS Module.

The syntax for Read Commands is: ATCMD1?<CR>

Example for Read Command: AT+CSCA? (Query for Service Center)

Write or Set Commands: Set Commands will attempt to change or modify the settings of the GSM GPRS Module by setting a new parameter for the particular command.

The syntax for Set Commands is: ATCMD1=value1,value2,value3…valuen<CR>

An example for Set Command: AT+CMGF=1 (Set Message format to TEXT Mode).

Execution Command: These commands perform an operation like send an SMS, retrieving information about battery charging status etc. They read the non – variable subparameters that are affected by the GSM Module.

Syntax of Execution Commands: ATCMD1<CR>

Example for Execution Commands: AT+CMGS=<number><CR> <text message> <CTRL-Z> (Sends text message to the number).

Information Responses and Final Codes

After sending the AT Commands to the GSM GPRS Module, we have look for the response. For example, if we send the command as AT+CGMI<CR> to the GSM Module, then the response would be as follows.

<CR><LF>Apple<CR><LF>

<CR><LF>OK<CR><LF>

Here, <CR> is Carriage Return and <LF>is Line Feed.

In a HyperTerminal, if you entered AT+CGMI<CR>, the response will look something like this.

AT+CGMI <– Command entered

Apple <– Information Response

OK <– Final Code

The syntax of the information response and final command is as follows:

<Carriage Return><Line Feed> <Information Response / Final Result Code> <Carriage Return><Line Feed>

<CR><LF><Response><CR><LF>

NOTE: The sequence of execution of commands will be first commands, then second command, followed by the rest i.e. a sequential execution of commands.

If there is an error anywhere in the execution, an error code is returned by the GSM Module and the execution of further commands is terminated.

Frequently used AT Commands

In this list, you can find out some of the most commonly used AT Commands. For a complete list of AT Commands and their definitions, it is advised to refer the manufacturer data. The <Carriage Return> or <CR> is denoted by this symbol ↲.

To check the communication between the GSM Module and the host (Computer)

AT ↲

OK

To make a voice call

ATD9848032919; ↲

To answer or receive an incoming call

ATA ↲

To redial the last number

ATDL ↲

To disconnect a call

ATH ↲

To set the message mode to text mode

AT+CMGF=1 ↲

OK

To send a text message

AT+CMGS=”9848032919” ↲

Message

CTRL+Z

NOTE: A detailed article about all the AT Commands will be updated.  

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