A. M. Bhatt

Sequence timer is used in many manufacturing industries to turn ON and turn OFF processes one by one automatically. Sequence timer is at most required when there is chain of processes – means 1st process ends it triggers 2nd process, when 2nd ends it triggers 3rd process and so on (like chain reaction !!!….).  The timings and durations of each process has to be set initially. Each process requires specific time duration. The time duration for each process in sequence is set (programmed) before the entire chain process starts. Then the 1st process is triggered. It runs for set duration and when it finishes, 2nd process starts and thus the chain starts. Each process runs for set duration and when it finishes, turns ON next process. 

The first thing we need to understand is that what it servomechanism? Servomechanism means generating error output as a difference between output feedback and control input and reduces this error until it becomes zero – that means when the system reaches desired state when the system produces desired output.  

You may have seen many micro controller based GPS receivers. The main purpose of such GPS receivers is to locate and display device latitude and longitudes (co-ordinates). These GPS receivers are built using micro controller and LCD screen. Most of the receivers display location co-ordinates only. Some may display time and date along with co-ordinates. But only few GPS receives display full information like time, date, location, height, speed, direction, number of satellite in view, validity and accuracy of signal etc. so many details.

IC 555 timer is a well-known component in the electronic circles but what is not known to most of the people is the internal circuitry of the IC and the function of various pins present there in the IC. Let me tell you a fact about why 555 timer is called so, the timer got its name from the three 5 kilo-ohm resistor in series employed in the internal circuit of the IC. IC 555 timer is a one of the most widely used IC in electronics and is used in various electronic circuits for its robust and stable properties. It works as square-wave form generator with duty cycle varying from 50% to 100%, Oscillator and can also provide time delay in circuits. The 555 timer got its name from the three 5k ohm resistor connected in a voltage-divider pattern. 

The given project demonstrates how to measure all the four parameters of greenhouse farming and monitor them continuously. It uses smart sensors like DHT11 to measure temperature and humidity, soil moisture sensor, and LDR to measure ambient light. It uses Arduino to measure all these four parameters and LCD to display their values.In greenhouse farming, it is required to monitor, control and maintain four parameters, namely- Temperature, Humidity, Soil moisture, and Ambient light. In such farms, these four parameters are continuously monitored and controlled. Maximum efforts are done to maintain required temperature, humidity, soil moisture and light to get good quality of agriculture product.

Whenever we are testing and troubleshooting any digital circuit the most required handy tool is logic probe. Logic probe is used to check HIGH or LOW logic. There may be LED or buzzer type of indication for indicating whether logic is HIGH or LOW. Like there may be: Simple LED indication – means LED glows if logic is HIGH and vice versa, different colour LED (RED – GREEN) to indicate HIGH and LOW logic, or buzzer that sounds if logic is HIGH and does not sounds if logic is LOW. The circuit consists of fewer components and very easy to build. It consists of one INVERTER chip 74LS04, one common cathode type 7-segment display and 3 diodes only.

RTC based device ON-OFF timer means it will turn ON and OFF the device at the required time. It will turn ON the device at selected time and again after the preset time, it will turn it OFF also. So, the device turns ON and turns OFF operation because automatic as per preset time schedule.  Such devices are widely used in industries. In industries, it is required to turn ON and OFF the device at a specific time. If the devices are operated for a specific time period with accurate timings then there can be less power consumption and this will directly reduce the production cost. Many industries appoint human operators to operate the device for desired time duration. But this is not a good choice as there may be a lack of accuracy.

Any 4 phase unipolar stepper motor can be driven in 3 different modes: Single coil excitation mod, double coil excitation mode, and half step excitation mode. The given project demonstrates how to drive any unipolar stepper motor in these three different modes. It uses arduino UNO board and unipolar stepper motor library to drive the stepper motor.It also controls speed (RPM) of the motor and displays the current speed and driving mode on LCD. So let us first see the circuit diagram followed by its description and working. Complete functionality of project is because of the program downloaded into arduino board microcontroller ATMega328. The program is the soul of the project. The program (also known as sketch) is written and compiled in arduino IDE software tool.

Previously, I have given arduino library for unipolar type stepper motors. It perfectly controls speed, direction, the number of revolutions, motor angle etc all the parameters of unipolar type stepper motors. But it was for only unipolar type stepper motors. As we know the stepper motor may be bipolar type also. But this library cannot control bipolar type stepper motor. So, I have decided to develop another arduino library to control bipolar type stepper motor. Here, I present Bipolar Stepper motor library in Arduino for all bipolar type stepper motors. The library has 9 different functions that can be used to rotate and control motor as per the requirements. The library is designed as per the industrial motion control requirements.

D flip-flop is used to store 1-bit information. It is called 1-bit register and stores 1-bit information when the clock pulse is applied. Actually, it latches the input to output when the clock is applied. It’s widely used in memory storage devices. Here, the given circuit demonstrates the operation of D flip-flop. The flip-flop is built using four 2 input NAND gates, one NOT gate and clock pulse generator is built using multivibrator chip IC NE555. SPDT switch is used to give D input as logic 1 (high – 5 V) and logic 0 (low – 0 V). Different color LEDs are used for input-output logic indications. Please refer the table given below.

SR flip-flop is a short form of set-reset flip-flop. Its output is either set means high (logic 1) or reset means low (logic 0) as per set or reset inputs given. When set input is given logic 1 (high), the flip-flop is set and its Q output is high (another complemented output QBAR will be low) and when reset input is given logic 1, the flip-flop is reset and its Q output is low (QBAR output will be high).In clocked SR flip-flop, the output states will change only when the clock pulse is applied along with S & R inputs. Here, the given circuit demonstrates the operation of clocked SR flip-flop. The flipflop is built using four 2 input NAND gates and clock pulse generator is built using multivibrator chip IC NE555.

The project presented here is very nice, interesting and easy to build. Most of you have seen a multicolor optical light fountain. There is a bunch of pieces of optical fiber cables and multicolor LEDs. The LED light is injected into this optical fiber cable bundle from one side and on the other side, you can see the light coming out that looks like an illuminated dot and this complete structure looks like a multicolor light fountain.In this project, I have replaced the multicolor LEDs with RGB LED and I am controlling this RGB LED through touch sensor using arduino. We know RGB LED can generate most of the colors. So here RGB LED generates three primary (RED, GREEN, BLUE) and three secondary colors (YELLOW, CYAN, MEGANTA) when this different color light passes through optical fiber cables it makes a multicolor light fountain.

LED light is gaining its popularity and replacing all old conventional lights like CFL and other. The most important advantage of LED light is, it consumes very less power and gives very good light. Also LED light operates on DC. So its battery operated, means its portable/mobile. Another very useful feature of LED light is its intensity can be varied. The LED light intensity can be varied and set as per conditions and requirements. To vary the LED light intensity we have to apply PWM – pulse width modulated voltage.

Touch sensor is very popular input device and nowadays widely used as a replacement of push buttons or keys. A touch plate can be used in place of push button or key to providing an input as logic 1 or 0 to the microcontroller. Touch plate (sensor) is conductive material plate or contact that activates when it comes into contact with human body touch.The given project demonstrates how to interface such touch plate with arduino. When a user touches the plate with his finger, the arduino detects this touch and indicates this on LED as well as sends the message on a serial port. Here, the program is written in arduino IDE software and compiled using it. It is uploaded into an internal flash of arduino microcontroller ATMega328 through USB built-in programmer.

Just consider the scenario that you are entering into any suspicious place and suddenly, by mistake, you interrupt an invisible LASER beam and an ALARM or SIREN blows. Nowadays this is a very common scenario. Many people secure their home, office, shops, warehouses, etc with a LASER beam security system. Not only buildings or premises, but many precious things like jewellery, diamonds, precious antique items in the museum, etc many other things are also secured using such invisible LASER beam. In this system, there is an invisible LASER beam that is continuously ON and it is detected by any light sensor. Whenever any object or person comes in between LASER and sensor the beam interrupts and the sensor does not detect LASER light. And that’s ALL!!!! As soon as the beam interrupts (cuts) the siren blows for intruder alert.

You may have seen many projects of generating different colours from RGB LED using Arduino. The given project also generates different colours from RGB LED using Arduino. But also, it displays the amount of red, green and blue colour on LCD. We know, all colours are basically mixing of three primary colours RED, GREEN and BLUE in different amount. For example, by mixing RED and GREEN colour, we can generate YELLOW and by varying their amount we can generate different colours like ORANGE, LEMON GREEN etc many other colours. Also, we can get different shades of RED and GREEN. So here, in this project, I am generating different colours and shades using RGB LED using Arduino and 3 potentiometers. We can vary the intensity of red, green and blue colour of RGB LED by applying variable pulse width input – PWM.

I was doing experiments with arduino UNO and different stepper motors. Surprisingly, I didn’t get satisfactory results. The 3 stepper motors that I have, did not work properly with arduino stepper motor library provided with the arduino IDE software. The problems were: Sometimes they rotate, sometimes don’t; they do not rotate to the exact angle that I want; the RPM (speed) at which motor rotates, that is completely different from what is entered in program; the motor does not rotate to the desired number of rotations or to even specified angle.So, finally, I conclude – the stepper motor library and its functions given is built in arduino IDE, are not compatible with all kind of stepper motors – especially unipolar stepper motors. I decided to create a universal kind of arduino library for all unipolar stepper motors.

Here I present Arduino library to control DC motor. The library is having so many facilities and flexibilities that it can control any DC motor in required manner. The library is designed as per the industrial motion control requirements. The library is having 16 different functionalities such that it can control the motor in most versatile manner. Here is the list of facilities in library.Here is the list of facilities in library: It controls direction of rotation of motor, it controls speed of motor from 0-100%, it can provide soft start to motor in specified time – means motor speed will increase from 0% to desire level in specified time, it can provide smooth stop to motor in specified time – means motor speed will decrease from current speed to 0% in specified time, it can apply jog control to motor in either direction – means motor will jerk in specified direction, and it can apply DC BREAK  (means immediate or emergency STOP) to motorHere is the list of facilities in library.

Here, I present 3-in-1 parameter monitoring system that measures and displays- Current temperature (in oC ), Humidity (RH in %), Light intensity (in %). The interesting thing is it has digital cum analog meter consol. Means values are displayed on LCD as a digital read out as well as they are indicated on retro-style analog dial (scale). All three parameters are measured one by one and they are displayed on LCD as well as on analog dial after some delay. It continuously monitors all three parameters and displays them turn by turn on both meters.The project is build using Arduino UNO board with DHT sensor (to measure temperature and humidity), LDR (to measure light intensity) and LCD. It uses servo motor as a pointer to indicate value on analog meter.

I bought wired remote controlled car for my little princess. Using wired remote it can move forward and reverse. It was very simple toy car with a DC motor inside and in remote, there were two AAA size battery cells with two buttons – one to move the motor forward and another to move reverse. It was working very fine and the car runs very nice. But once, my baby broke the remote.I tried to repair it but the button’s contacts were broken so it was not possible to repair it. The remote can be built using one DPDT switch, one sliding switch and 3 AAA size batteries. DPDT switch is as shown in the given figure with its internal connections. It has 6 terminals and it is used to move the car forward and reverse.