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Capacitors: Capacitor is also called as Condenser in electronic circuits. The characteristics of a capacitor is measured in terms of Capacitance, which is the Quantity of Charge stored in a capacitor. The units of Capacitance is Farads in S.I. system. One unit of Farad is very high for all practical purposes. So, microfarads , nanofarads , picofadas are used in the circuits. Capacitance: A capacitor contains two electrical conductos separated by a dielectric medium. Conductor of a capacitor may be a thin metallic foil or thin metal bead or an electrolyte. The nonconducting dielectric commonly used may be glass or ceramic or plastic film or paper or mica, air etc. The capacity of Capacitor increases with decrease in the gap between the conductors and increase of the area of conductors Fixed value Disc Capacitors: Some disc capacitors are marked their capacitance in pico Farads (pF) in three digit coded form. The first two digits indicates value and third digit indicates number of zeroes followed. Refer examples shown below. Fixed or Disc Capacitor does not have any polarity. The two pins may be connected to either positive and negative lines of the power supply or electronic signal. The capacitance value or code is printed on its surface. Maximum voltage it withstands are printed on some capacitors. The maximum value of these capacitors are 1 micro Farad and are available in lower fractions like nano Farads and Pico Farads Fixed value Polarized Capacitors: Polarized Capacitor contains negative terminal marked on its surface. i.e., a black band with negative (-) symbol. For new capacitors the negative terminal is kept shorter than positive terminal. These are mostly electrolytic (conducting material) capacitors. ​ The capacitance of these capacitors are normally starts from 1 micro Farad and available up to 10,000 micro Farads. The capacitance value and maximum voltage it withstands are printed on its surface. ​ Care should be taken while connecting a Polarized Capacitor to avoid damage. i.e. positive terminal of capacitor should be connected to positive supply line and negative terminal of capacitor should be connected to negative supply line only. Variable value Capacitors: Variable Capacitor can vary its capacitance by changing the conductor area by moving the conducting plates, normally by rotation. These capacitors normally have air as dielectric medium and its capacitance ranges in pico Farads. A tank circuit shown here, contains a capacitor and an inductor (coil) which generates frequency depending on the values of capacitance and inductance. A transistor is used to maintain the frequency with proper amplitude. These capacitors are mainly used in tank circuits, which generates oscillations and are used in radio (high frequency) circuits, for tuning the required frequency. Capacitors in DC circuits: Capacitors in DC circuits: Capacitors are used as temporary storage medium in DC (Direct Current) circuits. But, the charge across the conductors leaks through the dielectric medium after sometime. The leakage is high initially and slows down after some time. ​ A capacitor is used as filter in rectifier circuits to reduce the ripples of unregulated voltage, there by generate study voltage. Initially a capacitor charges quickly then slows down the charging rate and matches to the source voltage (i.e., saturation level). Similarly, on discharge, the discharge rate is very high initially, then slows down and reaches to zero level (total discharge). Capacitors in AC circuits: Capacitor in AC circuits behaves differently than DC circuits. A change in voltage on conductor of one side of the capacitor effects on conductor of other side of the capacitor. The output signal is reversed to the input signal polarity. So, AC signal will be transferred in series using capacitor where as DC component will be blocked across the capacitor. High frequencies and/or high capacitance makes easy passage of AC signal through the capacitor. The resistance offered in AC signal across a capacitor is called Impedence marked as Z . So, DC is considered as lowest frequency (almost zero frequency), therefore, the Impedence is highest (tends infinity) for DC signal. Capacitors in PARALLEL connection: If multiple Capacitors are connected in parallel in electronic circuits, the resultant capacitance is equal to sum of each capacitance in the circuit. So, the Resultant Capacitance is always more than any capacitance in parallel connection in the circuit. Capacitors in SERIES connection: If multiple capacitors are connected in series in a circuit, the resultant capacitance depends on the gap between the conductors of each capacitor. So, the Resultant gap is equal to sum of gaps between each capacitor in series. So, in terms of capacitance, inverse resultant capacitance is equal to sum of inverse capacitance of each capacitor in series. The Resultant Capacitance is always less than any capacitance value of any capacitor in the series connection in the circuit. SUPER CAPACITORS: Super Capacitor is a capacitor with high-capacitance than electrolytic capacitor. It works as a low time storage battery. But, its storage voltage (normally available up to 5V) is very less comparative to normal capacitor. ​ The units used for Super Capacitors are in Farads and normally available in 1Farad or more.

microcontroller - COMMUNICATIONS Micro controller Communication means, communicating the internal data or status of a micro controller to external world through its pins as voltage or reading the voltage from its external pins and saving it its registers for further processing as per its program. The communication happens so many ways with micro-controller. We will discuss the concepts of micro controller communication one-by-one. ​ All the Communcation process, values and direction is dependent on the bit(s) set in the related registers of the micro-controller. These bit(s) may be varied by the program code as per your requirement. Analog Communication: In micro controllers, using Analog comminication is limited. But, the human world works on analog values, the micro controllers are provided with ADC (Analog to Digital Converter) and DAC (Digital to Analog Converter) features. ​ The ADC converts the analog value (input voltage) to suiable digital form and saves in its registers for further processing as per the program. ​ The DAC converts the digital value set in its register to suiable analog value (output voltage) for further external equipment control or display. ​ The processing and features about ADC/DAC are discussed seperately and press here for ADC/DAC concepts. Digital Communication : ​ The digital communication mainly works on logic 0 and logic 1 as either input or output. Normally voltage level towards ground level or zero volts is considered as Logic 0. Where as for Logic 1, voltage towards 5VDC as TTL (Transistor Transistor Logic) or some times 3.3V or Vcc are considered for most of the micro controllers. ​ One or multi bit Status: The highly used coomunication is one or more bit(s) status input or output. This is achieved by setting the required bits in the data direction register(s). By setting 1 or 0 in the data direction register, the pins connected to the register, reads input logic from the specified pin or sends output logic to the specified pin. Generally, any pin may be programmed as input or output pin, except for special purpose pins indicated in the data sheet(s). ​ This communication is useful to read one or more button status or status from other electronic equipment or drive one or more LEDs or any other digital devices like displays etc. Parallel Data Communication : The parallel communication is reading or writing a number of data bits simultaneously. Normally, EIGHT number of bits (named as BYTE, identified using ASCII) are used for transmission. Normally, a clock pulse is also sent with the 8 bit data to validate the data on transmission. ​ Serial Data Communication: Serial Communication is highly used in micro-controller projects. The main advantage with Serial Communication is, it uses less number of conductors (wires) for data transmission when compared to parallel data communication and long distance data transmission is also possible with serial communication. ​ The main disadvantage with the serial communication is all the data bits has to be transmitted through single wire sequentially, which takes much time compared to parallel data transmission. ​ Univeral Serial Data Communication: USART (Universal Synchronuous Asynchronous Receiver and Transmitter) or UART (Universal Asynchronous Receiver and Transmitter) are common and Universal serial data communication method used in most of the micro-controllers. ​ The parallel data is converted to serial bits and transmitted through Transmitter pin or the serial data is received from Receiver pin and converted to parallel data in USART/UART communication. ​ In synchronous method, a clock is generated by the master processor and slave(s) transimit or receive the serial data using the clock. Where as in Asynchronous method, all the processors generate their own clock matching to same frequency and data is transmitted and received using their clock frequency by eliminating the transimission of clock connection to all the processors. ​ The registers in the micro-controllers may be set for Full-Duplex (Transmit or Receive simultaneously) or Half-Duplex ( Only Transmit or Receive at-a-time) or Simplex (Uni-direction, either Transmit or Receive) as per the requirement and feature(s) supported by the micro-controller. ​ The USART/UART communication is normally used to connect to PC (personal Computer) through COM port using Voltage level managing board as interface. ​ SPI Communication: ​ SPI (Serial Peripheral Interface ) uses three wires for communication (MOSI MISO and SCK). The data direction will be controlled by the master processor, which also generates clock pulses for accuracy of communication. The slave processor on the other hand communcates with the master synchronising the clock from the master. This is a full-duplex (two way) stable communication. MOSI = Master Out Slave In, means data is transferred from master to slave processor. MISO = Master In Slave Out, means data is transferred from slave to master processor. SCK = Serial Clock, is generated by the master processor for stable and accurate communication SS = Slave Select, the slave select pin for selecting as master or slave using hardware or software. A single master processor may be connected to multiple slaves and control them selecting the SS pin of slave processor. ​ Two Wire Communication: ​ Most of the micro controllers support the Two Wire communication, which is well known as Inter Integrated Circuit or TWI or IIC or I2C (pronouced as I squared C ) communication. Only two wires (SDA and SCK ) are used for communication with multiple devices like micro-controllers, sensors , EEPROMs, ADC ICs, DAC ICs and other ICs which support IIC. ​ All the devices will be connected to the same bus (two wires) and identified by their IDs marked inside the chip by hardware or software. A standard protocal will be followed to access / communicate with each device using master and slave concept. ​ The ICs marked as slave works as slave only, where as other ICs and micro-controllers may work as either master or slave as per its programming. ​ Univeral Serial Bus (USB) Communication: ​ Some micro-controllers support USB communcation, which is very useful for data transfer or data backup from / to devices like pen-drives and connecting external gadgets like keyboard/mouse etc. ​ Four wires are used from USB connection. Two wires are for power supply (+5V and Ground) and Two wires for Data transmission (D+ and D-). So, the micro controller which supports USB marked with D+ and D- pins. ​ Various data transmission speeds are available, for USB data transfer, depending on the versions. They are Low speed 1.5Mbps or Full speed 12Mbps in USB version 1; High speed 480 Mbps in USB version 2; more than 4.8 Mbps and upto 6Mbps in USB version 3. ​ Most of the micro-controllers support USB version 1 speeds only which are useful HID ( Human Interfac Devices ) interfacing, like keyboard, mouse, sensors etc. ​ All the USB devices uses standand individual protocols. The micro-controller used in a project has to support and communicate with the devices using the proper protocols. ​ SUMMARY: ​ The type of communication is used based on the requirement , speed and type of interface avaialble on the sensor / device, that is to be controlled or communicated. The micro-controller has to be selected accordingly. GOOD LUCK TO YOU.

Transformers A transformer works on mutual inductance using AC (Alternating Current) power supply as input to step-up or step-down the output voltage. The input and output coils for mutual inductance are normally connected by a soft iron core. Basics of Transformer: A transformer mainly consists of a core made up of steel laminations for magnetic connection between two coils . Where as, a coil is considered as multiple insulated conducting wires (generally made of copper) wound on the ferrous core. Out of two coils, the coil, which is connected to input AC power supply is called as Primary coil and the other coil, which is generating the AC power due to mutual inductance is called Secondary Coil . Transformers are available with various types of constructions. Various shapes of ferrous cores are designed for least leakage of magnetic flux. The ferrous core is generally made of laminated sheets with insulation in between them to have least eddy current losses. Ferrite core is used for high permeability, which is required, when the frequency of AC input power supply is high. Some times both primary and secondary coils are wound one on another with high electrical insulation in between them. Basic Transformer Formulae: For any transformer, the total power conversion is constant, which mainly depends on the primary coil, secondary coil and core. ​ So, theoretically, Input Power = Output Power, ignoring winding losses, eddy current losses etc. i.e., Vin X Iin = Vout X Iout considering all losses together, the efficiency of transformer is ratio of Output power to Input Power, which varies from 80% to 95% approximately. ​ Similarly, the output voltage depends on the input voltage and ratio of number turns of secondary coil to primary coil. i.e., Output Voltage / Number of Secondary turns = Input Voltage / Number of Primary turns Vout / Nout = Vin / Nin or in other words, Vsecondary / Vprimary = Nsecondary / Nprimary The above ratio is called Transformer ratio or Transformation ratio , which is denoted by r . The main points to be notes for a transformer are , 1 ) It works on AC (Alternating Current) power supply only. 2) It works on mutual inductance between two coils (input and output). 3) A Ferrous (or Ferrite) core is used as a medium to transfer magnetic connection between the two coils. 4) The two coils are electrically isolated from each other 5) The output voltage and current depends on input voltage, current and number of turns of primary and secondary coils. Types of Transformers: So many Varieties of transformers are used, depending on the necessity of output, core type, cooling system etc. Some of the types are listed below. 1) Step-Down Transformers: Step-down transformers are highly used in electrical and electronic circuits. A step-down transformer reduces (steps-down) the output voltage w.r.t. input voltage. i.e., The output voltage available at secondary coil is less than the voltage available at primary coil. As the total power of a transformer is fixed, the current in output (i.e., at secondary coil) increases. ​ A Step-down transformer ( mains AC supply to 9VAC) is shown here, which is normally used in electronic circuits. 2) Step-Up Transformers: Step-up transformers are used, when more output AC voltage is required, w.r.t. input AC voltage. So, the output voltage available at secondary coil is more than the input voltage applied at primary coil. ​ As the total power of a transformer is fixed, the current in output (i.e., at secondary coil) decreases w.r.t. input current. 3) Multiple Voltage Output Transformers: Some transformers have single primary (input) coil and multiple secondary (output) coils. The output coils may not have interconnection to have separate and individual voltages or connected in series. Most of the transformers used in electronics circuits are center tapped transformers. These transformers are used in power supplies for single or different circuit boards, with various required voltages, from mains. 4) Constant Output Voltage Transformers: Some transformers have multiple input connections on primary coil and single (or sometimes more) secondary coil as output. The input tappings are manipulated using a circuit to have fixed output voltage. This type of transformers are normally used in stabilizers, to have fixed AC output voltage, when AC input voltage is fluctuating. 5) Variable Output Transformers: The Variable transformer have single coil wound on a ferrous core. The input power supply is connected across the coil at a suitable number of turns. The output voltage is obtained by having movable tapping point on the coil (using a spring loaded brush). ​ As the Ferrous core is in a circular shape, the movable brush contact is rotating, which is connected by arm to the central axis of the circular core. So, the output voltage is obtained based on the number turns contacted to movable brush, by rotating the central shaft. Transformer Cooling: The transformers used for low power, which are normally step-down transformers, used for power supply to electronics circuits are air cooled. ​ For the transformers used for high power and continuous duty cycle are oil cooled, where the transformer core and coils are submerged in an insulated oil in an enclosure. The oil in the enclosure, gets circulated to atmosphere for heat transfer.

Small Robot : 4 IR Remote Control # . < < < Previous List All Next > > > . Introduction Another way to control the Small Robot is, using an IR (infra Red) remote. Here, a handy remote with direction markings is selected for controlling the Small Robot. The IR remote sends a specific pattern of digital signal through its IR LED, based on the button press. An IR receiver module (TSOP 1738) receives the IR signal from the IR remote and sends to the micro-controller (ATTINY13). Then, the micro-controller decodes the signal and converts it to 4 bit binary code, which is available as D0,D1,D2 & D3 at 6 pin connector. Then, the 4 bit code is received by the motor driver IC (L293D) on the Base Frame, to drive the two B.O. motors accordingly. (refer Small-Robot Base Frame for motor control codes) A small 8 pin micro-controller (ATTINY13) is used in Receiver circuit. As the transmitter is IR remote, so there is no need of Transmitter board and micro-controller. Any IR remote may be used to control the Small Robot. But, the signal generated by the IR remote should be decoded and then it shall be converted to, required 4 bit binary code, to control the Small Robot. Similarly, any IR receiver with 38KHz carrier frequency may be used, like TSOP1838, TSOP98138, TSOP38328, TSPO38438 etc. The pinouts should match with the circuit. IR (Infra Red) Transmitter: The IR remote used in the project is clone to Panasonic Audio remote control, which is easily available at affordable price (The original Panasonic remote is costly and not advisable for our project). The main advantage with this IR remote is, it has the four direction keys on a handy size. The front two buttons used for volume control are used to rotate the Small Robot in Clockwise and Counter-Clockwise directions. Most of the IR remotes use 38 KHz carrier frequency. It means, the IR LED of the remote glows on/off for 38000 times per second, which is called as Carrier Frequency. Again, the time of 38 KHz IR LED frequency varies for code generation. Say, to send a digital code '1' , the 38 KHz frequency is available for more time, compared to send code '0', before stopping the Carrier Frequency. So, a specific pattern of digital code is sent by the IR remote, on each key press. To differentiate or identify the IR code from each IR remote manufacturer, a header code is sent initially and the digital time also varies. (The header code ignored in our case). IR (Infra Red) Receiver: In the IR Receiver Board, the IR receiver, TSOP1738, is used, for easy identification of its pin-outs. One of its pin, out of 4 pins, is absent, which makes the pin identification fool proof. (Refer the circuit diagram below for better understanding). So, the Infra-red signals received by the IR receiver, TSOP1738, filters the Carrier Frequency and sends the digital code to the micro-controller (ATTINY13). An LED is provided to show the status of data reception from the IR receiver. The micro-controller decodes the received data, and converts to four bit parallel data. Then the four bits are sent to the base frame through the 6 pin connector, which in turn controls the movement of the Small Robot. In case, to use different remote, the IR pattern has to be studied and the Source code is to be modified accordingly (modify the getIRcode() function as required). The 5VDC power supply for Receiver board is derived from the Main board of Base Frame, through 6 pin connector. Good Luck Download IR HEX file Contact for Source Code Download file from above link and remove .TXT extension. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .

Small Robot : 1 Base Frame # . < < < Previous List All Next > > > . Introduction The following are the General Requirements of a basic robot: 1. Chassis – 1no. 2. Motors – 2nos 3. Wheels – 2nos 4. Castor wheel – 1no 5. Battery and power supply circuit – 1 no. 6. Motor driver – 1no. 7. Controller Board (Microcontroller or other) – 1no (minimum) 8. Display / status indicators – as per requirement 9. Sensors / other input devices – as per requirement 10. Programmer (to load code to microcontroller) – 1no. 11. Software(s) – as per requirement. 12. logic development skills. Out of above listed 12 points, first 6 points are common and hardly change the items. These are mainly hardware items and does not require any software skills. Same robot can be modified to required configuration by changing micro-controller / sensors / inputs / displays / software / logic. The Small Robot is simple in construction, compact design and have mainly two parts. The first part , Palm Robot – Base Frame, contains the 1 to 6 items of the above list and second part, Small Robot – Control, contains the 7 to 12 items of the above list. By using Small Robot Base Frame, time is saved to develop logic using various micro-controller(s) and software(s). The Small Robot control systems are designed/developed using AVR microcontrollers here. But, the same logic can be developed using PIC or other microcontroller(s) and the output of the logic can be used to control the Small Robot Base Frame. About Base Frame: The Small Robot – Base Frame, contains two B.O. motors with 200 rpm are attached to a chassis on either side and two suitable wheels are mounted on it. A castor wheel with bracket is fixed on front side of the chassis. A 7.4V Li-ion battery is placed between two B.O.motors. 4 or 6 nos of long bolts may be suitably arranged on top of the chassis to hold circuit boards. A circuit board, called Main Board, with motor driver IC (L293D) and two separate 5VDC regulated power supplies are fixed on top of the chassis, which hardly covers half of the chassis and makes room for adding microcontroller board of one’s choice. One of the 5VDC supply may be used for microcontroller board and sensors. The other 5VDC supply or 7.4VDC from the battery may be used for motors by selecting jumper J1. Due to separate 5VDC supplies, the microcontroller board have least impact of voltage fluctuations due to motors. A six pin berg strip is available on the Main Board. Out of 6 pins 2 pins are Ground and 5VDC supply for Microcontroller board and remaining 4 pins are data input pins (D3, D2, D1, D0) for motor control. The logic for control of motors are as follows: Circuit Diagram of Main Board A PCB is required to assemble all the components shown below in the circuit diagram. For Small Robot, the PCB is fitted on the top of the chassis, where as motors (with wheels), castor wheel and battery is fitted below the chassis. Good Day to you Download 4 bit code Contact for Source Code Making Base Frame is mandatory to add various types of controls. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .

Slim-Bot 4 Wireless Keypad Control Introduction .. As the name indicates, SLIM-BOT, is a small, simple, compact robot, which may be moved or controlled using various inputs, without using any micro-controller. There is no need of programming language or coding to make and control the Slim-Bot. This is the basic project for those, who don’t have any knowledge in micro-controllers and programming. The various controls for the Slim-Bot is completely based on the electronic circuits only. A robot may be controlled wirelessly in many ways. Here, the Slim-Bot is wirelessly controlled using a 4 button keypad. Four buttons are used as input system to control the movement of the Slim-Bot, which generates 4 bit code. Then the code is encoded using an Encoder IC (HT12E) and outputs the code in serial format. Then the serial output of the encoder is transmitted by an RF transmitter. The serial data is received by the RF receiver and send the data to Decoder IC (HT12D). The Decoder IC, decodes the received serial data, back in to 4 bit data. The 4 bit data is used to control the movement of the Slim-Bot. About Keypad Transmitter: For simplicity and easy understanding of working of a keypad, a simple four direction keypad is made here. Four numbers of two pin tactile button switches are arranged in North-South-East-West (for Forward-Backward-Right Turn-Left Turn movements respectively) format and the connected as shown below. The Backward, Right turn and Left Turn button press signals are directly fed to the Encoder IC (HT12E). Whereas for Forward movement, two diodes are connected from North button, to right and left buttons, to have movement of both right and left motors forward, thus the Slim-Bot moves forward. The Encoder IC, HT12E, has 12 inputs, i.e., 8 address pins A0 to A7 and 4 data pins AD8 to AD11 . All the 8 address pins are internally connected to logic high. To make a specific 8 bit address (or code to select matching Decoder IC, HT12D), required pins may be connected to ground. Here, all the pins are left open to get address as 11111111 binary code (= FF hexadecimal). The TE pin (pin 14), Transmit Enable, is connected to ground for continuous transmission of the button code. The 4 bit button press code is fed to AD8 to AD11 pins of Encoder IC, HT12E, and the encoder generates, a serial data at Dout pin (pin 17), which contains the 8 bit address code and 4 bit data code sequentially. The serial data is then sent to an RF (Radio Frequency) module. You may use either 433MHz or 315MHz RF module for the purpose. A good antenna increases transmission range of radio frequency. About Receiver Board: The radio frequency is received by an RF receiver module (should match the RF transmitter frequency 433MHz or 315MHz), and the 12 bit serial code is sent to Din pin of Decoder IC, HT12D. Similar to the Encoder IC, the Decoder IC (HT12D) also has 8 bit address pins (A0 to A7) and 4 bit data pins (AD8 to AD11) . The 8 bit address pins of decoder IC, shall match the address code pattern of the encoder IC, i.e., the same pins of decoder IC should be connected to ground, matching to encoder IC. Then, the 4 bit data is available at AD8 to AD11 pins of Decoder IC. The VT pin (Valid Transmission) goes high, whenever the received data is matching to the set address pattern at A0 to A7 pins. As the 8 address pins of Encoder IC are left open (not connected to ground) for the transmitter, here also the 8 address pins of Decoder IC are left open, to match the address, i.e., binary code = 11111111 (= FF hexadecimal). So, the 4 bit signal data available at AD8 to AD11 pins are connected to the D0 to D3 pins of base board on Slim-Bot as shown below, to control the movement of the Slim-Bot. Here, the Decoder IC and RF receiver module may be directly soldered on the Base Board (PCB) of the Slim-Bot, or soldered on a separate board, then insert in to the 8 pin berg-strip available on the Base Board. A separate 3.7V Li-Ion battery may be used for the power supply of Decoder IC and RF module, to reduce interference to RF signals and isolate from the motors power supply. Additional battery is connected between the Vcc and ground, through a switch in series as shown in the circuit and the shorting jumper shall be disconnected on the base board. CLICK HERE to know, how to make BASE for SLIM-BOT .

Swift IR Sensor / Remote Tester Now-a-days almost all electrical and electronic gadgets are opereated by IR remotes, which uses 38 KHz carrier waves to transmit the code using IR (InfraRed) waves, which is invisible to naked eye. The Swift IR Tester project is useful to test your IR remote quickly and you may test the IR sensor before soldering to the PCB of your new project. This Swift IR Tester is also useful to study the code generated by the IR remote. Many types of IR sensor are available in the market with various pin outs. Four types of IR sensors with their pin outs are shown here as quick reference. All the four types of IR sensors may be tested in our circuit, with proper insertion of pins in to the berg strip provided for testing. (Courtesy:Vishay) The maximum Power supply for almost all TSOP sensors are 5.5VDC with a series resistance and decoupling capacitor near the sensor to filter the noise signals. The TSOP package contains a regular IR sensor with 38 KHz (some models vary the frequency) filter circuit. The IR remotes send IR light with 38 KHz as carrier waves. A code is sent by switching ON/OFF the 38 KHz frequency for particular time. The IR code receiver de-codes the ON/OFF signal through the IR sensor and send the code for controlling the gadget. The circuit used for Testing IR sensor and IR remote is simple and full circuit diagram is shown here. For comfortable use of the circuit, place the berg strip (with holes) on one side of the PCB and USB plug on the other side. The unused (NC) holes in the berg strip may be closed / blocked for easy identifacation of pins and fool-proof insertion of the IR sensor. Better to mark Vs (red colour) and GND ( blue/black colour) connections near to berg strip. ​ Once the circuit is made on a small PCB, insert an IR sensor, in such a way that, the pin outs should match the markings on the PCB (Vs, GND and OUT). Connect shorting jumper J1 in position. Then, switch ON the power from 9V battery else insert the circuit in any USB port, normally available with power banks, personal computers, laptops etc. ​ Now, select any IR remote available in your home and press any button on the remote. The Red LED blinks in response to the IR remote code. You may quickly check any IR remote or IR sensor with this circuit. You may also use this circuit to study the code received from the IR remote using 3 pins 5V, GND and OUT. ​ That's ALL. ENJOY

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displays Displays are used to show the output of a process or status of equipment or monitoring the status of the process. LEDs: The simplest display used in an electronic equipment is two lead LED , one for anode(+ve) and another for cathode(-ve). The LED indicator is simplest and cheapest display system for monitoring the process, available in multiple colours, which makes the display of status more easier. The LEDs works between 1.8 VDC to 3.5VDC, which depends on emitting colour and manufacturer . The current capacity depends on its size (in diameter) and wattage. for more description on LEDs click here Seven Segment LED Displays: Next comes the Seven Segment Display, which is a rectangular block having seven long rectangular LEDs in 8 format. The Seven segment display is normally used to show numerics from 0 to 9 by switching ON and OFF particular LEDs. Sometimes some Alphabet are also displayed using Seven Segment Display. Connecting pins for each LED (segment) are available at the back side of the Seven Segment Display, with one or two common pins for all seven segments. The common pin may be connected to positive (or negative) DC power supply and other pins of seven segments may be connected to negative (or positive). For Common Anode (CA) Seven Segment Display, the common pin(s) should be connected to Positive DC power supply and each segment pin should be connected to negative power supply to glow the particular segment (or LED). Similarly, for Common Cathode (CC) Seven Segment Display, the common pin(s) should be connected to Negative DC power supply and each segment pin should be connected to positive power supply to glow the particular segment (or LED). In general, Seven Segment Displays may glow in Red or Green colour in various sizes like 0.5", 1", 2.5", 4" etc. Now-a-days Seven Segment Displays are available in RGB colours also. All the Seven Segments are named as a, b, c, d, e, f, g and one more pin is used to glow dot on the right bottom side of the rectangle. The pin connections depends on the model , size and manufacturer. Connections and identification of seven segment are shown here for Seven Segment Display with top and bottom pins. The seven segment displays are also available in multiple displays in one block. This will reduce the wiring and number of pins to control the display. For continuous display, each segment of particular display has to be selected sequentially, which may be managed by a micro-controller. ​ A 4-in-1 seven segment block is shown here. similarly, 2-in-1 and 3-in-1 are also available. Sixteen Segment Alpha-Numeric LED Display: The 16 Segment LED display is similar to Seven Segment Display, except it can display all Alphabets and Numerics. ​ The main difference is, the three horizontal segments ( a, g and d ) are made in two parts , two vertical and four inclined segments are added in between. LED Bar Graph: LED Bar Graph is a rectangular block with 10 number of LEDs arranged in a row. The connecting pins (10 anode + 10 cathode) are available at the back side of the block as shown in the figure. They are available in Red or Green or Blue or Yellow or Amber or R G B colored LEDs LED Matrix Array: 64 LEDs are arranged in 8 X 8 matrix format in a square block. By selecting pins at the back side of the block, required LEDs in combination of 8 rows and 8 columns may glow. ​ The LEDs may glow in Red or Green or Blue colour. Now-a-days, RGB colours are also available. In this case, each LED may glow in combination of colours. So, the LED matrix is very useful to display pictures or graphical output. ​ It is very difficult to select each LED out of 64 LEDs. So a separate display controller IC (MAX7219) is used for the purpose. The IC has serial data input and serial data output pins, which may controlled by a micro-controller. ​ A display module with the IC (MAX7219) is readily available in the market. Some modules have two or four display blocks on single PCB and simple serial data control system. Any number of LED matrix modules may be connected in series and are to be controlled by a micro-controller (or similar circuit). ​ A readily available 4-in-1 LED matrix module is shown here, which has input pins one side and output pins on another side to connect further / next modules in series. LCDs: The LCD (Liquid Crystal Display) is highly used text display in micro-controller projects, which is cheaper and easily available. The text may be displayed in the following ranges: ​ 1 Row x 16 Columns 2 Rows x 16 Columns 4 Rows x 16 Columns 4 Rows x 20 Columns ​ The LCD may controlled by 16 pins. The data may be sent by 8 bit (byte) or 4 bit (nibble), which should be selected by sending specific codes after power on. The contrast of the display is controlled at pin-3 of LCD, through a trim-pot connected between 5VDC and ground. GLCDs: The GLCD (Graphical Liquid Crystal Display) has good viewing size of pixel size (0.48mm x 0.48 mm) and screen area (66mm X33mm approx.). The screen is logically divided into two panes as 64X64 pixels on left side and 64X64 pixels on right side, which makes 128X64 pixels in total. The left side pane is selected using CS1 pin and similarly right side pane is selected using CS2 pin. The data and command to GLCD is transmitted in 8 bit format by selecting RS pin setting high/low. The contrast of the display is controlled at pin-3 of GLCD, through a trim-pot connected between -10VDC ( available at pin 18 of GLCD) and ground. OLEDs: OLED ( Organic Light Emitting Diode ) is available in very small size with graphical display support, which consumes very less power and displays sharp image. ​ The input pins contains either I2C (TWI) or SPI (or both) interface with two power supply pins. The display size and display colour(s) varies as per specification. The OLED shown here are highly used in the DIY projects. TFT Displays: TFT-LCD (Thin Film Transistor Liquid Crystal Display) has smaller and sharper pixel than normal LCD display and consumes lesser power. TFT-LCD can display an image or text in colour. Some TFT-LCD modules have touch sensitivity with stylus and/or Micro-SD card slot. Most of the small size (upto 3.5 inch) TFT-LCD modules have pins, which are compatible (suitable) for Arduino Uno / Arduino Meaga boards. The higher sized TFT-LCD modules may have various signal input pins and slots like, USB, VGA, HDMI etc. Other display systems like AMOLED (Active-Matrix Organic Light-Emitting Diode), SAMOLED (Super Active-Matrix Organic Light-Emitting Diode), QLED (Quantum dot Light Emitting Diode) are new technologies emerging in the market. But, proper interfacing system for DIY is not available right now. In future, some more new technologies in display system is expected with high quality and low power consumption at affordable price.

Slim-Bot 6 Wireless 5D Rocker Control Introduction .. As the name indicates, SLIM-BOT, is a small, simple, compact robot, which may be moved or controlled using various inputs, without using any micro-controller. There is no need of programming language or coding to make and control the Slim-Bot. This is the basic project for those, who don’t have any knowledge in micro-controllers and programming. The various controls for the Slim-Bot is completely based on the electronic circuits only. Now, the Slim-Bot may be controlled wirelessly, using simple and easy control with 5D (Five Degrees of Freedom) Rocker Joystick. A 5D Rocker Joystick module has a small knob to control in all the five directions (Up-Down-Right-Left-Mid) along with two button switches (Set and Reset), which is easier for manoeuvering the Slim-Bot than Analog Joystick. All the outputs of 5D Rocker Joystick are digital. So, the control circuit becomes simpler compared to analog Joystick. So, the digital values are directly fed to Encoder IC (HT12E) and then transmitted wirelessly using RF transmitter. The serial data is received by the RF receiver, which sends it, to Decoder IC (HT12D). The Decoder IC, decodes the received serial data, back in to 4 bit data. The 4 bit data is used to control the movement of the Slim-Bot. About 5D Rocker Transmitter: The 5D Rocker Joystick module used here is easily available in the market, which has a berg strip as connecting pins. The 5D Rocker Joystick module contains a common input pin (COM), with seven digital output pins, viz., Up, Down, Left, Right, Middle, Set and Reset. When the knob is moved horizontally (left or right), the button switches on left or right side of the knob gets connected to COM pin, and pins LFT or RHT are connected to COM pin. Similarly, when the knob is moved vertically (up or down), the pins UP or DWN are connected to COM pin. In case the knob is pressed down or set or reset button is pressed down, then the COM pin is connected to MID or SET or RST pins respectively. So, when the COM pin of 5D Rocker Joystick module is connected to DC power supply (or match to circuit power supply voltage), and turning the knob or pressing each button switch (using rocker knob), the voltage appears at one of the pins UP, DWN, LFT, RHT, MID, SET and RST accordingly. It means the particular pin goes logic HIGH with corresponding operation of the knob or pressing the specific button switch. Here, the UP, DWN, LFT and RHT pins are connected to the Encoder IC (HT12E), with two diodes as explained in the Wireless Keypad Control. Then the digital code is encoded by the Encoder IC (HT12E), which outputs the code in serial format. Then the serial output of the encoder is transmitted by an RF transmitter. The connections between 5D Rocker Joystick to Encoder IC (HT12E), then to the RF transmitter module, are shown in the circuit diagram below. ( CLICK HERE to know more about working of HT12E and RF transmitter, from wireless keypad control) About Receiver Board: There is NO CHANGE in Receiver Board or Slim-Bot, w.r.t. Keypad Control system. Once the Transmitter module is ready, then switch ON the power supply to Transmitter and Slim-Bot for easy control of Slim-Bot using 5D Rocker Joystick. The Receiver circuit diagram is shown below. Refer KEYPAD CONTROL SYSTEM , for more explanation about Receiver circuit. CLICK HERE to know, how to make BASE for SLIM-BOT.

Small Robot : 8 Edge Detector # . < < < Previous List All Next > > > . Introduction: An Edge Detector is also a self controlled Robot, which will recognize edge of a flat surface (like table) and moves within the flat surface, without falling down. Two IR sensor modules are used on front side of the Small Robot to recognize the edge of a surface. The two IR sensors on both sides, read the presence of the flat surface and the signal is sent to the micro-controller (ATTINY84) accordingly. The signals received from the IR sensor modules are analyzed by the ATTINY84, then Small Robot moves back a little and takes right or left turn accordingly, based on the 4 bit motor control data, through the motor driver (L293D) on base board. (refer Small Robot Base Frame for motor control codes). The concept of Edge Detector Robot is to avoid falling from edge of any flat surface. The Edge Detector searches for the reflection of IR light from the bottom surface, then moves forward or takes turn accordingly, to avoid falling from the flat surface. Here, the Small Robot is programmed to take a right or left turn, when the IR light reflection is absent, depending on the IR sensor module signal, else moves forward continuously. About Edge Sensing: The Edge Detector uses two IR (Infra-red) sensor modules (readily available) to read the presence of bottom surface. The IR sensor module consists of an IR emitting LED , an IR sensor LED, indication LEDs and an OP-AMP IC (mostly LM358), with a trimpot for sensitivity adjustment. When the module is connected to 5VDC power supply, the IR LED emits IR light on the bottom surface. The IR light reflected from the bottom surface and falls on an IR sensor (in LED shape), placed near to the IR LED. The op-amp based circuit, reads the change in the internal resistance of the IR sensor, due to IR light falling on it, and status is displayed by glowing indicator LED (red). When the reflected IR light is absent, then the indicator LED does not glow (status off). A three pin connector is available on IR sensor board, out of which two are for 5VDC and ground. The third pin is signal OUT pin. So, when the surface below the IR sensor is present, then a HIGH (1) signal is generated at OUT pin. Similarly, when the surface is absent, then a LOW (zero) signal is generated at OUT pin. The LED indicator glows accordingly. After assembly, adjust the trimpots on the IR sensor boards, independently, for their sensitivity to surface reflection. The arrangement of two numbers of IR sensor boards are show below. Both the IR sensor boards are to be fitted on front side of the Small Robot, on either side. The distance between the two extreme IR sensors shall be kept more than the overall width of the Small Robot. Working of Edge Detector: Making of Small Robot as Edge Detector is simple and easy. A simple bracket is required to position two IR sensor boards on the front side of the Edge Detector. A PCB with micro-controller ATTINY84 is used as control system for the Edge Detector, based on the digital signals (at OUT pins) available from two IR sensor boards. The digital signals from the IR sensor boards are read as, two digital inputs by the micro-controller. Then, the programmed logic makes the Small Robot to make a right or left turn, if digital logic goes LOW (0), else moves forward. To avoid falling on immediate turning, the Small Robot moves little backward, then takes turn accordingly. A button switch, SW1 on control board, is useful to start the Edge Detector, after switching ON the power supply to the Control Board. The complete circuit diagram of Control Board with ATTINY84, is available below. Use jumper wires to connect two OUT pins from Sensor Board to Control board. Enjoy DIY Download ED HEX file Contact for Source Code Download file from above link and remove .TXT extension. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .