tracker cu motor pas_cu_pas pg 2

7/27/2019 Tracker Cu Motor Pas_cu_pas Pg 2

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MICROCONTROLLER- BASED INFRAREDTRACKING ROBOT

Automated system like robots carry out specific tasks. These systems are usuallyemployed in environments where conditions keep changing.

The robot described here senses the 38 kHz infrared radiation and move towardsthat direction.

CIRCIUT DESCRIPTION

Fig. 1 shows the block diagram of the microcontroller-based infrared trackingrobot. It has three sections, namely, sensors , controller and drivers sensingcircuit and microcontroller along with stepper motor circuit are shown in the fig2 and 3 respectively.

MICROCONTROLLER AT89C52 :-

OVERVIEW

A microcontroller (also MCU or C ) is a computer -on-a- chip . It is a type of microprocessor emphasizing self-sufficiency and cost-effectiveness, in contrastto a general-purpose microprocessor (the kind used in a PC). In addition to allarithmetic and logic elements of a general purpose microprocessor, themicrocontroller usually also integrates additional elements such as read-only and

read-write memory, and input/output interfaces.Microcontrollers are frequently used in automatically controlled products anddevices, such as automobile engine control systems, office machines, appliances,

power tools, and toys. By reducing the size, cost, and power consumptioncompared to a design using a separate microprocessor, memory, and input/outputdevices, microcontrollers make it economical to electronically control manymore processes The majority of computer systems in use today are embedded inother machinery, such as telephones, clocks, appliances, and vehicles. Anembedded system may have minimal requirements for memory and programlength. Input and output devices may be discrete switches, relays , or solenoids.An embedded controller may lack any human-readable interface devices at all.For example, embedded systems usually don't have keyboards, screens, disks,

printers, or other recognizable I/O devices of a personal computer Microcontrollers may control electric motors, relays or voltages, and may readswitches, variable resistors or other electronic devices.


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In contrast to general-purpose CPUs, microcontrollers may not implement anexternal address or data bus, because they integrate RAM and non-volatilememory on the same chip as the CPU. Because they need fewer pins, the chipcan be placed in a much smaller, cheaper package. Integrating the memory andother peripherals on a single chip and testing them as a unit increases the cost of that chip, but often results in decreased net cost of the embedded system as awhole.

Originally, microcontrollers were only programmed in assembly language , orlater in C code. Recent microcontrollers integrated with on-chip debug circuitryaccessed by In-circuit emulator via JTAG enables a programmer to debug thesoftware of an embedded system with a debugger .

Some microcontrollers have begun to include a built-in high-level programminglanguage interpreter for greater ease of use. The Intel 8052 and Zilog Z8 wereavailable with BASIC very early on, and BASIC is more recently used in the

popular BASIC Stamp MCUs.

Some microcontrollers such as Analog Device's Blackfin processors can be programmed using LabVIEW , which is a high level programming language.

A microcontroller is a single integrated circuit , commonly with the followingfeatures:

central processing unit - ranging from small and simple 4- bit processorsto complex 32- or 64-bit processors

discrete input and output bits, allowing control or detection of the logicstate of an individual package pin

serial input/output such as serial ports (UARTs ) other serial communications interfaces like IC , Serial Peripheral Interface

and Controller Area Network for system interconnect peripherals such as timers and watchdog volatile memory ( RAM ) for data storage ROM , EPROM , [EEPROM] or Flash memory for program and operating

parameter storage clock generator - often an oscillator for a quartz timing crystal, resonator or

RC circuit many include analog-to-digital converters


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AT89C52 is a low- power , high-performance CMOS 8- bit microcontroller with 8 Kb of downloadable Flash programmable erasable read only memory,2kB of EEPROM ,256 bytes of RAM ,32I/O lines ,programmable watchdogtimers ,two data pointers , three 16-bit timers/ counters , a six-vector two-levelinterrupt architecture , a full duplex serial port , on-chip oscillator and clock circuitry. The device is compatible with the 80C51 instruction set and pin-out.The on-chip downloadable Flash allows the program memory to bereprogrammed interface or by a conventional non-volatile memory programmer.In addition, the AT89C52 is designed with static logic for operation down to zerofrequency and supports two software selectable power-saving modes. The idlemode stops the CPU while allowing the RAM, Timer/ counters, serial port, andinterrupt systems to continue functioning. The power-down mode saves theRAM contents but freezes the oscillators, disabling all other chip functions untilthe next external interrupt or hardware reset is activated. The downloadable

Flash can be changed in steps of a single byte and is accessible through the SPIserial interface. Holding reset a pin high forces the SPI bus into a serial

programming interface and allows the program memory to be written to or readfrom unless lock bits have been activated.

Pin Configurations AT89C52


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Block Diagram of AT89C52


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Serial port and Timer/ counters :

These are important features of AT89C52 that help to simplify the systemdesign required for a number of applications. The serial port is duplex. It has a

buffer that allows next byte to be received before the previous byte has been readfrom the receive register.

TSOP1738:

DescriptionTSOP1738 is a miniaturized receiver for infrared remote control, supporting all

major transmission codes. The PIN diode and preamplifier are assembled on thelead frame. The demodulated output signal can directly be decoded by amicroprocessor.

The TSOP17.. series are miniaturized receivers for infrared remote controlsystems. PIN diode and preamplifier are assembled on lead frame, the epoxy

package is designed as IR filter. The demodulated output signal can directly bedecoded by a microprocessor. TSOP17.. is the standard IR remote controlreceiver series, supporting all major transmission codes.

Features1. Photo detector and preamplifier in one package

2. Internal filter for PCM frequency3. Improved shielding against electrical field disturbance4. TTL and CMOS compatibility5. Output active low6. Low power consumption7. High immunity against ambient light8. Continuous data transmission possible (up to 2400 bps)9. Suitable burst length .10 cycles/burst


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TSOP1738

The circuit of the TSOP17.. is designed in that way that unexpected output pulses due to noise or disturbance signals are avoided. A bandpassfilter, anintegrator stage and an automatic gain control are used to suppress suchdisturbances. The distinguishing mark between data signal and disturbance signalare carrier frequency, burst length and duty cycle.

Block Diagram


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Application Circuit

*) recommended to suppress power supply disturbances

**) The output voltage should not be hold continuously at a voltage below 3.3V by the external circuit.

74121:-

74121 is a monostable multivibrator featuring both positive and negative edgetriggering with complementary outputs. An internal 2-kilo-ohm timing resister is

provided or design convenience minimizing component count and layout programs.

This device can be used with a single external capacitor. Input A is an active-lowtrigger input and input B is an active high transition Schmitt-trigger input thatallows jitter free triggering from inputs with transition rates as low as 1volts/seconds. a high immunity to Vcc noise of typically 1.5V is also provided

by the internal circuitry at the input stage.The basic output pulse width is determined by selection of an internal resistor R INT or an external resistor (R X) and capacitor ( C X). Once triggered, the output

pulse width is independent of further transition of the inputs and is a function of the timing components. Pulse width can vary from a few nanoseconds to 28nanoseconds by choosing appropriate R X and C X combination.Stepper motors: Stepper motor is an electromechanical device or digital motor asit can move in discrete steps and traverse through 360 degrees. Nowadays manycomputer peripherals contain one or more stepper motors.


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ULN2003:

The ULN2003 has high voltage, eight open- collector Darlington pairs withcommon emitters. Each channel is rated at 500mA and can withstand peak currents up to 600mA. Suppression diodes are included for inductive loaddriving and the inputs are pinned opposite the outputs to simplify board layout.

This versatile device is useful for driving a wide range of loads includingsolenoids, relays, DC motors, LED display, filament lamps, thermal print headsand high-power buffers.

SEVEN DARLINGTONS PER PAC. KAGE OUTPUT CURRENT500mA PER DRIVER

.(600mA PEAK) .OUTPUT VOLTAGE 50V INTEGRATEDSUPPRESSION DIODES FOR

.INDUCTIVE LOADS OUTPUTS CAN BE PARALLELED FOR .HIGHER CURRENT .TTL/CMOS/PMOS/DTL COMPATIBLE INPUTS

INPUTS PINNED OPPOSITE OUTPUTS TO SIMPLIFY LAYOUT

These versatile devices are useful for driving a wide range of loads includingsolenoids, relays DC motors, LED displays filament lamps, thermal printheadsand high power buffers.The ULN2001A/2002A/2003A and 2004A are suppliedin 16 pin plastic DIP packages with a copper leadframe to reduce thermalresistance. They are available also in small outline package (SO-16) asULN2001D/2002D/2003D/2004D.

SCHEMATIC DIAGRAM


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PIN CONNECTION( ULN2003 )

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value UnitVo Output Voltage 50 V

Vin - 2004A/D) Input Voltage (for ULN2002A/D -

2003A/D

30 V

Ic ContinuousCollector Current

500 mA

Ib Continuous BaseCurrent

25 mA

Tamb Range OperatingAmbientTemperature

20 to 85 C


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Tstg Range StorageTemperature

55 to 150 C

Tj JunctionTemperature

150 C

Before describing the functioning of the system, here is a brief description of the hardware used in the robot:

PARTS LIST

Semiconductors :

1. IC1-IC3 - 74121 timer 2. IC4-IC6 - TSOP1738 IR receiver module3. IC7 - AT89C52 microcontroller 4. IC8 - ULN2803 darlington array5. IC8 - 7805 5V regulator 6. LED1 - 5mm red LED

Resistors(all -watt, 5% carbon ):

1. R1-R3 - 100 ohm2. R4-R6 - 15 K-ohm3. R7 - 2.2K-ohm4. R8 - 220 ohm5. R9 - 8.2 K-ohm

Capacitors :

1. C1-C3 - 47F, 16V electrolytic2. C4-C6 - 10 F, 16V electrolytic3. C7, C8 - 33 pF ceramic disk 4. C9 - 10 F, 16V electrolytic

Miscellaneous:

1. S1 - ON/OFF switch2. S2 - Push-to-on switch3. X TAL - 12 MHz crystal4. BATTERY - 9V battery


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- stepper motor

WORKING

The TSOP1738 sensor detect IR radiation at a carries frequency of 38kHz.

Three TSOP1738 sensor are used in the circuit for left, centre, and right directionmovements of the object. Depending on the position of the object., one or moresensors are activated .

As the position of the object keeps on changing, there is a continuous change inthe output of the sensors. This data cannot be directly fed as input to themicrocontroller as by the time the microcontroller executes the previous datainstruction, new data input would be lost. Therefore the output of the sensor islatched. This is done through monostable multivibrator IC 74121.The 74121 provides both positive and negative-edge triggering withcomplementary outputs. The on time of the multivibrator is derived from theRC network. Thus T-ON work out 0.69RC, which is 100ms in this case.

At any give instant of time, there can be (2)3 = 8 possible outcomes. Theseoutcomes of the multivibrator are fed to microcontroller AT89C52.AT89C52 has four port. Port P3 is used as an input port and ports P1 and P2 areused as output ports. Bits P3.0, P3.1, and P3.2 are connected to left, mid andright sensors , respectively. In ports P1 and P2, bits P1.0 to P1.3 and bits P2.0 toP2.3 are connected to the left and right motor drivers, respectively. Themicrocontroller processes the input information and outputs at ports P1 and P2.Depending on input combinations to the microcontroller, different actions are

performed by it. These are summarised in the truth table.From the truth table, it is clear that when there is no IR radiation, the input to themicrocontroller is 000. In this situation, the robot rotates in the clockwisedirection, i.e , towards right searching for the IR source present in its vicinity.When the input is 001, i.e the right sensor along gets activated, the robot turnsright. 010 condition is obtained only when centre sensor detects IR radiationsand the robot moves straight. With 100, only the left sensor is activated and the


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robot moves towards left. Similarly, when the input to the microcontroller is110, the robot moves towards left.When all the sensor detect IR radiation, the robot moves straight. The condition101,meansw that the left and right sensor, but not the mid one, detect the IR radiations. This can happen only if there is an obstacle in front of the robot. Sowhen the robot encounters such a combination, it rotates in the anticlockwisedirection, i.e towards left. In other words, if there is any obstacle in its paths, therobot deviates away from it and again starts tracking the object.

However, the output of the ports is not sufficient to drive the stepper motors.Therefore ULN2003, which is a high- voltage and high-current Darlington array,is used in between the microcontroller and the stepper motor to produce enoughcurrent to drive the motors.The stepper motors consisting of four coils, can move both in clockwise and

anticlockwise direction. The direction of the motor depends on the sequence of bits given to them.The sequence of bits that are fed to the stepper motor is as follows:-

For right motor For left motor 0 0 01 0 0 010 0 10 1 0 0 00 1 0 0 0 1 0 0

1 0 0 0 0 0 1 0Thus the subroutine called transfers one or both of the sequences to the stepper motors through the output port. The logic used for controlling the direction of movement of the robot is as follows:If the robot has to move towards right, the left motor should rotate, and vice

versa to movement left. For the forward movement, the right motor should rotatein clockwise direction, whereas the left motor rotates in anti-clockwise direction.

SOFTWARE

The software is assembled using Metalinks ASM51 assembler, which is freelyavailable from the internet and can be downloaded. Source program is workingas per flow chart shown in fig- Subroutine flow charts in straight, left and rightare shown in fig respectively.


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APPLICATION

This robot is designed keeping in mind two applications:-1. Heat-seeking missile2. Fire extinguisher

As a heat- seeking missile :- the heat-seeking missile is a special kind of missile that not only reaches the target emitting heat radiation (aircraft, ship or

boat ) but also tracks it. As the target moves, it follows the target and finallyhits it. The missile is based on the concept of detecting and following the heatradiating source. The robot, designed for 2-dimensional motions, performs thetasks heat-seeking missile as it tracks heat-radiating objects.

As a fire extinguisher:- The robot can be used as a highly sophisticated fireextinguisher, when it detects fire , will move towards fire, deviating away from

any obstatcle, and extinguish the fire.

LIMITATIONSA heat-seeking missile is by itself a complex mechanism of 3-dimensionalmovements in space, which is good for knowledge of thermodynamics and of rocket science. We have simplified it to 2-dimensional movements, which is nota realistic situation.Natural IR radiation have a wide frequency spectrum. However in this project ,

we have brought it down to 38kHz as the sensors used are designed for thiscarrier frequency.

Future enhancements1. the microcontroller can be reprogrammed to increase speed, sensitivity etc.2. for use as a fire extinguisher, a temperature sensor can be added to the robot.

Once the temperature reaches a predetermined value , an interrupt isactivated. This will bring the robot to stop at a safe distance from fire and putout and operate the extinguisher.


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STEPPER MOTER

Stepper motors can be found in almost any piece of electro-mechanicalequipment. From my personal experiences, good sources for stepper motorsinclude

What Is A Step Motor?stepper motor rotates a precise angular distance, one step, for each pulse that isdelivered to its drive circuit. For example, if a particular stepper motor has a stepangle of 7.5 per pulse and the shaft is to be turned through 225 in order to placean object in a certain target position , then it is only necessary to supply 225/7.5=30 pulse to the motor drive circuit .

because the step pulse can be counted digitally and stopped when the desired

number have been deliverd, stepping motor lend themselves to digital control bya programmable controller or micro-computer.

Stepper motors, however, behave differently than standard DC motors. First of all, they cannot run freely by themselves. Stepper motors do as their namesuggests -- they "step" a little bit at a time.Stepper motors also differ from DCmotors in their torque-speed relationship. DC motors generally are not very goodat producing high torque at low speeds, without the aid of a gearing mechanism.Stepper motors, on the other hand, work in the opposite manner. They producethe highest torque at lowspeeds. Stepper motors also have another characteristic,holding torque , which is not present in DC motors. Holding torque allows astepper motor to hold its position firmly when not turning. This can be useful for applications where the motor may be starting and stopping .


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Step motors are electrical motors that are driven by digital pulses rather than acontinuously applied voltage. Inherent in this concept is open-loop control,wherein a train of pulses translates into so many shaft revolutions, with eachrevolution requiring a given number of pulses. Each pulse equals one rotary

increment, or step (hence, step motors), which is only a portion of one completerotation.

HOW STEPPER MOTORS WORK A step motor is an electromagnetic, rotary actuator, that mechanicallyconvertsdigital pulse inputs to incremental shaft rotation. The rotation not only has adirect relation to the number of input pulses, but its speed is related to thefrequency of the pulses .

Between steps, the motor holds its' position (and its' load) without the aid of clutches or brakes. Thus a step motor can be precisely controlled so that it rotatesa certain number of steps, producing mechanical motion through a specificdistance, and then holds its load when it stops. Furthermore, it can repeat theoperation any prescribed number of times. Selecting a step motor and using itadvantageously depends on three criteria: desired mechanical motion, speed, andthe load.


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The motor has six wires, connected to two split windings as is common for unipolar stepper motors. Figure 1 shows the connection diagram for the six leads

Stepper Motor Wiring Diagram. Black and white leads are connected to the common positive supply and forclockwise rotation phases are actuated in the order: A, B, A, B, A, B, A, B,...

In use, the center taps of the windings are typically wired to the positive supply,and the two ends of each winding are alternately grounded through a drive circuitto reverse the direction of the field provided by that winding. The Motor WiringDiagram also illustrates the order of the stator poles in the motor: A, B, A, B.This is the order in which they must be energized to cause the motor to step in aclockwise direction


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MAIN DRIVING CIRCUIT

The advantage of stepper motors are:

1. Directly compatible with digital systems.2. No accumulative positional errors.3. Provide bidirectional rotations with no additional complexities.4. Mechanically simple.5. Reliable and can be repeatedly installed without any damage .


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The two main characteristics of stepper motors are synchronism and constantstep size. These convert digital information and electrical power into positionalinformation and mechanical power

SUBROUTIONE STRAIGHT

DRIVE RIGHT MOTOR IN CW DIRECTIONAND LEFT MOTOR IN ACW DIRECTION

RETURN

Straight subroutine flow chart


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TRUTH TABLE

SUBROUTIONE LEFT

DRIVE RIGHT MOTOR IN CW DIRECTION

RETURN

Left subroutine flow chart

SUBROUTIONE RIGHT

DRIVE LEFT MOTOR IN CW DIRECTION

RETURN

Right subroutine flow chart


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SENSOR OUTPUT

LEFT CENTER RIGHT ACTION

0 0 0 Rotate-CW

0 0 1 Right

0 1 0 Straight0 1 1 Right

1 0 0 Left

1 0 1 Deviate

1 1 0 Left

1 1 1 Straight

Automatic solar tracking system

AUTOMATIC SOLAR TRACKER starts following the SUN right from dawn, throughout the

day, till evening, and starts all over again from dawn next day. On cloudy weathers, it remainsstill and catches the SUN again as it slips out of clouds. It does all this automatically, employscheap and inexpensive components, and is very accurate.Let us see how it does all this.

There are three Electronic Modules to be explained. First one is the HORIZONTAL SENSOR MODULE. It employs the timer 555 in the MONOSTABLE MODE. PIN 2(Trigger Pin of 555)is hooked up with a VOLTAGE DIVIDER NETWORK(PLEASE see FIGURE (2). PIN4(Reset) is hooked up with ANOTHER VOLTAGE DIVIDER NETWORK.


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Fig 1: Block diagram of the tracker following the sun all through


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Fig 2: Horizontal sensor electronic circuit

The LDR(SAY LDR A) which is always illuminated by light through FRESNEL LENSARRAY, has Low Resistance(in presence of light resistance of LDR decreases and vice-versa).We know V(OUT)=V(IN)*[R(bottom)]/[R(bottom)+R(top)], where R stands For Resitance. Soin SUNLIGHT, when LDR As resistance Decreases, VOLTAGE AT PIN 4 Increases. TIMER is no more RESET. PIN 2 is now lower than 1/3 rd Vcc(as the horizontal LDR 1, say LDR Bdoes not initially receive light through its rectangular slit, so its resistance is high(Rtop=8 K ohms), consequently V(OUT) is low). This triggers the timer which gives a pulse to DecadeCounters Clock(14) PIN and triggers it. The Decade Counter CD 4017 gives a NORMALSTEP DRIVE pulse to the Horizontal Unipolar Stepper Motor 1(coupled to the tracker unit) torotate the tracker position so as to receive sunlight(STEP ANGLE of 2 DEGREES). This goeson till the horizontal LDR 1 is fully in SUNLIGHT(resistance low, so PIN 2S VOLTAGEHIGH). Thus the tracker has followed the SUN Horizontally.


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Fig 3: Horizontal Sensor electronic circuit

We will come to the Vertical Sensor Module, but first let us see what the DAWN LDR(SAY

LDR C) does. At night the horizontal Module timer 555 remains Reset(as LDR A is in darknessso its resistance is high, thus pin 4 voltage is low, and the TRACKER points at WEST(whereSUN has set). Next day when SUN rises again in the EAST, the DAWN LDR which is locatedat the back of the TRACKER, points at EAST. So when it receives sunlight its Resistance goeslow, thus Voltage at pin 4 is high and the timer triggers the Decade Counter which in turnswitches the Motor on, thus the TRACKER again moves towards the EAST. Then theTRACKER functions as previously.

Now placed with the Horizontal Sensor LDR 1 is another similar LDR 2 which receives thesunlight as and when does LDR 1. SEE FIGURE 3. So now, as LDR B(THE 1st horizontal one)

receives sunlight, so does Horizontal LDR 2(SEE FIGURE 1, THESE 2 LDRs are placedtogether with same alignment properties and separated by an optically insulated coating(fromeach other).Thus when Motor 1 comes to rest, and as the second horizontal LDR (SAY LDR D),is same way coupled to the second timers(of Vertical Module) Reset pin as was theALWAYS ILLUMINATED LDR A, it brings the second timer out of its Reset mode) by the

previously discussed VOLTAGE RELATIONSHIP). EYE SENSOR LDR(SAY LDR E) of thetracker receives sunlight by an Anti-Reflection Coated, small Rectangular Slit, so reacts onlywhen SUN directly points at it. The second 555s PIN 2 is same way connected to this LDR aswas the first 555s to Horizontal LDR 1. So now that it still not receives sunlight (resistancehigh, so Vout low) and pin 4 is no more Reset, the second CD 4017 MAKES THE SECOND


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STEPPER MOTOR 2 Rotate(Coupled so as to only rotate VERTICAL SENSINGBLOCK/EYE BLOCK ). This movement continues till the SUN directly points at the EYE of our TRACKER. Then the TRACKER STOPS, pointing very accurately at the SUN.FIG 2 andFIG 3 follows.

fig 4: Stepper motor control board

In figure 4 I have only shown the Horizontal Motor Control Circuit. The Vertical One uses asimilar Decade Counter, NPN Transistors, Diodes(to encounter BACK EMF of Power Transistors due to Fast Switching). I chose for a Step Angle of 2 Degrees for the Unipolar Steppers. They are driven in a Normal 4 Step Sequence, first coil A is energised simultaneouslywith coil B ,then coil C with coil D. Thus the Motors rotate by 2 degrees each time. TheCharging Interval(how long pin 3 of 555s remains high) is almost in synchronism with thesteps/second speed of the motors(here 600 steps/sec.), to avoid FALSE TRIGGERING.

NOTE:

1. For 555 in MONOSTABLE MODE, T=1.1*R*C. 2. For the FRESNEL LENS ARRAY , the standard FL 40(Focal Length=0.4 inches) Or FL

65(Focal Length=0.65 inches) FRESNEL LENSES could be used (with the Groovesfacing the LDRs).

3. For the ANTI-REFLECTION COATING, MULTI-LAYER COATING could be used tominimize loss due to REFLECTION. By using alternating layers of a Low-Index materiallike SILICA and a Higher-Index material, it is possible to obtain Reflectivities as low as0.1% at Single Wavelength.

CONCLUSION:We Conclude with the ADVANTAGES of the TRACKER MODULE SYSTEM:

1. Uses SIMPLE, INEXPENSIVE ,EASY TO GET 555 timers and LDRs.


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2. The whole System draws only 25 MicroAmperes of Current when the Motors are notrotating.(555 timers off-state current req. is very less).BATTERY POWER IS SAVED.

3. The TRACKER not only follows SUN from EAST to WEST and back to EAST in acyclic manner(Horizontal Motor Module),but also tracks the Angular Movement of theSUN with respect to its ZENITH ANGLE to the Horizon(Vertical Motor Module andEYE).This is a VERSATILE quality for which the TRACKER could easily be used inconjunction with Solar Panels to derive maximum Solar Energy. Fast Motor

Response(600 steps/sec.),no FALSE TRIGGERING, a Very ACCURATE System, itrequires no Programming Devices(MICROPROCESSORS or MICROCONTROLLERS),so is NOT COMPLICATED.


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6V6 6J5 Class A Vacuum Tube (Valve) Amplifier Circuit

DC Motor Clockwise Anticlockwise Control H-bridge Circuit
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Bi-direction Control Circuit For DC MotorThis circuit can control direction of a DC motor. In many applications we need to operate the motor in bothdirections Clockwise and Anticlockwise (forward and back). One way of achieving this is to connect themotor into a Transistor H-bridge circuit arrangement. H bridge is an electronic circuit that enables a voltage

to be applied across a load in either direction. These circuits are often used in robotics and other applicationsto allow DC motors to run forwards and backwards (Bi-directional).

PARTS LISTR1, R2, R3,R4 220

R5, R6, R7 1KD1, D2, D3,D4 1N4001

D5, D6 LEDQ1, Q2 2SD313


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Q3, Q4 2SB507

PB1, PB2 PUSH BUTTON SWITCH (PUSH TOON)M1 12V DC MOTOR

In this circuit normally PB1 and PB2 are open. So the bases of the transistors are grounded. Hence Q3andQ4 are ON, Q1 and Q2 are OFF. The voltages at both the motor terminals is the same and hence themotor is OFF. Similarly when both PB1 and PB2 are PUSH the motor is OFF.

When PB1 is PUSH, Q1 becomes ON since it is NPN. This type transistor needs high potential at the baseto turn ON. But the Q3 is OFF. Because it is PNP and it needs to low voltage to turn on. PB2 is still OPENso transistor Q2 OFF and Q4 ON because low potential appear at the base of the transistors. So current flowthrough Q1, M1 to Q4. So motor rotates one direction.

When PB2 is ON and PB1 OFF similarly Q2 and Q3 are ON and Q1 and Q4 are OFF. Now current flowsthrough Q3, M1 and Q2. Now motor rotates another direction.

The diodes protect the transistors. They allow back E.M.F. to bypass the transistor.

The LEDs indicate the direction of the motor rotation.

The transistors are EMITTER FOLLOWERS and the voltage on the motor will be less than the voltages of the circuit above because the output voltage will be determined by the slight drop across the 1K+220and the voltage drop across the base-emitter junction of the transistor. The total voltage drop to the motor (due to both sides of the bridge) will be about 2v.

When the both inputs high or low this emitter follower H-bridge circuit has not any current flow. It is the

advantage of this circuit.
http://www.electronicecircuits.com/wp-content/uploads/2012/11/By-Direction-Control-of-DC-Motor-Clockwise-Anticlockwise-Circuit.jpghttp://www.electronicecircuits.com/wp-content/uploads/2012/11/DC-Motor-Direction-control-Clockwise-Anticlockwise-Circuit.jpghttp://www.electronicecircuits.com/wp-content/uploads/2012/11/2SB507-PNP-SILICON-POWER-TRANSISTOR-PINOUT.jpghttp://www.electronicecircuits.com/wp-content/uploads/2012/11/2SD313-NPN-SILICON-POWER-TRANSISTOR-PINOUT.jpg


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Servo motor drive amplifier Digital ICs and opto-isolators provide the drive for this TMOS servo amplifier, resulting in fewer analog circuits and less drift.Fast and consistent turn-on and turn-off characteristics also enable accurate analog output results directly from the digital signalwithout the need for analog feedback. An "H" bridge configuration is employed for the servo amplifier, which obtains

complementary.....
http://www.next.gr/automations/servo-circuits/servo-motor-drive-amplifier-l12184.htmlhttp://www.next.gr/automations/servo-circuits/servo-motor-drive-amplifier-l12184.htmlhttp://www.next.gr/automations/servo-circuits/servo-motor-drive-amplifier-l12184.html

tracker cu motor pas_cu_pas pg 2

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