SETH JAI PARKASH MUKAND LAL INSTITUTE OF TECHNOLOGY, RADAUR

To wards partial fulfillment of the requirement of kurukshetra university for bachelor of technology in mechanical engineering

REPORT ONDC POWER SOLENOID ENGINE

PREPARED AND SUBMITTED BY

SANJEEV K.PRABHAKAR ROLL NO.212154

SUNIL KUMAR ROLL NO.212152

RAJESHWAR ROLL NO.212159

SUBMITTED TO :-

MS. MAMTA JAIN MR. V.K. VERMA (PROJECT INCHARGE) H.O.D. (MECH.-ENGG.)

DEPARTMENT OF MECHANICAL ENGINEERINGRADAUR

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Two of the three books mentioned in the lead-up to this page, "Model Making for Young Physicists" by A.D.Bulman and "The Boy Electrician" by Alfred P. Morgan, each presented a model which could be described as a "solenoid engine". The most obvious difference between them is that one of them (Bulman's) had only one solenoid, while Morgan's had two. The most obvious thing that they had in common is that they both relied on moving contacts.

Having built my two-pole electric motor, and thus knowing the hassles moving contacts can cause, I decided in 2010 to build a solenoid engine built on very different principles.

The fact is, my …. and I did build a four-solenoid engine in the late 1990's, based somewhat along the lines of Bulman's model, using an old solenoid my ………… had lying around (goodness only knows where he got it from, or what its original function was!). The model did work, although not very well; eventually it was dismantled, and some of the parts found other uses. As you've probably guessed, the moving contacts were the main cause of its ultimate demise.

Reduced to its bare essentials, a solenoid engine of the moving-contact type can be represented as in the following diagram:

At the right is the solenoid - a coil of wire wound on a tube of suitable non-ferrous material with a movable soft-iron core. This is attached to a crankshaft (at left) which bears a slip-ring and a cam, both made from some suitable metal (eg. brass) and electrically connected together.

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Working Principle of Electromagnetic Piston Engine

The electromagnetic piston engine according to the present invention in one aspect comprises a cylinder and a piston, each made of a magnetic material, a cylinder electromagnet having an inner wall of the cylinder magnetisable to a one magnetic pole, and a piston magnetization unit for magnetizing a portion of the piston engage able with the cylinder to a single magnetic pole in a fixed manner, in which the piston is transferred in a one direction by creating a magnetic attraction force between the cylinder and the piston by exciting the cylinder electromagnet; and the piston is then transferred in the opposite direction by creating a magnetic repellent force there between, followed by repeating this series of the actions of alternately creating the magnetic attraction force and the magnetic repellent force to allow the piston to perform a reciprocal movement.The electromagnetic piston engine according to the present invention in a still further aspect is constructed by arranging a combination of the cylinder with the piston in -the aspects described above as a one assembly, arranging the one assembly in plural numbers and operating the plural assemblies in a parallel way, and converting a reciprocal movement of the piston in each of the plural assemblies into a rotary movement of a single crank shaft by a crank mechanism so that more can be produce for propelling any heavy vehicle.

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Proposed model of Electromagnetic Piston Engine

Single cylinder engine

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Working of engine

FIG. shows an appearance of the cylinder and piston portion of the electromagnetic piston engine. In FIG., reference numeral 1 stands for a piston, reference numeral 2 for a cylinder, reference numeral 3 for an outer cylinder, and reference numerals 4 and 9 each for a connecting portion, each made of a silicon steel plate. The cylinder 2 and the outer cylinder 3 are each of a shape having its top portion closed. An outer wall at the top portion of the cylinder 2 is formed integrally with a connecting portion 4. The cylinder 2 is disposed in the interior of the outer cylinder 3 with the connecting portion 4 arranged so as to come into abutment with an inner wall at the top portion of the outer cylinder 3. The connecting portion 4 is fixed to the top portion of the outer cylinder 3 with a mounting screw 19. An exciting coil 5 is wound about the connecting portion 4. On an outer side of the top portion of the outer cylinder 3 are mounted two electrodes 9 which in turn pass over the entire length to the inner wall side of the outer cylinder 3 and are connected to lead wires at the both ends of the exciting coil 5, respectively, to excite the exciting coil 5 through the electrode .

The piston 1 is of a hollow shape which has an opening on a one side thereof and has a permanent magnet 7 fixed on a base end side thereof so as for the S pole side to be directed to the base end surface of the piston. To the surface of the N pole side of the permanent magnet 7 is fixed a connecting portion 9. An axial hole 9a of the connecting portion 9 is supported axially with a crank shaft of a connecting rod 10 which in turn is axially supported at an axial hole 10a on its other end with a crank mechanism (not shown). The connecting portion 9 is wound with an exciting coil 8 for a booster (herein referred to as "booster coil"). The lead wires on the both sides of the booster coil 8 are connected each to a copper plate electrode 12 embedded extending in the axial direction on the outer wall side surface of the piston.

The piston 1 is supported in the interior of the cylinder 2 with a bearing 15 to enable a smooth reciprocal movement (vertical movement) in the axial direction of the cylinder. The piston 1 is

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arranged to reciprocally move in the distance indicated by "L" in the drawing. The bearing 15 is disposed each in the upper and lower positions along a circumferential direction of the inner wall of the cylinder 2 (i.e. the outer wall of the piston 1) and is made of ceramics so as for the piston 1 to fail to be connected magnetically to the cylinder 2. The bearing 15 may be replaced with as called roller.

The cylinder 2 has a brush electrode 14 (hereinafter referred to simply as "a brush") pass therethrough over its whole length from its outer wall side to its inner wall side and a topside end of the brush 14 is disposed to come slidably into contact with the copper plate electrode 12. The other topside end of the brush 14 is further disposed to pass all the way through the outer cylinder 3 so as to permit a flow of current from the outside. The brush 14 may be made of carbon and the topside end portion of the brush 14 may be formed in the shape of a so-called roller to reduce wear by the sliding movement.

FIG. 3 shows an example of the brush 14 formed at its topside end portion in the shape of such a so-called roller. As shown in the drawing, the brush 14 is mounted at its topside end portion with a cylinder-shaped electrode 14a so as to be rotatable and the cylinder-shaped electrode 14a is disposed to come into contact with the surface of the copper plate electrode 12 while being rotated.

It is to be understood that a contact mechanism for feeding electricity to the booster coil 8 in accordance with the present invention is not restricted to a contact mechanism with the copper plate electrode 12 and the brush 14 and a variety of contact mechanisms may include, for example, such as a slidable contact mechanism in which the connecting rod 10 is made hollow, the lead wire of the booster coil 8 passes through the hollow portion of the connecting rod 10, a ring electrode is mounted on the crank shaft side so as to make a turn in the circumferential direction of a crank shaft, and a brush is disposed to slide together with the ring electrode.

Now, the actions of the electromagnetic piston engine will be described hereinafter.

In operation of the electromagnetic piston engine, a current is fed

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through the booster coil 8 in the direction in which the magnitude of the magnetic pole of the permanent magnet 7 is increased. Although the piston 1 moves reciprocally in the cylinder 2 in a manner as will be described hereinafter, the feeding of electricity to the booster coil 8 can be performed by supplying a current to the copper plate electrode 12 through the sliding copper plate electrode 14. This feeding can excite the whole area of the piston 1 to the S pole by the magnetic forces of the permanent magnet 7 and the booster coil 8.

The excitation of the exciting coil 5 can be performed in a manner as will be described hereinafter. A current is fed in the direction of exciting the cylinder 2 to the S pole and the outer cylinder 3 to the N pole during a period of time during which the piston 1 moves from the top dead center to the bottom dead center (in the direction from bottom to top in the drawing). On the other hand, the current is fed in the direction of magnetizing the cylinder 2 to the N pole and the outer cylinder 3 to the S pole during a period of time during which the piston is being directed to the top dead center from the bottom dead center (from to the top from the bottom in the drawing). The feeding of the exciting current is performed repeatedly in a periodical way.

By exciting the exciting coil 5 in the manner as described hereinabove, the S pole of the piston 1 and the N pole of the cylinder 2 become attracting each other during the time during which the piston 1 moves toward the top dead center from the bottom dead center, thereby raising the piston 1 toward the top dead center by the attracting force. As the piston 1 has reached the top dead center, the exciting current of the exciting coil 5 is inverted. The inversion of the exciting current then excites the cylinder 2 to the S pole to repel the S pole of the piston 1 and the S pole of the cylinder 2 from each other and the repellent force pushes down the piston 1 downwardly toward the bottom dead center. As the piston 1 has reached the bottom dead center, the exciting current of the exciting coil 5 is inverted again. This repetitive actions create a reciprocal movement of the piston 1 in the cylinder 2 and the reciprocal movement is then converted into a rotary movement of a crank shaft 11 through the connecting rod 10.

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Construction

Step-1

We are using ac solenoid coil in our project to give angular motion to our crank shaft.

Coil detail:

Brand: IDEAL -1.0kg/15mm rat,cont, Dc12 v

When we provide current to the coil it core.

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Step-2

We design special crank shaft according to the solenoid coil. We use three iron dicks and pass iron rode from it as shown below diagram.

Use bearing (908) on both side of crank shaft for support it on base and we use chain and sprocket for transmit power to gear box.

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Step-3

We attach solenoid coil with crank shaft as shown below.

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Step-4

We purchased one gear box of 1:4 ratios and fix in between crank shaft and wheel shaft for providing torque to wheel.

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Step-5

We design our project as 4 stork solenoid engine. For distribution different four stork power we using simple electronic technique.the electronic circuit as a timer circuit.

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Component uses

1 9volt battery2 555 timer ic

3 4017 counter ic

4 Vr 100k pot

5 Resistenc

6 Diode

7 Capicitor

8 12 v relay

9 Led

10 12 v battery rechargable

CONPONENT USED

1. 4- Solenoid coil (dc coil)2. Dc Timer circuit3. Power transmitting dick4. Bearing5. Crank shaft (design)6. Washer

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7. Gearbox8. Chain and sprocket9. Wheel10.Wheel shaft11.Wire12.Body frame

Many more as per requirement…….

CONPONENT DETAIL

Used ac solenoid coil

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SolenoidA solenoid is a coil wound into a tightly packed helix. In physics, the term solenoid refers to a long, thin loop of wire, often wrapped around a metallic core, which produces a magnetic field when an electric current is passed through it. Solenoids are important because they can create controlled magnetic fields and can be used as electromagnets. The term solenoid refers specifically to a magnet designed to produce a uniform magnetic field in a volume of space (where some experiment might be carried out).

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Magnetic field of a solenoid

Inside

This is a derivation of the magnetic field around a solenoid that is long enough so that fringe effects can be ignored. In the diagram to the right, we immediately know that the field points in the positive z direction inside the solenoid, and in the negative z direction outside the solenoid.

A solenoid with 3 Ampèrian loops

We see this by applying the right hand grip rule for the field around a wire. If we wrap our right hand around a wire with the thumb pointing in the direction of the current, the curl of the fingers shows how the field behaves. Since we are dealing with a long solenoid, all of the components of the magnetic field not pointing upwards cancel out by symmetry. Outside, a similar cancellation occurs, and the field is only pointing downwards.

Now consider imaginary the loop c that is located inside the solenoid. By Ampère's law, we know that the line integral of B (the magnetic field vector) around this loop is zero, since it encloses no electrical currents (it can be also assumed that the circuital electric field passing through the loop is constant under such conditions: a constant or constantly changing current

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through the solenoid). We have shown above that the field is pointing upwards inside the solenoid, so the horizontal portions of loop c doesn't contribute anything to the integral. Thus the integral of the up side 1 is equal to the integral of the down side 2. Since we can arbitrarily change the dimensions of the loop and get the same result, the only physical explanation is that the integrands are actually equal, that is, the magnetic field inside the solenoid is radially uniform. Note, though, that nothing prohibits it from varying longitudinally which in fact it does.

Applications

Electromechanical solenoids

A 1920 explanation of a commercial solenoid used as an electromechanical actuator

Electromechanical solenoids consist of an electromagnetically inductive coil, wound around a movable steel or iron slug (termed the armature). The coil is shaped such that the armature can be moved in and out of the center, altering the coil's inductance and thereby becoming an electromagnet. The armature is used to provide a mechanical force to some mechanism (such as

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controlling a pneumatic valve). Although typically weak over anything but very short distances, solenoids may be controlled directly by a controller circuit, and thus have very low reaction times.

The force applied to the armature is proportional to the change in inductance of the coil with respect to the change in position of the armature, and the current flowing through the coil (see Faraday's law of induction). The force applied to the armature will always move the armature in a direction that increases the coil's inductance.

Electromechanical solenoids are commonly seen in electronic paintball markers, pinball machines, dot matrix printers and fuel injectors.

Rotary solenoid

The rotary solenoid is an electromechanical device used to rotate a ratcheting mechanism when power is applied. These were used in the 1950s for rotary snap-switch automation in electromechanical controls. Repeated actuation of the rotary solenoid advances the snap-switch forward one position. Two rotary actuators on opposite ends of the rotary snap-switch shaft, can advance or reverse the switch position.

The rotary solenoid has a similar appearance to a linear solenoid, except that the core is mounted in the center of a large flat disk, with two or three inclined grooves cut into the underside of the disk. These grooves align with slots on the solenoid body, with ball bearings in the grooves.

When the solenoid is activated, the core is drawn into the coil, and the disk rotates on the ball bearings in the grooves as it moves towards the coil body. When power is removed, a spring on the disk rotates it back to its starting position, also pulling the core out of the coil.

Rotary voice coil

This is a rotational version of a solenoid. Typically the fixed magnet is on the outside, and the coil part moves in an arc controlled by the current flow through the coils. Rotary voice coils are widely employed in devices such as disk drives.

Pneumatic solenoid valves

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A pneumatic solenoid valve is a switch for routing air to any pneumatic device, usually an actuator, allowing a relatively small signal to control a large device. It is also the interface between electronic controllers and pneumatic systems.

Hydraulic solenoid valves

Hydraulic solenoid valves are in general similar to pneumatic solenoid valves except that they control the flow of hydraulic fluid (oil), often at around 3000 psi (210 bar, 21 MPa, 21 MN/m²). Hydraulic machinery uses solenoids to control the flow of oil to rams or actuators to (for instance) bend sheets of titanium in aerospace manufacturing. Solenoid-controlled valves are often used in irrigation systems, where a relatively weak solenoid opens and closes a small pilot valve, which in turn activates the main valve by applying fluid pressure to a piston or diaphragm that is mechanically coupled to the main valve. Solenoids are also in everyday household items such as washing machines to control the flow and amount of water into the drum.

Transmission solenoids control fluid flow through an automatic transmission and are typically installed in the transmission valve body.

Automobile starter solenoid

In a car or truck, the starter solenoid is part of an automobile starting system. The starter solenoid receives a large electric current from the car battery and a small electric current from the ignition switch. When the ignition switch is turned on (i.e. when the key is turned to start the car), the small electric current forces the starter solenoid to close a pair of heavy contacts, thus relaying the large electric current to the starter motor.

Starter solenoids can also be built into the starter itself, often visible on the outside of the starter. If a starter solenoid receives insufficient power from the battery, it will fail to start the motor, and may produce a rapid 'clicking' or 'clacking' sound. This can be caused by a low or dead battery, by corroded or loose connections in the cable, or by a broken or damaged positive (red) cable from the battery. Any of these will result in some power to the solenoid, but not enough to hold the heavy contacts closed, so the starter motor itself never spins, and the engine does not start.

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Transmission (mechanics)

A Transmission or gearbox provides speed and torque conversions from a rotating power source to another device using gear ratios. In British English the term transmission refers to the whole drive train, including gearbox, clutch, prop shaft (for rear-wheel drive), differential and final drive shafts. The most common use is in motor vehicles, where the transmission adapts the output of the internal combustion engine to the drive wheels. Such engines need to operate at a relatively high rotational speed, which is inappropriate for starting, stopping, and slower travel. The transmission reduces the higher engine speed to the slower wheel speed, increasing torque in the process. Transmissions are also used on pedal bicycles, fixed machines, and anywhere else rotational speed and torque needs to be adapted.

Often, a transmission will have multiple gear ratios (or simply "gears"), with the ability to switch between them as speed varies. This switching may be done manually (by the operator), or automatically. Directional (forward and reverse) control may also be provided. Single-ratio transmissions also exist, which simply change the speed and torque (and sometimes direction) of motor output.

In motor vehicle applications, the transmission will generally be connected to the crankshaft of the engine. The output of the transmission is transmitted via driveshaft to one or more differentials, which in turn drive the wheels. While a differential may also provide gear reduction, its primary purpose is to change the direction of rotation.

Conventional gear/belt transmissions are not the only mechanism for speed/torque adaptation. Alternative mechanisms include torque converters and power transformation.

Uses

Gearboxes have found use in a wide variety of different—often stationary—applications, such as wind turbines.

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Transmissions are also used in agricultural, industrial, construction, mining and automotive equipment. In addition to ordinary transmission equipped with gears, such equipment makes extensive use of the hydrostatic drive and electrical adjustable-speed drives.

BEARINGS Have you ever wondered how things like inline skate wheels and electric motors spin so smoothly and quietly? The answer can be found in a neat little machine called a bearing.

A tapered roller bearing from a manual transmissionThe bearing makes many of the machines we use every day possible. Without bearings, we would be constantly replacing parts that wore out from friction. In this article, we'll learn how bearings work, look at some different kinds of bearings and explain their common uses, and explore some other interesting uses of bearings.

THE BASICSThe concept behind a bearing is very simple: Things roll better than they slide. The wheels on your car are like big bearings. If you had something like skis instead of wheels, your car would be a lot more difficult to push down the road. That is because when things slide, the friction between them causes a force that tends to slow them down. But if the two surfaces can roll over each other, the friction is greatly reduced.

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Bearings reduce friction by providing smooth metal balls or rollers, and a smooth inner and outer metal surface for the balls to roll against. These balls or rollers "bear" the load, allowing the device to spin smoothly.

Bearing LoadsBearings typically have to deal with two kinds of loading, radial and thrust. Depending on where the bearing is being used, it may see all radial loading, all thrust loading or a combination of both.

The bearings that support the shafts of motors and pulleys are subject to a radial load.The bearings in the electric motor and the pulley pictured above face only a radial load. In this case, most of the load comes from the tension in the belt connecting the two pulleys.

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The bearings in this stool are subject to a thrust load.

The bearing above is like the one in a barstool. It is loaded purely in thrust, and the entire load comes from the weight of the person sitting on the stool.

The bearings in a car wheel are subject to both thrust and radial loads.

The bearing above is like the one in the hub of your car wheel. This bearing has to support both a radial load and a thrust load. The radial load comes from the weight of the car, the thrust load comes from the cornering forces when you go around a turn. Types of BearingsThere are many types of bearings, each used for different purposes. These include ball bearings, roller bearings, ball thrust bearings, roller thrust bearings and tapered roller thrust bearings.

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Ball BearingsBall bearings, as shown below, are probably the most common type of bearing. They are found in everything from inline skates to hard drives. These bearings can handle both radial and thrust loads, and is usually found in applications where the load is relatively small.

Cutaway view of a ball bearingIn a ball bearing, the load is transmitted from the outer race to the ball, and from the ball to the inner race. Since the ball is a sphere, it only contacts the inner and outer race at a very small point, which helps it spin very smoothly. But it also means that there is not very much contact area holding that load, so if the bearing is overloaded, the balls can deform or squish, ruining the bearing.

In engineering, the term solenoid may also refer to a variety of transducer devices that convert energy into linear motion. The term is also often used to refer to a solenoid valve, which is an integrated device containing an electromechanical solenoid which actuates either a pneumatic or hydraulic valve, or a solenoid switch, which is a specific type of relay that internally uses an electromechanical solenoid to operate an electrical switch; for example, an automobile starter solenoid, or a linear solenoid, which is an electromechanical solenoid.

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BIKE TIMING CHAIN

DIAMENSION:LENTH: 590MMGROOVE: 84

BIKE TIMING GEAR

DIAMENSION:TEETH: 28LENTH: 90MM

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9 VOLTS MOTOR CYCLE BATTERY

WE HAVE USED A MOTORCYCLE LEAD ACID BATTERY. THIS BATTERY IS OF 9 VOLTS. POWER OF THIS BATTERY IS

USED FOR GLOWING TUBE LIGHT WHEN THE POWER SUPPLY IS OFF. OTHERWISE, THE POWER SUPPLY KEEPS ON

CHARGING THE BATTERY.

DIODE

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If the connections are reversed, a very little current will flow. This is because under this condition, the p-type material will accept the electrons from the negative terminal of the battery and the N-type material will give up its free electrons to the battery, resulting in the state of electrical equilibrium since the N-type material has no more electrons. Thus there will be a small current to flow and the diode is called Reverse biased.

Thus the Diode allows direct current to pass only in one direction while blocking it in the other direction. Power diodes are used in concerting AC into DC. In this, current will flow freely during the first half cycle (forward biased) and practically not at all during the other half cycle (reverse biased). This makes the diode an effective rectifier, which convert ac into pulsating dc. Signal diodes are used in radio circuits for detection. Zener diodes are used in the circuit to control the voltage.

Some common diodes are:-

1. Zener diode.

2. Photo diode.

3. Light Emitting diode.

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1. ZENER DIODE:-

A zener diode is specially designed junction diode, which can operate continuously without being damaged in the region of reverse break down voltage. One of the most important applications of zener diode is the design of constant voltage power supply. The zener diode is joined in reverse bias to d.c. through a resistance R of suitable value.

2. PHOTO DIODE:-

A photo diode is a junction diode made from photo- sensitive semiconductor or material. In such a diode, there is a provision to allow the light of suitable frequency to fall on the p-n junction. It is reverse biased, but the voltage applied is less than the break down voltage. As the intensity of incident light is increased, current goes on increasing till it becomes maximum. The maximum current is called saturation current.

3. LIGHT EMITTING DIODE (LED):-

When a junction diode is forward biased, energy is released at the junction diode is forward biased, energy is released at the junction due to recombination of electrons and holes. In case of silicon and germanium diodes, the energy released is in infrared region. In the junction diode made of gallium arsenate or indium phosphide, the energy is

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released in visible region. Such a junction diode is called a light emitting diode or LED.

555 INTEGRATED CIRCUIT(TIMER OPERATION)

The 555 integrated circuit is an extremely versatile timer that can be used in many different applications. This IC is a monolithic timing circuit that is a highly stable controller capable of producing accurate time delays or oscillations. Additional terminals are producing are provided for triggering or resetting if desires. In the time delay mode of resistance and a capacitor. For a stable operation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200ma or drive TTL Circuits.

This integrated circuit contains nearly 25 transistor, a diode or two, and more than 10 resistors. Obviously, if you built this IC from separate components, it would be many, many times larger than on a monolithic chip.

The 555 timer offers timing from microseconds through hours and operates in both astable and monostable modes. It has an adjustable duty cycle, and the output can drive TTL devices. Its output can operate in normally on and normally off modes and the IC offers a frequency stability of 0.005% per degrees centigrade.

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Applications for the 555 chip include precision timing, pulse generation, pulse width modulation, pulse position modulation, sequential timing, and missing pulse detection.

555-INTEGRATED CIRCUIT

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IC 555-ASTABLE OPERATIONS: -

If the circuit is connected as shown in figure (pins 2 and 6 connected). It will trigger itself and free run as a multivibrator. The external capacitor charges through Ra and Rb and discharges through Rb only. Thus, the duty cycle may be precisely set by the ratio of these two resistors. In this mode of operation the capacitor charges and discharges between 1/3 Vcc and 2/3 Vcc. As in the triggered mode, the charge and discharges times, and therefore, the frequency are independent of the supply voltage. Figure shows the actual waveforms generated in this mode of operation.

The charge time (output high) is given by:t1 = 0.685 (Ra + Rb) C

And the discharge time (output low) by:t2 = 0.685 (Rb) C

Thus, the total period is given by:

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T = t1 + t2 = 0.685 (Ra + 2Rb) C

The frequency of oscillation is then:

f = 1.46 (Ra + 2Rb) C

IC 555-MONOSTABLE OPERATIONS: -

In the monostable mode of operation, the timer

functions as a one shot. Referring to figure the external capacitor is initially held discharged by a transistor inside the timer. Upon applications of a negative trigger pulse to pin 2, the flip-flop is set, which releases the short circuit across the external capacitor and drives the output high. The voltage

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across the capacitor increases exponentially with the time constant.

t = Ra C

When the voltage across the capacitor equals 2/3 Vcc. The comparator resets the flip-flop, which, in turn, discharges the capacitor rapidly and drives the output to its low state. Figure shows the actual waveforms generated in this mode of operation.

The circuit triggers on a negative going input signal when the level reaches 1/3 Vcc. Once triggered, the circuit will remain in this state until the set time is elapsed, even if it is triggered again during this interval. The time that the output is in the high state is given by: t= 1.1 Ra C

Applying a negative pulse to the reset terminal (pin 4) during the timing cycle discharges the external capacitor and causes the cycle to start over again. The timing cycle will now commence on the positive edge of the reset pulse. During the time the reset pulse is applied, the output is driven to its low state.

COUNTERS

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An electronic counter counts the number of pulses entering its ‘clock’ (or ‘trigger’) input. It consists of several flip-flops connected so that they can toggle (p.12). Counting is done in binary code, the ‘high’ and ‘low’ states representing the binary digits (bits) 1 and 0 respectively.

In a ripple or asynchronous counter the output (Q) of one flip-flop feeds the clock input (CK) of the next. This type is satisfactory only for small counts, being slower (because each flip-flop has to wait for a clock pulse from the one before) than the more reliable but more complex synchronous counter in which all flip-flops are clocked simultaneously. The block diagram for an asynchronous counter is shown below using D flip-flops (with D joined to Q bar to give toggling); it can handle four bits, Q4 giving the most significant

4017B DECADE COUNTERThis has ten outputs (Q0 to Q9) and each goes ‘high’ in

turn on the rising edge of successive clock pulses provided that R and CE are both ‘low’.

WHEN R IS TAKEN ‘HIGH’, THE COUNTER RESETS TO ZERO AND IN THIS CONDITION Q10 IS ‘HIGH’ AND ALL OTHER OUTPUTS ARE ‘LOW’. R MUST BE RETURNED TO ‘LOW’ FOR

COUNTING TO START AGAIN. COUNTING STOPS IF CE IS MADE ‘HIGH’ AT ANY TIME.

RIPPLE COUNTER::

A COUNTER IS A REGISTER OF COUNTING THE NUMBER OF CLOCK PULSES THAT HAVE ARRIVED AT ITS CLOCK INPUT.

IN ITS SIMPLEST FORM IT IS THE ELECTRONIC EQUIVALENT OF A BINARY ODOMETER.

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THE CIRCUITFIG. SHOWS A COUNTER BUILT WITH JK FLIP-FLOPS.

SINCE THE J AND K INPUTS ARE RETURNED TO A HIGH VOLTAGE, EACH FLIP-FLOP WILL TOGGLE WHEN ITS CLOCK

INPUT RECEIVES A NEGATIVE EDGE.

HERE'S HOW THE COUNTER WORKS. VISUALIZE THE Q OUTPUTS AS A BINARY WORD: - Q = Q3 Q2 Q1

Q0

Q3 IS THE MOST SIGNIFICANT BIT (MSB), AND Q0 IS THE LEAST SIGNIFICANT BIT (LSB). WHEN CLR GOES LOW; ALL

FLIP-FLOPS RESET. THIS RESULTS IN A DIGITAL WORD OF: -Q = 0000

WHEN CLR RETURNS TO HIGH, THE COUNTER IS READY TO GO. SINCE THE LSB FLIP-FLOP RECEIVES EACH CLOCK

PULSE, Q0 TOGGLES ONCE PER NEGATIVE CLOCK EDGE, AS SHOWN IN THE TIMING DIAGRAM OF FIG. THE REMAINING

FLIP-FLOPS TOGGLE LESS OFTEN BECAUSE THEY RECEIVE THEIR NEGATIVE EDGES FROM THE PRECEDING FLIP-FLOPS.

FOR INSTANCE, WHEN Q0 GOES FROM 1 BACK TO 0, THE Q1 FLIP-FLOP RECEIVES A NEGATIVE EDGE AND TOGGLES. LIKEWISE, WHEN Q1 CHANGES FROM 1 BACK TO 0, THE Q2

FLIP-FLOP GETS A NEGATIVE EDGE AND TOGGLES. AND WHEN Q2 GOES FROM 1 TO 0, THE Q3 FLIP-FLOP TOGGLES. IN OTHER WORDS, WHENEVER A FLIP-FLOP RESETS TO 0, THE

NEXT HIGHER FLIP-FLOP TOGGLES.WHAT DOES THIS REMIND YOU OF? RESET AND CARRY!

EACH FLIP-FLOP ACTS LIKE A WHEEL IN A BINARY ODOMETER; WHENEVER IT RESETS TO 0, IT SENDS A CARRY TO THE NEXT

HIGHER FLIP-FLOP. THEREFORE, THE COUNTER OF FIG. IS THE ELECTRONIC EQUIVALENT OF A BINARY ODOMETER.

COUNTING::

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IF CLR GOES LOW THEN HIGH, THE REGISTER CONTENTS OF FIGURE BECOME

Q = 0000

WHEN THE FIRST CLOCK PULSE HITS THE LSB FLIP-FLOP, Q0 BECOMES A 1. SO THE FIRST OUTPUT WORD IS

Q = 0001

WHEN THE SECOND CLOCK PULSE ARRIVES, Q0 RESETS AND CARRIES; THEREFORE, THE NEXT OUTPUT WORD IS

Q = 0010

THE THIRD CLOCK PULSE ADVANCES Q0 TO 1 THIS GIVES

Q = 0011

THE FOURTH CLOCK PULSE FORCES THE Q0 THE FLIP-FLOP TO RESET AND CARRY. IN TURN, THE Q1 FLIP-FLOP

RESETS AND CARRIES. THE RESULTING OUTPUT WORD IS

Q = 0100

THE FIFTH CLOCK PULSE GIVES

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Q = 0110

AND THE SEVENTH GIVES

Q = 0111

ON THE EIGHTH CLOCK PULSE, Q0 RESETS AND CARRIES, Q1 RESETS AND CARRIES, Q2 RESETS AND

CARRIES, AND Q3 ADVANCES TO 1. SO THE OUTPUT WORD BECOMES

Q = 1000

THE NINTH CLOCK PULSE GIVES

Q = 1001

THE TENTH GIVES

Q = 1010

AND SO ON.

THE LAST WORD IS

Q = 1111CORRESPONDING TO THE FIFTEENTH CLOCK PULSE. THE

NEXT CLOCK PULSE RESETS ALL FLIP-FLOPS. THEREFORE, THE COUNTER RESETS TO

Q = 0000

AND THE CYCLE REPEATS.

TABLE GIVEN SUMMARIZES THE OPERATION OF THE COUNTER. COUNT REPRESENTS THE NUMBER OF CLOCK

PULSES THAT HAVE ARRIVED. AS YOU SEE, THE COUNTER OUTPUT IS THE BINARY EQUIVALENT OF THE DECIMAL

COUNT.

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TABLE: RIPPLE COUNTER

COUNT Q3 Q2 Q1 Q0

0 0 0 0 01 0 0 0

1 2 0 01 0 3 0

0 1 14 0 1 0 05 0 1 0 16 0 1 1 07 0 1 1 18 1 0 0 09 1 0 0 110 1 0 1 011 1 0 1 112 1 1 0 013 1 1 0 114 1 1 1 0

15 1 1 1 1

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RELAY

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Relay is a common, simple application of electromagnetism. It uses an electromagnet made from an iron rod wound with hundreds of fine copper wire. When electricity is applied to the wire, the rod becomes magnetic. A movable contact arm above the rod is then pulled toward the rod until it closes a switch contact. When the electricity is removed, a small spring pulls the contract arm away from the rod until it closes a second switch contact. By means of relay, a current circuit can be broken or closed in one circuit as a result of a current in another circuit.

Relays can have several poles and contacts. The types of contacts could be normally open and normally closed. One closure of the relay can turn on the same normally open contacts; can turn off the other normally closed contacts.

RELAY REQUIRES A CURRENT THROUGH THEIR COILS, FOR WHICH A VOLTAGE IS APPLIED. THIS VOLTAGE FOR A

RELAY CAN BE D.C. LOW VOLTAGES UPTO 24V OR COULD BE 240V A.C.

A relay is an electrical switch that opens and closes under control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts. It was invented by Joseph Henry in 1835. Because a relay is able to control an output circuit of higher power than the input circuit, it can be considered, in a broad sense, to be a form of electrical amplifier.

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These contacts can be either Normally Open (NO), Normally Closed (NC), or change-over contacts.

Normally-open contacts connect the circuit when the relay is activated; the circuit is disconnected when the relay is inactive. It is also called Form A contact or "make" contact. Form A contact is ideal for applications that require to switch a high-current power source from a remote device.

Normally-closed contacts disconnect the circuit when the relay is activated; the circuit is connected when the relay is inactive. It is also called Form B contact or "break" contact. Form B contact is ideal for applications that require the circuit to remain closed until the relay is activated.

Change-over contacts control two circuits: one normally-open contact and one normally-closed contact with a common terminal. It is also called Form C contact.

OPERATIONWhen a current flows through the coil, the resulting magnetic field attracts an armature that is mechanically linked to a moving contact. The movement either makes or breaks a connection with a fixed contact. When the current to the coil is switched off, the armature is returned by a force that is half as strong as the magnetic force to its relaxed position. Usually this is a spring, but gravity is also used commonly in industrial motor starters. Relays are manufactured to operate quickly. In a low voltage application, this is to reduce noise. In a high voltage or high current application, this is to reduce arcing.If the coil is energized with DC, a diode is frequently installed across the coil, to dissipate the energy from the collapsing magnetic field at deactivation, which would otherwise generate a spike of voltage and might cause damage to circuit components. If the coil is designed to be energized with AC, a small copper ring can be crimped to the end of the solenoid. This "shading ring" creates a small out-of-phase current, which increases the minimum pull on the armature during the AC cycle. [1]

By analogy with the functions of the original electromagnetic device, a solid-state relay is made with a thyristor or other solid-state switching device. To achieve electrical isolation, a light-emitting diode (LED) is used with a photo transistor.

Relays are used:

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to control a high-voltage circuit with a low-voltage signal, as in some types of modems,

to control a high-current circuit with a low-current signal, as in the starter solenoid of an automobile,

to detect and isolate faults on transmission and distribution lines by opening and closing circuit breakers (protection relays),

to isolate the controlling circuit from the controlled circuit when the two are at different potentials, for example when controlling a mains-powered device from a low-voltage switch. The latter is often applied to control office lighting as the low voltage wires are easily installed in partitions, which may be often moved as needs change. They may also be controlled by room occupancy detectors in an effort to conserve energy,

to perform logic functions. For example, the boolean AND function is realised by connecting NO relay contacts in series, the OR function by connecting NO contacts in parallel. The change-over or Form C contacts perform the XOR (exclusive or) function. Similar functions for NAND and NOR are accomplished using NC contacts. Due to the failure modes of a relay compared with a semiconductor, they are widely used in safety critical logic, such as the control panels of radioactive waste handling machinery.

to perform time delay functions. Relays can be modified to delay opening or delay closing a set of contacts. A very short (a fraction of a second) delay would use a copper disk between the armature and moving blade assembly. Current flowing in the disk maintains magnetic field for a short time, lengthening release time. For a slightly longer (up to a minute) delay, a dashpot is used. A dashpot is a piston filled with fluid that is allowed to escape slowly. The time period can be varied by increasing or decreasing the flow rate. For longer time periods, a mechanical clockwork timer is installed.

Thanku you

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