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06-01-2011, 04:58 PM

.pdf   DIGITAL SPEEDOMETER.pdf (Size: 1,006.71 KB / Downloads: 1,400)



The aim of our project and implimentation is to develop prototype of a product “Digital Speedometer”. It's used to measure speed up to 999 kmph with a resolution of 1 kmph. It's a hardware project and implimentation done in the field of Digital Electronics and Instrumentation. It can replace ordinary analog speedometer which has low range and resolution. It's rather inexpensive and can be used in almost all vehicles. It can also be used for measuring speed on industrial machinery and modified version of circuitry can be used as an rpm counter.
This Digital Speedometer is provided for use in an automotive vehicle and includes a transducer for connection to a conventional speedometer cable driver. Transducer is equipped with an IR LED and a photo transistor,that produces pulses in response to the rotational motion of the speedometer cable driver. Pulses are transmitted to a counting circuit which is reset by multivibrator circuits. The number of pulses from the transducer is indicative of speed of the vehicle. It is tabulated by the counting circuits during intervals between reset pulses. The number of counts tabulated during each period is passed to a visual display.


The present invention relates to a Digital Speedometer for use with vehicles having internal electrical power supply. In particular, the invention relates to a digital speedometer for automotive vehicles such as auto mobiles, trucks and motor cycles. The Digital Speedometer designed is highly efficient , low cost and can measure speed up to 999 kmph with a resolution of 1kmph.

It‟s dealing with Digital Electronics Circuits and Instrumentation. The main sections of the circuitry are IR section, Comparator, Timer, Counter, Latching section and LED display.

The aim of our experiment is to create an efficient low cost Digital Speedometer. It was inspired by the fact that most of the modern-day vehicles use analog speedometers which have resolution of about 5kmph and the range is also limited.
Historically auto motive vehicles have been provided with mechanical speedometers in which rotation of wheel of the vehicle or of a drive component of the transmission is transmitted as a torsional impulse the torsional force applied to the cable is typically transmitted to needle in the instrument panel which is deflected across a scale to indicate speed at which vehicle is travelling. The Principal dis advantage with such systems has been the requirement for a signal generating system independent of the conventional mechanical speedometer system associated with the auto mobile. It increases the cost of the vehicle.
The Digital Speedometer we have designed can measure up to a speed of 999kmph with a resolution of 1kmph. It‟s rather inexpensive and can be used in almost all vehicles.

Input Section consists of IR LED, photo transistor, a comparator and a mechanical section. An opaque disc is mounted on the spindle attached to the front wheel of the vehicle. This disk has ten equidistant holes on its periphery. On one side of the disc an Infrared LED is fixed and on opposite side of the disc, in line with the IR LED, a phototransistor is mounted. IC LM324 is wired as a comparator.

Timer section consists of astable and monostable multivibrator circuits. So we use IC 556 for this purpose. Astable section is used to trigger the monostable multivibrator. IC 7400(AND gate) is used to set the gating period.

Output section consists of counter and latching sections along with LED display. IC 7490 is used to implement the counter section. The number of pulses counted during the gating period is the speed N in kmph. IC 74175(Quad D flip-flop) is used as the latching circuit. It helps in keeping the LED display constant for a particular period of time so that displayed value could be read. IC 7447 is used as BCD to seven segment decoder. Common anode LEDs are used in the output section to view the speed measured.

An efficient low cost digital speedometer which can measure speed up to 999kmph with a resolution of 1kmph has been designed.
Resolution can be improved by using additional displays.
Circuit can be modified using microcontroller and LCD display

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12-03-2011, 10:06 AM

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.doc   Ashvin Project.doc (Size: 1 MB / Downloads: 314)
The project and implimentation digital speedometer throws light on the concept of measuring speed in automobiles or other related equipment and displaying it suitably. The speed measurement is done with the help of a microcontroller and speed display is done on LCD. The microcontroller used in this project and implimentation PIC 16F73. It is programmed so as to count interrupts. The interrupt is provided using a comparator. The output of comparator is controlled by LDR, which is illuminated by a high intensity LED. This arrangement of LED and LDR is placed on the side of wheel or the rotating part, of which speed is measured. The interrupt generated is counted by the microcontroller and speed is displayed in LCD. This is a simple method of speed measurement.

Encoder is constituted by LED, LDR and comparator. As the disc rotates the illumination level of LED on LDR changes which change the resistance of LDR which in turn varies the voltage in the negative terminal of comparator. The comparator compares the variable voltage in its negative input with constant voltage on its positive terminal. The output of comparator will be low when LDR is not illuminated, i.e., when LED meets the dark portion of disc. The comparator used here is LM358.
LM358 is a low power dual input operational amplifier. It consist of two independent high gain, internally frequency compensated operational amplifiers which were designed specifically to operate from a single power supply over a wide range of voltages. Operation from split power supplies also possible and the low power supply current drain is independent of the magnitude of the power supply voltage. Application areas include transducer amplifiers, DC gain blocks and all the conventional op amp circuits which now can be more easily implemented in single power supply systems.
For example, the LM358 can be directly operated off of the standard +5V power supply voltage which is used in digital systems and will easily provide the required interface electronics without requiring the additional +15V or -15V power supplies.
The microcontroller used here is PIC16F73. The entire function of this speedometer is controlled by this PIC.
• High performance RISC CPU.
• Only 35 single word instruction to learn.
• All single cycle instruction except for program branches which are two cycles.
• Operating speed: DC-20MHz clock input DC-200ns instruction cycle.
• Up to 8K x 14 words of FLASH Program Memory, upon 368 x 8 bytes of Data Memory (RAM).
• Interrupt capability (up to 12 sources).
• Eight level deep hardware stack.
• Direct, Indirect and Relative Addressing modes.
• Processor read access to program memory.
A liquid crystal display (LCD) is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals. It is the final output device that visualizes the calculated speed. LCD used in this project and implimentation has 16 x 2 and it displays 4 bit data.
The whole circuit uses DC supply. A bridge circuit is included in the power supply section to rectify the AC in case 230V mains is used. A power regulator LM7805 is also used to provide a constant DC of +5V.
LM7805 is a switching regulator. Linear Technology manufactures a broad line of high performance switching regulator ICs with both synchronous and non synchronous internal switches. These regulators offer typical input voltage capability from 2.25V up to 60V, switching frequencies up to 4MHz and high efficiency operation up to 96%. Also burst mode operation, quiescent currents in the tens of micro-amps level can be attained. The combination of features allows very small, low profile circuit implementations with minimum external components. Other features include adjustable or synchronizable switching frequency, small in size, and more.
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17-03-2011, 12:17 PM

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.ppt   Digital Speedometer.ppt (Size: 1.18 MB / Downloads: 367)
Digital Speedometer
Analog Gauge
Setbacks of Analog counterpart

Susceptible to external Magnetic Fields which results in a error in the measurement.
Need additional devices to convert the output
Difficult to notice the value in low light conditions.
Aim of the Project
 Detect the speed of rotation digitally.
 Convert the same into speed and display the same in the LCD.
Block Diagram
Components used in the Project

1. AT89S52 Micro Controller
2. IR Module
3. LCD
4. Power Supply
IR Module
 IR represents Infra-Red light which is invincible to Human eye
 Primarily consists Two Components
1. Transmitter [Infra-Red LED]
2. Receiver [Photo Detector]
Photo Detector
Working of the IR Module

For every IR signal given by the LED a positive pulse is generated at the receiving side by the Photo Detector as shown.
Micro Controller
 AT89S52
 Low-Power, High Performance CMOS 8-bit Microcontroller
 Belongs to the Family of 8051
Internal Architecture
Pin Description
Oscillator Connections
Liquid Crystal Display

A general purpose alphanumeric LCD, with two lines of 16 characters
Interfacing LCD to 8051
Regulated Power Supply
 Converts 230V AC supply to 5V DC required for the Microcontroller
Components used for Regulation
1. Step Down Transformer
2. Full Wave Rectifier
3. Voltage Regulator[LM 7805]
 Coding for the Microcontroller is done in ‘Embedded C’
 Dumping of code is done by using the software “Keil µVision”
Speed = Number of pulses
Time x No of holes
 Determining the speed of the vehicles like bikes, car etc by attaching the device to the rotating spindles of wheels.
 Finding the speed of the motors and similar rotating machines in Industries.
 With minor changes can also be used as a counter in the areas like toll booths where number of vehicles passed through it per hour can be calculated.
Future Scope
 By adding a speaker the customer can be warned of high speeding by making different sounds for different speeds.
 By using high capability IR sensors the maximum speed it will handle can also be increased.
 The speed at specific instants can be noted.
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05-04-2011, 12:46 AM

i m doing the same project and implimentation as my mini project and implimentation..
plz can u send mi all the report or information about this project and implimentation..? reply as soon as possible..
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19-12-2011, 02:35 PM

hi i need digital vehicle speedometer with password enabled speed limit setting(using microcontroller) project and implimentation details.
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20-12-2011, 09:51 AM

to get information about the topic"DIGITAL SPEEDOMETER full report" refer the link bellow

rashmi sotwal
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26-02-2012, 11:11 AM

please provide me the full report on digital speedometer
rashmi sotwal
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26-02-2012, 11:22 AM

please provide me with the full report on my major project and implimentation "digital speedometer".
rashmi sotwal
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30-10-2014, 07:50 PM

Thank you for the ppt!!!!
that helped me a lot..and saved much time!!

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