04-09-2014, 04:20 PM
Tachometer USING 8051 MICROCONTROLLER
[attachment=67644]
What is Tachometer
A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine.The device usually displays the revolutions per minute (RPM) on a calibrated analogue dial, but digital displays are increasingly common
INTRODUCTION
AT89S51 belonging to the 8051 family is the microcontroller used here.
It can simply divided into 2 sections:-
1)Sensor Section
3)Display Section(LED display)
FEATURES
AT89C51 is a 40 pin IC
AT89C51 is a low power, high performance CMOS 8-bit microcontroller
4K Bytes of In-System Reprogrammable Flash Memory
Fully static operation:0Hz-24MHz
32 programmable i/o lines
128 bytes internal RAM
Working
A three digit contact less digital tachometer using 8051 microcontroller which can be used for measuring the revolutions/second of a rotating wheel, disc, shaft or anything like that is introduced in this project. The tachometer can measure up to a maximum of 255 rev/sec at an accuracy of 1 rev/sec. What you just need to do is to align the sensor close to the reflective strip (aluminium foil, white paper or some thing like that) glued on the rotating surface and the meter shows the rev/sec on the display.
Working of circuitry
The first section of the circuit is the optical pickup based on photo transistor Q4 and red LED D4. Every time the reflective stripe on the rotating object passes in front of the sensor assembly, the reflected light falls on the photo transistor which makes it conduct more and as a result its collector voltage drops towards zero. When viewed through an oscilloscope the collector waveform of the photo transistor Q4 (2N5777) would look like this
Next part is the signal conditioning unit based on the opamp LM324 (IC1). Only one opamp inside the quad LM324 is used here and it is wired as a comparator with reference voltage set at 3.5V (using resistors R16 and R17). The job of this comparator unit is to convert the spiky collector wave form into a neat square pulse train so that it can be applied to the microcontroller. Every time the collector voltage of the photo transistor goes below 3.5V, the output of the comparator goes to negative saturation and every time the collector voltage of the photo transistor goes above 3.5V, the comparator output goes to positive saturation resulting in a waveform like this:
Applicatioin
Measurement of speed for automobiles.
RPM measurement of shafts in industries
[attachment=67644]
What is Tachometer
A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine.The device usually displays the revolutions per minute (RPM) on a calibrated analogue dial, but digital displays are increasingly common
INTRODUCTION
AT89S51 belonging to the 8051 family is the microcontroller used here.
It can simply divided into 2 sections:-
1)Sensor Section
3)Display Section(LED display)
FEATURES
AT89C51 is a 40 pin IC
AT89C51 is a low power, high performance CMOS 8-bit microcontroller
4K Bytes of In-System Reprogrammable Flash Memory
Fully static operation:0Hz-24MHz
32 programmable i/o lines
128 bytes internal RAM
Working
A three digit contact less digital tachometer using 8051 microcontroller which can be used for measuring the revolutions/second of a rotating wheel, disc, shaft or anything like that is introduced in this project. The tachometer can measure up to a maximum of 255 rev/sec at an accuracy of 1 rev/sec. What you just need to do is to align the sensor close to the reflective strip (aluminium foil, white paper or some thing like that) glued on the rotating surface and the meter shows the rev/sec on the display.
Working of circuitry
The first section of the circuit is the optical pickup based on photo transistor Q4 and red LED D4. Every time the reflective stripe on the rotating object passes in front of the sensor assembly, the reflected light falls on the photo transistor which makes it conduct more and as a result its collector voltage drops towards zero. When viewed through an oscilloscope the collector waveform of the photo transistor Q4 (2N5777) would look like this
Next part is the signal conditioning unit based on the opamp LM324 (IC1). Only one opamp inside the quad LM324 is used here and it is wired as a comparator with reference voltage set at 3.5V (using resistors R16 and R17). The job of this comparator unit is to convert the spiky collector wave form into a neat square pulse train so that it can be applied to the microcontroller. Every time the collector voltage of the photo transistor goes below 3.5V, the output of the comparator goes to negative saturation and every time the collector voltage of the photo transistor goes above 3.5V, the comparator output goes to positive saturation resulting in a waveform like this:
Applicatioin
Measurement of speed for automobiles.
RPM measurement of shafts in industries