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Friday, November 11, 2016

Review: Embedded Based Contactless Tachometer

The ‘Embedded Based Contactless Tachometer’ as name implies used to measure revolutions per minute of any rotating dc motor.
The Speed of an electric motor is measured as revolutions per second using Tachometer. The Tachometer is available in Analog/Digital, or Contact/Contactless types.
The intended system/project “8051 based Contactless [Digital] Tachometer” is an embedded one. The angular speed of motor is converted into electrical pulses using sensor module. Thus get reading are converted into revolutions per second format and displayed it on user display screen.
This system does not need contact, as in case of mechanical Tachometer. It is also not meant for any mechanical tear-N-wear, or error readings. It is easily portable to any motor or location, as contactless, embedded type, small in size and less power hungry.
The sensor to read revolutions or angular movement of motor is made of LED-LDR combination. The LED or Light Emitting Diode or light source transmits light signal to target white spot, which in turn reflects back to it. This reflected light is read by LDR or light detector and send it to Microcontroller for further processing.
The Microcontroller with the help of memory resident code calculates received signals per minute and displays it on the user screen. In simple term, the Monostable Multi-vibrator with sensor module generates pulses as LDR read white spot on motor shaft [reflected-back LED light], and is fed to Microcontroller chip for further processing.
EmbContactlessTachometer_2016

Objective: Measuring the Revolutions-per-Minute of monitoring motor, and displaying it on LCD screen.
 
Learning curve:
The System is built around AT89c52 Microcontroller. The code does all the calculation/displaying part of the system.
The LED-LDR pair is interfaced with embedded chip to measure rev/min reading, thus learn how to design, calibrate and use any sensor module with controlling chip.
The popular 555 Timer IC is used as Monostable Multivibrator and fed its output pulse to controlling chip for further processing.
 
In reviewed project under/over-speed detection and alarm features are not implemented. User can easily implement both features by referring other similar projects.
Applications:
  • To know RPM of rotating wheels, discs, motor shafts.
  • Where contact is not possible such as in industrial motors, vehicles etc.
 
Title: Microcontroller Based  Contactless Tachometer
External Links: electronicshub.org
 
Keywords: Microcontroller, AT89C52, 555 Timer, LDR, LED, DC Motor

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…till next post, bye-bye & take care.

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