Build your own tachometer with an IR sensor and an Arduino
Build your own tachometer with an IR sensor and an Arduino
Arduino Team — April 25, 2023
A tachometer is a device that displays the speed of a rotating object. The best-known example is the automotive tachometer, which tells the driver the engine speed, particularly useful information when the car is equipped with a manual transmission. But there are many other uses for tachometers and this tutorial by Mirko Pavleski explains how to build a tachometer with an infrared sensor.
To calculate the rotational speed of something like a wheel, you need to monitor at least one point on that wheel and time the interval between passes through a static reference point. A common way to achieve this is to use a Hall effect sensor which detects the magnetic field of a permanent magnet attached to the rim of the wheel. But Hall effect sensors are not suitable for some applications, such as when there are strong magnetic fields nearby. Pavleski's article shows how to use an infrared sensor instead to detect the passage of the spokes of the wheel.
This infrared sensor module works by emitting infrared light from an LED and monitoring the reflection. When one of the spokes of the wheel passes in front of the sensor, the reflection becomes strong and easy to detect. An Arduino Nano board measures the time between these events and multiplies the result by the number of spokes to determine the total time for one full revolution. Divide 60 by this number and you get the RPM. The Arduino continuously calculates this value and displays the number on a small OLED display. Power comes from a 9V battery.
One of the great advantages of this design is that it requires no contact with the object being measured, and because it is portable, one can measure the RPM of anything that spins and has spokes.
Categories: Uncategorized
Arduino Team — April 25, 2023
A tachometer is a device that displays the speed of a rotating object. The best-known example is the automotive tachometer, which tells the driver the engine speed, particularly useful information when the car is equipped with a manual transmission. But there are many other uses for tachometers and this tutorial by Mirko Pavleski explains how to build a tachometer with an infrared sensor.
To calculate the rotational speed of something like a wheel, you need to monitor at least one point on that wheel and time the interval between passes through a static reference point. A common way to achieve this is to use a Hall effect sensor which detects the magnetic field of a permanent magnet attached to the rim of the wheel. But Hall effect sensors are not suitable for some applications, such as when there are strong magnetic fields nearby. Pavleski's article shows how to use an infrared sensor instead to detect the passage of the spokes of the wheel.
This infrared sensor module works by emitting infrared light from an LED and monitoring the reflection. When one of the spokes of the wheel passes in front of the sensor, the reflection becomes strong and easy to detect. An Arduino Nano board measures the time between these events and multiplies the result by the number of spokes to determine the total time for one full revolution. Divide 60 by this number and you get the RPM. The Arduino continuously calculates this value and displays the number on a small OLED display. Power comes from a 9V battery.
One of the great advantages of this design is that it requires no contact with the object being measured, and because it is portable, one can measure the RPM of anything that spins and has spokes.
Categories: Uncategorized
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