Electro18 posted a tutorial on how to make a portable digital optical tachometer using an Arduino Uno, an instructable here:
A tachometer is a device used to measure the RPM or Revolutions Per Minute of any rotating body. Tachometers can be contact based or non-contact ones. The non-contact or contact-less optical tachometers usually use laser or Infrared beam to monitor the rotation of any body. This is done by calculating time taken for one rotation.
It can measure RPM over 20k
Sensor range extends upto 7~8 cm
Displays Maximum RPM
Measure RPM – DIY portable digital tachometer - [Link]
praveen @ circuitstoday.com writes:
Tachometer is a device used for measuring the number of revolutions of an object in a given interval of time. Usually it is expressed in revolutions per minute or RPM. Earlier tachometers purely mechanical where the revolution is transferred to the tachometer through mechanical coupling (cable or shaft) , the rpm is determined using a gear mechanism and it is displayed on a dial. With the advent of modern electronics, the tachometers have changed a lot. This article is about a contactless digital tachometer using arduino. The speed of the motor can be also controlled using the same circuit. The RPM and all the other informations are displayed on a 16×2 LCD screen. The circuit diagram of the digital tachometer using arduino is shown below.
Tachometer using arduino - [Link]
Chris @ PyroElectro.com writes:
A tachometer is a useful tool for counting the RPM (rotations per minute) of a wheel or basically anything that spins. The easiest way to build a tachometer is using a transmitter and receiver. When the link between them is broken, you know that something is spinning and can execute some code that calculates the current RPM of whatever is spinning to break the transmitter/receiver link.
In this article we will explore how to use an IR transmitter and receiver break-beam pair similar to the PIC Tachometer project I built a few months ago, but because of popular demand, the Arduino system will be used for all the processing and break-beam interruption counting. The end result will be a 16×2 LCD displaying the RPM of some computer fans.
Arduino Tachometer - [Link]
I’m really very happy to present this circuit! This is a very special page, and what’s special about it is that this circuit is designed NOT by me, but from a PCB Heaven reader, which happens to be also one of my students in my PIC classes. As a matter of fact, he is my first student… Well, ok, he is my only student :). So, this is the very first circuit page that i host in my site which is designed by a PCB Heaven reader. Special thanks to Panagioti Kalogeri, which you will find him trolling around my site with the id _Pike…
This circuit is the result of an exercise that i asked him to make, in order to practice with the Timer modules of the PIC. The PIC will read the tacho output of a PC fan. The rpm is then translated into a number of LEDs turned-on on the bar-graph. The minimum rpm during which only one LED is turned on is 600 rpm, and the maximum is 1200 – which is also the max speed of the fan. Panagiotis was asked to implement the rpm measurement with the Reverse Frequency Measuring as described here.
PC Fan RPM Bargraph Meter with PIC - [Link]
quipped with sophisticated Enhanced Capture/Compare/PWM (ECCP) peripheral the Microchip PIC18F14K50 microcontroller could produce up to four PWM channels output. The enhanced PWM (Pulse Width Modulation) mode in ECCP peripheral is capable to drive the full bridge DC Motor circuit directly both in forward or reverse direction. It also could generate single PWM output on the selectable PIC18F14K50 pins when it configured in pulse steering mode. In this tutorial we will take advantage of PIC18F14K50 pulse steering mode to drive the DC Motor and at the same time we will build the RPM (Rotation per Minute) counter to observe the PWM effect on the DC Motor speed and display it on the 2×16 LCD.
PIC18 Pulse Width Modulation (PWM) DC Motor Speed Controller with the RPM Counter Project - [Link]
This is a very basic lesson on how to make a contact-less digital tachometer using infrared light reflection technique. It can measure RPM up to 99960 and the resolution is 60 RPM.
How to make a contact-less digital tachometer using IR-light reflection technique – [Link]
This is a small, off-the-shelf, DIY digital tachometer that uses a photo-interruptor (IR emitter/detector) to keep track of the RPM of anything. It’s a simple yet very effective design that I thought you might like. The RPMs of a desktop computer fan are tracked as an example with this system.
Build A Digital Tachometer / RPM Counter – [Link]
This article shows how to convert a servo into and geared motor.
But, you still want the RPMs of a servo without the hassle of the pulsing control. So, you hack the servo and make it a geared motor. Easy! Here’s how…
Turn a Servo Into an Inexpensive Geared Motor – [Link]
The OBDuino is an in-car real-time display of various information, like speed, RPM, instant fuel consumption or average trip fuel consumption as well as others PIDs supported by the car. It reads the data from the car’s OBD-II connector, interfacing it via a MC33290 chip to the Arduino which processes the CAN data and outputs to a 2×16 LCD. [via]
OBDuino: car diagnostics with Arduino - [Link]
Tachometer is used to measure the rotational speed of any shaft or disc. The unit of the measurement is rotation per minute or just RPM. This project describes a contact-less tachometer based on PIC16F628A microcontroller. The rotation of a disc is measured through a set of IR module that converts one complete rotation into a pulse. The result is displayed in a multiplexed seven segment display.
Contact-less Tachometer using PIC16F628A Microcontroller – [Link]