Summary of Build A Digital Tachometer/RPM Counter using PIC18F452
This tutorial outlines building a low-cost digital tachometer using a PIC18F452 microcontroller to measure computer fan RPMs. The device uses an IR emitter and detector pair; when a fan blade interrupts the signal, the microcontroller counts the changes to calculate rotations per minute. The system is designed for fans operating between 1200 and 3200 RPM, with a total parts cost of approximately $10 if a PIC programmer is already owned.
Parts used in the Digital Tachometer/RPM Counter:
- PIC18F452 microcontroller
- IR emitter diode
- IR detector
- Simple circuitry
- PIC programmer (assumed ownership)
A tachometer is a tool that mechanics or engineers in general use very often. A normal tachometer will be able to tell you how fast something is moving in a complete rotation. A good example is on cars, you will see a tachometer counting the RPMs of your engine.
With the new smaller microcontrollers and some simple circuitry, it’s actually very easy to build your own digital tachometer. This tutorial will make use of an infraded diode and detector to build the digital tachometer/rpm counter. Below are some pictures of the final setup.
Purpose & Overview of this tutorial
This tutorial will build a working digital tachometer that keeps track of the RPMs (rotations per minute) of a computer fan. So it’s really a sophisticated RPM counter module. An IR emitter diode will always be sendind a blanket signal to the IR detector. If a fan blade interrupts the signal the microcontroller will see the change and keep track of each change.
The total cost of parts for this tutorial is around $10 provided you already have a PIC programmer. The RPM counter will be limited to 1200 -> 3200 RPM because this is the computer fan specification for min and max speeds.
For more detail: Build A Digital Tachometer/RPM Counter using PIC18F452
- What is the primary purpose of this tutorial?
To build a working digital tachometer that tracks the RPMs of a computer fan. - How does the microcontroller detect rotation?
An IR emitter sends a signal to an IR detector, and the microcontroller counts each time a fan blade interrupts the signal. - What is the estimated cost of the parts?
The total cost is around $10 provided you already have a PIC programmer. - What are the minimum and maximum speed limits of this project?
The counter is limited to 1200 to 3200 RPM based on the computer fan specifications. - Which microcontroller is used in this build?
The project utilizes a PIC18F452 microcontroller. - Can this device be used for general engine RPMs?
No, this specific tutorial builds a module designed to track the RPMs of a computer fan. - Does the IR emitter send a constant signal?
Yes, the IR emitter diode always sends a blanket signal to the IR detector until interrupted.
