An Arduino measuring the rotational speed of a basic computer fan. It was one of a number of YouTube videos I did as I was studying for a Masters in Computer Science. This particular module was an embedded systems programming course, with a bit of electronics thrown in. Here`s the video: I was recently asked if the schematics were available for this video. Unfortunately
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I was unable to locate the schematics as shown in the video, however I do have the source code. This is a simple Arduino Sketch that uses an open source Timer` library. You can download the fan-rpm-sketch source code. When reading this source code please keeping in mind that there are three processes going on: b) IR ISR this interrupt routine is configured to be triggered by the falling edge of the IR input i. e. whenever the leading (or falling, I forget which) fan blade edge passes the sensor c) A Timer routine that is attached to a high speed timer and called every second to calculate the RPM value extrapolated from the number of fins seen that second. The difference between the two is the addition of two modules to the layout the thermistor temperature sensor, and the opto-isolated pulse-width-modulated speed controller. On the software side, we now use FreeRTOS on Arduino. The use of an opto-coupler is separates the low voltage Arduino digital IO from the slightly higher voltage used to power the Arduino board and the Fan. Potentially any voltage is supported up to the limits of the CNY 75B part. The IR transistor from radio shack required a large bias resistance to place it in switching` mode rather than amplification mode. A 100K ohm resistor was chosen. An approximate 100 ohm current limiting resistance for the IR LED was provided through two 47ohm resistors in serial. Using the 12V fan in conjunction with...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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