The core of this project (play a sound when a sensor is activated) is applicable to all sorts of areas (Halloween, art installations, scaring your little brother, Burning Man, etc. ), so read this with an eye to applications you`d like to see. My first thought was to hack straight into the elevator`s up and down buttons, but I quickly came to my senses. Building
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managers do NOT want you messing with critical infrastructure (for good reason), and I personally don`t want to get on the bad side of anyone who gets stuck in an elevator because of me. (Around here the winner has been known to choose the loser`s tattoo. ) However, it occurred to me that it might be possible to make a completely self-contained unit, discreetly placed above the elevator`s drop-ceiling, that could detect when the elevator starts moving all by itself. How By using an accelerometer. An accelerometer measures, logically enough, acceleration. This is different from velocity - while a car (or an elevator) is accelerating from stopped to cruising speed, the accelerometer will read > 0. But once the car (or elevator) has reached cruising speed and the velocity is constant, the accelerometer will read 0. When you decelerate, the opposite happens - the accelerometer will read < 0, until the car (or elevator) has stopped, at which point the accelerometer will again read 0. To see what kind of numbers we were dealing with, I hooked up an Arduino, an ADXL345 and an Openlog. (Tip: the Openlog is a great tool for early development work like this - it stores all the data you can generate, making it easy to analyze later and see what you can do with it). I took a quick trip up and down in the elevator, popped out the SD card, loaded the data into a spreadsheet, and made a quick graph: In the above graph, the approximate...
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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