A simple low cost Infrared LED speedometer is described that can be fitted to a skateboard, longboard or even a bicycle to measure speed. Notes on building, setting-up and calibration are given. When used with a low cost data logger continuous measurements of speed can be made while out-and-about. The device forms an interesting science club project and would be
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a great introduction to potential physicists and engineers to scientific instrument design, testing and calibration as well as to generate lots of their own interesting data to analyse. Fig. 1. Longboard skateboard with IR speedometer circuit attached underneath the board. The electronics is housed in the small di-cast box under the board (right). Skateboarding has been around for at least 60 years but in its popular form since the seventies [1]. Recently longboarding has started to become popular with adults as well as with children [1]. The longboard has larger wheels and wider trucks than skateboards making it more stable for adults as well as better equipped for commuting and long trips. YouTube videos show that people are now using longboards on 2000 km treks! [2]. As longboards are generally better made and larger than skateboard they are easier structures on which to develop instrumentation and measurement equipment. It`s great fun to combine science, instrumentation and longboarding. Here we use Infrared (IR) light to monitor the speed of rotation of one of the wheels. Light from an IR LED is directed at one of the wheels. The wheel has a small reflector fixed to it (see below) and when it rotates into position it reflects a signal back to an IR receiver. On reception of the IR beam the receiver o/p pulses low (0V) for a short period. These pulses are too variable to monitor directly but we use them to trigger a...
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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