Here we describe a simple process to `put a voice on a sunbeam` and transmit it over a distance. It is a fascinating example of amplitude modulation of light using sound vibrations. We then describe how the modulated light is detected and demodulated in a receiver so that we can hear the sound. A wide range of physics and engineering experience ca
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n be learnt through these exciting `sunbeam` experiments. These activities are inexpensive and can be made in a school laboratory or at home. The interconnected computers forming the Information Super Highway (the Internet) depend on the ability to encode and decode information (e. g. a voice, picture or program) on the communication network. This network might be thousands of miles of wires, fibre optics, under sea cables or use satellites. Although this `information` may appear in an identical from on the distant computer there must be a large amount of encoding / decoding along the way, to make it all happen reliably. The process of encoding information for transmission is called modulation and the subsequent information retrieval is called demodulation. On a computer system a `black box` does this job at either end of the network and is called a Modem (short for Modulator / Demodulator). With other types of information communication, for example in radio broadcasts, the modulation of the programme is done at the transmitter and the demodulation performed within the radio receiver. In the following article however, we look at a more simple system which uses a most basic modulation / demodulation process called amplitude modulation. We will learn about this process in an exciting and entertaining way. Bright sunlight (a sunbeam) will be modulated to carry voice information. Then, after sending it over a distance, we will...
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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