A tachometer is a device that is used to measure the speed of rotation of any device. Using the analog voltage reading property of an arduino, this can be easily implemented using the appropriate parts. Tachometers have a variety of applications, including measuring the speed of dc motors in order to ensure they are running according to specifications. In order to make a tachometer, we will have to convert the speed of rotation into a readable form. The only form the arduino can read is in terms of electrical voltage. It is well known that if voltage is given to a motor the motor wheel will turn, the speed of which is determined by the amount of voltage given. However the converse is also true, meaning that if we were to rotate the motor by ourselves, we can obtain a voltage across the two ends of the motor terminals. 

A majority of the wattmeter’s we see today are analog in nature. They consist of numerous moving parts and contain bulky components which not only take up space but also cost a lot of money and are not as accurate as they should be. In this tutorial you will learn how to make a wattmeter which is purely electronic and has no moving parts. The components are also easily available at an affordable price. 

Pulse code modulation is a form of information conversion from discrete to digital. Pulse code modulation is used in almost all modern communication systems and is essential for digital communication. Each sampled value is given in the form of a discrete signal, converted to its binary equivalent, and coded in the form of zeros and ones. There are different types of pulses used for coding ones and zeros. In the following program the user is asked to select the pulse which will then be used to modulate the incoming digital signal. Each discrete signal consists of a set of values. In order to convert this signal into digital form, each discrete value must be represented as its binary equivalent. This binary number can be of any number of bits, where a greater number of bits means better accuracy, but also increased memory and bandwidth usage. 

This tutorial is going to take you through how to make a system which senses which colour is most prominent in the background, using the same principal an LCD screen uses to display colour. It’s is relatively simple to make, while the code is of moderate length. The output is in the form of a hexadecimal value, which is the accepted norm for representing colours, and can be typed in to any picture editing application like paint or Photoshop to give you the resulting colour on your screen. Each pixel on any LCD or LED monitor you own consists of three ‘sub-pixels’ which are nothing but red, green and blue lights. These lights combined make up the 16.9 million colours that are commonly advertised. Each LED is given a voltage value from 0 to 256,to adjust its brightness from completely lit to unlit. This corresponds to an 8-bit hexadecimal number.  

This project is going to guide you through making your very own light level detector, using cheap components and also providing compensation in the form of artificial light whenever the ambient light level in the room is low. Additionally, sensitivity adjustment can also be added for more precise systems.The sensor system can be used for a variety of applications such as an automatic stabilizer for light levels at home or at work, or you can just make one as a fun hobby or for a project.The circuit measures the surrounding light using the photodiodes.Photodiodes are connected in parallel for optimum performance,anode of the diodes is connected to the resistor and also to the analog input pin of the arduino board while the cathode is connected to the power supply.Light received by the diodes is given to the arduino in the form of an analog signal,this signal is processed by the inbuilt ADC of the arduino board. The processed signal is then calibrated to form data which maps to a suitable range. 

A lot of people from engineering and non-engineering departments have trouble with the frequency domain. Many people can show you the frequency domain representation of a time domain signal, but not many can tell you what it means physically or visually. If the best teacher is experience, then no one will have a clue of what lies in the physical representation of the frequency domain. This is mainly because no one thinks in terms of frequency. If a signal is shown to you in the time domain (for example, a rectangular pulse) it is much easier to think of it as just a rectangular signal and not as anything else. This article will show you how to better understand the frequency-domain representation of a signal with as little mathematics as possible, and also show you why it is more convenient in a lot of cases to use the frequency domain for signal analysis. 

Have you ever wondered how thousands of people make phone calls and communicate at the same time, yet there are only 4 wires on each telephone pole, that accommodate all these calls. We all know that the is one wire to our house and one to the house of the person we want to call, but how is it possible that our lines and the lines of every other person living in our neighbourhood, all send information through only one common line, and furthermore, how is everyones information received simultaneously at the other end?The answer lies in a simple concept called time division multiplexing. Although modern telecommunication networks use much faster and more efficient methods, time division multiplexing or TDM for short was an important communication technique in older days, and can still be used effectively for small networks.