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Advantages of CMOS logic family over TTL

Negligible power dissipation The main advantage of CMOS logic family is their extremely low power consumption. This is because there is no direct conducting path from Vdd to ground in either of input conditions. So there is practically zero power dissipation in STATIC conditioms.There is only dynamic power dissipation, i.e. power is dissipated only during the switching of MOSFETs.   High fan out For TTL logic family the maximum fan out is found to be around 10.Whereas for CMOS logic family fan out rating rating may exceed 50. Hence a larger no of gates can be driven by the output…

A Guide to Understanding Battery Specifications

A battery is a device that converts chemical energy into electrical energy and vice versa. This summary provides an introduction to the terminology used to describe, classify, and compare batteries for hybrid, plug-in hybrid, and electric vehicles. It provides a basic background, defines the variables used to characterize battery operating conditions, and describes the manufacturer specifications used to characterize battery nominal and maximum characteristics.   Battery Basics Cell, modules, and packs– Hybrid and electric vehicles have a high voltage battery pack that consists of individual modules and cells organized in series and parallel. A cell is the smallest, packaged form…

8051 Tutorial 4

The tutorial for the LCD screen will use the basic 1602 type from Hitachi!! This has been cloned to death… Everyone has a copy of this chip set down to mimicking its every function..   I use “Displaytech” and “Fordata” mainly because of the cost… I’m certainly not advertising them.. Use whatever you have… But they have served me well over the past few years…   To use these devices you have to set them up before you can use them…. The chip set can use a variety of sizes, the main ones being 16 character by 2 line, 20…

8051 Tutorial 3

The next tutorial I want to look at a stepping motor… To step a stepper motor we need to sequence the coil windings… The windings are arranged so applying current to the coils in a certain sequence we can turn the motor in small steps.     The sequence shown in the diagram will step the motor in full steps 0AH, 09H, 05H, 06H..The connections are as follows…     To half step the motor then just add a single excitation in between the steps .. As A1 and A2 are on in the first sequence moving to A1 to…

8051 Tutorial 2

Ok… Back on track.   The next tutorial we need to read a 4 x 3 ( 12 key ) keypad…   If we attach a keypad to port 0 and place some resistors as external pull up’s we can read can read the 12 possible on the keypad on only 7 pins… 4 pins as columns and 3 pins as rows.. Here is the connection I used… I have included a 7 segment LED as a simple visual response…     The pinout is shown above… We don’t have enough power to sink the current so I used a…

8051 Tutorial 1

The 8051 micro has been on the scene for a number of years now since the early 80’s.   There are literally hundreds of derivatives.. Ti, Silicon, Atmel, Microchip, Cypress and many many more have come up with several products using this core….. I used Phillips personally. These chips came with a tight boot-loader… With a free program called “Flash Magic” you could simply write a program, compile or assemble to a hex file and flash magic puts it on the device through the serial port.   Boot-loading isn’t a new thing, many devices out today employ a boot-loader… The…

Sensors Demystified

What Is a Sensor? A sensor is a device for detecting and signalling a changing condition. And what is this “changing condition”? Often this is simply the presence or absence of an object or material (discrete sensing). It can also be a measurable quantity like a change in distance, size or color (analog sensing). This information, or the sensor’s output, is the basis for the monitoring and control of a manufacturing process.   Contact vs. Non-Contact Technologies Contact sensors are electromechanical devices that detect change through direct physical contact with the target object. Contact sensors: Typically do not require power…

Who is Lena Soderberg?

Lenna or Lena is the name given to a standard test image widely used in the field of image processing since 1973. It is a picture of Lena Söderberg, shot by photographer Dwight Hooker, cropped from the centerfold of the November 1972 issue of Playboy magazine. Given the nature of the image and its source, several academics have criticized its continued use in scientific publications and higher education as both sexist and unprofessional. Model for Playboy became a superstar within the computer vision community as her picture became one of the most widely used standard test images for compression algorithms….

Why do resistors have color coding when printing the value over the resistor would have been more convenient to the users?

Ever wondered how to see the circuit if you can not *remove* any resistors from their own position from a circuit? Something like this : Question then, how you propose to write the value, where? How can one ensure that the folks who adds those resistors to the circuit, actually takes care of the printed value showing UP so that other people can read the rating? Clearly one can not. There is no way to ensure that. Thus, color coding is mandatory – so that any way, in any configuration one can *read* the values. Why do resistors have color…

Pulse Width Modulation (PWM) – Basics

In layman language, PWM is a technique in which you vary the ratio of HIGH time to LOW time of a pulse. One of the applications is simulation of an analogue signal using digital TTL signals. What if you want to supply 2.5 Volts to a component? You can use a voltage divider circuit using R1=R2 and then supply the output across any one of these resistors to your component of interest. Simple enough? But what you are overlooking is the fact that this circuit is highly inefficient as there is always going to be power dissipation across the resistors….

WHY YOU NEED A CLOCK SOURCE

AN INTRODUCTION TO CHOOSING AND USING CLOCK SOURCES The clock for the AVR is its heartbeat. It basically defines when a processor will do an instruction. Normal instructions for the chip take between one to three clock cycles to complete; a clock cycle is the low-hi-low transition of the clock. So the faster the clock runs, the faster the chip works. This is why a Pentium 1 GHz chip is a LOT faster than a Pentium 100 MHz chip – many more instructions are executed per second. However be careful – the speed of the clock doesn’t actually mean a…

Robotics: Origin and Latest Trends

Out of the shrouds of the myth of imagination, the Science of Robotics took its first faltering steps into the real world half a century back. Its infancy being over, the young discipline is now extending its arms towards diverse goals – to new applications, to new environments, to meet new demands of a new society – Still achieving, still pursuing” in its endless quest for PERFECTION. Robotics is a branch of applied science, the popular conception of which came not from science, but from drama, fiction and cinema. The word “robot” was first used in 1921 by Czech playwright…

Types of robots

There are many ways how you could possibly define different types of robots. As I have seen the possible divisions vary widely. The main reason of these differences is that different tutors often tend to have different views on what should be taught under “robotics”.   For example – some tutors that teach robotics usually focus mainly on industrial robotics, neglecting service robots completely. Therefore when talking about types of robots they usually talk about types of industrial robots. There is a strong reason for this though – the vast majority of robotics engineers will have to deal mostly with…

How to Use Timers in Atmel Microcontrollers

We use timers every day – the simplest one can be found on your wrist. A simple clock will time the seconds, minutes and hours elapsed in a given day – or in the case of a twelve hour clock, since the last half-day. AVR timers do a similar job, measuring a given time interval. An AVR timer in simplest term is a register. Timers generally have a resolution of 8 or 16 bits. So an 8 bit timer is 8 bits wide, and is capable of holding value within 0-255. But this register has a magical property – its…

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