12 to 23 Counter

The start and end value of Asynchronous (ripple) counter is controlled by and gate or nand gate. Generally
J K flip flop is have active low preset and clear value so we use Nand gate.
This example give an idea to construct an ripple counter with some start point instead of zero.


Large View

Multiple Door Lock with LCD and Keypad using pic16f877A:

A Brief Description:

This project is written in C language and compile in Mikro C compiler. The basic user lock is of 2 Digits.

The input is taken from a 4x3 Keypad (please see the schematic for more information) and Display the user input on a 2x16 LCD. A pin is assigned as output for activating and deactivating the lock. For demonstration I have connected an LED to that pin.


How combination lock works:

1. Turn switch on (5V DC voltage power supply)
2. A message name “Multiple door Lock” will display on LCD at first row,
3. Second row display “Enter Pass:” it asked you to enter password for open doors.
4. In this lock design it has three doors.  These are the code locks to open doors “door1=55, door2=66, door3=77, door1 & door2 = 33”.

5.      If you entered one of the codes in step 4 then press enter key that door will open.  For example, you enter 05 for door 1 it’s then open and close door 1 after 5 seconds.

6.      If codes you entered are not matched one of the code in step 4 then led door is not turn on.

7. If your first attempt failed the message “invalid code’ display on screen.
8. Then you pressed any key to clear and you can try for second attempt.

After you have reached three attempts but you have not entered correct password.  Next Any Keys press alarm will activate for 5 seconds.

Using the Keypad:
Keypad has 12 keys (4x3) starting from 1,2,3,4,5,6,7,8,9,*,0,# (please see the schematic for layout). Numeric keys are used for entering numbers. '*' is used as the Cancel key and '#' is used as the Enter key.

Source Code Available at ELECTRODATA

BATH ALARM

Here is the block diagram, for a bath alarm which will sound an alarm before the water in the bath overflows:

The float sensor consists of a voltage divider with a float switch at the top and a 100 k pull down resistor at the bottom. If the water level rises above a critical level, the float switch closes and the output of this subsystem becomes HIGH, logic 1.                                                                          
The astable, or pulse generator, produces pulses. Its output alternates repeatedly from HIGH to LOW. The float sensor provides a control input to the AND gate. If the control input is LOW, the output of the AND gate remains LOW. However, if the control input goes HIGH, the output of the AND gate starts to produce pulses, alternately HIGH and LOW, following the astable.
The transducer driver is needed to provide enough current to drive the buzzer. When the bath is full, the buzzer pulses ON and OFF.
It is easy to model this system using the system blocks provided by Crocodile Technology ©:

Open in Large

Holographic Memory

Holographic data storage is a potential technology in the area of high-capacity data storage currently dominated by magnetic and conventional optical data storage. Magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium. Holographic data storage records information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles.
Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by traditional optical storage.

Holographic data storage contains information using an optical interference pattern within a thick, photosensitive optical material. Light from a single laser beam is divided into two separate optical patterns of dark and light pixels. By adjusting the reference beam angle, wavelength, or media position, a multitude of holograms (theoretically, several thousand) can be stored on a single volume.

The stored data is read through the reproduction of the same reference beam used to create the hologram. The reference beam’s light is focused on the photosensitive material, illuminating the appropriate interference pattern, the light diffracts on the interference pattern, and projects the pattern onto a detector. The detector is capable of reading the data in parallel, over one million bits at once, resulting in the fast data transfer rate. Files on the holographic drive can be accessed in less than 200 milliseconds.

Holographic Memory





Download in on ELECTRODATA

Matlab for beginners continue...

Here are some example to understand the discrete function in signal system engineering.....

% Plot unit step sequence , sinusoidal sequence exponential sequence
% to generate a unit step sequence
N= 31;
x1 =  ones(1,N);   % the one give 1 by N matrix of ones
n = 0:1:N-1;
subplot(2,2,1),stem(n,x1);  % stem is use to plot descret point
xlabel('n'),ylabel('x_1(n)');
title('Unit Step Sequence');   % title command give the title of graph
axis([0 30 0 2]);

%sinusoidal sequence
x2= 2*cos(.1*pi*n);
subplot(2,2,2),stem(n,x2);
xlabel('n'),ylabel('x_2(n)');
title('Sinusoidal Sequence');

%Exponetial Sequence
x3= 0.6.^(n);
subplot(2,2,3),stem(n,x3);
xlabel('n'),ylabel('x_3(n)');
title('Exponential Sequence');

% Addition of two sinusoidal sequence
x4 = sin(.5*pi*n)+ sin(.25*pi*n)
subplot(2,2,4),stem(n,x4);
xlabel('n'),ylabel('x_4(n)');
title('Addition of two Sequence');

% plot a typical exponental sequence a^n when 1. 0<a<1 ,2. -1<a<0...
...3. a>1, 4. a<-1
 
clear all;
a= .8
n= -10:1:10;
x1 = a.^n;
subplot(2,2,1),stem(n,x1);
xlabel('n'),ylabel('x_1(n)');

a=-0.8;
x2 = a.^n;
subplot(2,2,2),stem(n,x2);
xlabel('n'),ylabel('x_2(n)');

a=1.15;
x3 = a.^n;
subplot(2,2,3),stem(n,x3);
xlabel('n'),ylabel('x_3(n)');

a= -1.15;
x4 = a.^n;
subplot(2,2,4),stem(n,x4);
xlabel('n'),ylabel('x_4(n)');

THYRISTOR

The thyristor is a four-layer, three terminal semiconducting device, with each layer consisting of alternately N-type  or P-type material, for example P-N-P-N. Four-layer devices act as either open or closed switches; for this reason, they are most frequently used in control applications. They stay on once they are triggered, and will go off only if current is too low or when triggered off. The SCR is the most widely used and important member of the thyristor family. The SCR is almost universally referred to as thyristor. Common areas of application for SCRs are  Time-delay circuits, regulated power suppliers, static switches, motor controls choppers, battery charger and heater controls. Etch..

Thyristors can take many forms, but they have certain things in common. All of them are solid state switches which

act as open circuits capable of withstanding the rated voltage until triggered. When they are triggered, thyristors

 become low−impedance current paths and remain in that condition until the current either stops or drops below a minimum value called the holding level. Once a thyristor has been triggered, the trigger current can be removed without turning off the device. Silicon controlled rectifiers (SCRs) and triacs are both members of the thyristor family. SCRs are unidirectional devices where triacs are bidirectional. An SCR is designed to switch load current in one direction, while a triac is designed to conduct load current in either direction. Structurally, all thyristors consist of several alternating layers of opposite P and N silicon, with the exact structure varying with the particular kind of device. The load is applied across the multiple junctions and the trigger current is injected at one of them. The trigger current allows the load current to flow through the device, setting up a regenerative action which keeps the current flowing even after the trigger is removed. These characteristics make thyristors extremely useful in control applications. Compared to a mechanical switch, a thyristor has a very long service life and very fast turn on and turn off times. Because of their fast reaction times, regenerative action and low resistance once triggered, thyristors are useful as power controllers and transient overvoltage protectors, as well as simply turning devices on and off. Thyristors are used in motor controls, incandescent lights, home appliances, cameras, office equipment, programmable logic controls, ground fault interrupters, dimmer switches, power tools, telecommunication equipment, power supplies, timers, capacitor discharge ignitors, engine ignition systems, and many other kinds of equipment.

THYRISTOR


Here i give a proper format of seminar on topic Thyristor. The report file of this ppt also enclosure with the ppt at ELECTRODATA

Download PPt and report

Click Here!

MATLAB for beginners

MATLAB ( MATrix LABoraory ) is a high - performance language for high efficiency  Engineering and scientific numerical calculations. It was original developed to provide easy acces to matrix software developed by the LINPACK and ESIPACK matrix computation software . The MATLAB environment allows us to integrate user freindly tools with superior computational  capabilities . As a result , MATLAB is one of the most useful tools for Scientific and Engineering calculation and Computing.

You can use MATLAB in a wide range of applications, including signal and image processing, communications, control design, test and measurement, financial modeling and analysis, and computational biology.

To the beginner it's my suggestion that the download  the Matlab and keep practice with the problem . The Matlab Help is fully compatible to the new user and  it explains every funtion with example. Here i give some Practice to generate a continuous signal . To understand the MATLAB window see the Getting Start MATLAB tutorial in HELP. I have also linked the Introduction to Matlab ppt on my post .

% To plot a continoius time signal                          /% is use before comment

%1 sinusoidal signal
clear all;                   % it removes all variables from the workspace, releasing them from system memory.
T = 0.2;        % time period in sec
t= -1:0.01:1;    % generate a time index with interval of 0.01
x1 =  sin(2*pi*t/T);        % sine function
subplot(2,2,1),plot(t,x1);      % it create a matrix form of the plot (row column position )     
xlabel('\itt'),ylabel('x_1(\itt)');    % xlabel and ylable is use for label the axis

%2 exp signal
x2 = exp(-2*t);
subplot(2,2,2),plot(t,x2);
xlabel('\itt'),ylabel('x_2(\itt)');

% 3 sawtooth signal
t1 = -20:0.01:20;
x3 =  sawtooth(t1);
subplot(2,2,3), plot(t1,x3)
xlabel('\itt'),ylabel('x_3(\itt)');

% 4 suare signal
x4 = square (t1);
subplot(2,2,4),plot(t1,x4);
xlabel('\itt'),ylabel('x_4(\itt)');
axis([-20 20 -1.5 1.5]);     % this command provide range of axis [xmin xmax ymin ymax] in matrix form


% plot countinious signals
% 1 sinc function
clear all;
t = -20:0.01:20;
x1 =  sinc(t/2);
subplot(2,2,1),plot(t,x1);
xlabel('\itt'),ylabel('x_1(\itt)');
axis([-20 20 -1.5 1.5]);

%2 rectanfular signal
x2 = rectpuls(t/10);
subplot(2,2,2),plot(t,x2);
xlabel('\itt'),ylabel('x_2(\itt)');
axis([-20 20 -1.5 1.5]);

% 3 triangular signal
x3 =  tripuls(t/10);
subplot(2,2,3), plot(t,x3)
xlabel('\itt'),ylabel('x_3(\itt)');
axis([-20 20 -1.5 1.5]);

% 4 signum signal
x4 = sign(t/3)
subplot(2,2,4),plot(t,x4);
xlabel('\itt'),ylabel('x_4(\itt)');
axis([-20 20 -1.5 1.5]);


% plot prdouct of two function
% 1
clear all;
t = -2:0.01:2; T = .2; T1=4;
x1 = sin(2*pi*t/T).*exp(-2*t);                           % for the product of two function we use
                                                                              Multiplication: Element-wise(.*) operator
subplot(2,2,1),plot(t,x1);
xlabel('\itt'),ylabel('x_1(\itt)');

%2 rectanfular signal
T2= .3; T3=2;
x2 = 2*cos(2*pi*t/T2).*sin(2*pi*t/T3);
subplot(2,2,2),plot(t,x2);
xlabel('\itt'),ylabel('x_2(\itt)');

% 3 triangular signal
x3 =  sin(2*pi*t/T).*exp(-2*t) + sin(2*pi*t/T1).*exp(-4*t);
subplot(2,2,3), plot(t,x3)
xlabel('\itt'),ylabel('x_3(\itt)');

% 4 signum signal
x4 = sinc(t).*sin(2*pi*t/T);
subplot(2,2,4),plot(t,x4);
xlabel('\itt'),ylabel('x_4(\itt)');

to create a function x= y(t) such that 

y(t) = t+5 when -5<t<=-2

      = 11 +4t when -2 <t<= 1

     =  24-9t  when 1<t<=3

     =  t-6  when 3<t<=6

Program

function x =y(t)

x1 = t+5; x2 = 11 + 4*t; x3 = 24 - 9*t; x4= t-6;

x = x1.*(-5<t&t<=-2) + x2.*(-2<t& t<=1) + x3.*(1<t&t<=3) + x4.*(3<t&t<=6);

%this  file is save with .m extension which is a function file now the y(t) work as function you can use it in  your own program.  To use it first it must be included in your working directory 

How to use this created function is explain by the following program

clear all;

tmin= -15 ; tmax= 20;

t= tmin:0.1:tmax;

y0 = y(t);

y1 = y(t+4);

y2 = 2*y(t-3);

y3 = y(2*t);

y4 = y(2*t-3);

y5 = y(t/2);

ymax = max([max(y0),max(y1),max(y2),max(y3),max(y4),max(y5)]);

ymin = min([min(y0),min(y1),min(y2),min(y3),min(y4),min(y5)]);

subplot(3,2,1), plot(t,y0);

xlabel('\itt'),ylabel('y_0(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,2), plot(t,y1);

xlabel('\itt'),ylabel('y_1(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,3), plot(t,y2);

xlabel('\itt'),ylabel('y_2(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,4), plot(t,y3);

xlabel('\itt'),ylabel('y_3(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,5), plot(t,y4);

xlabel('\itt'),ylabel('y_4(\itt))');

axis([tmin tmax ymin ymax]);

subplot(3,2,6), plot(t,y5);

xlabel('\itt'),ylabel('y_5(\itt))');

axis([tmin tmax ymin ymax]);