The Surfer’s Preserver

The Surfer’s Preserver is a simple device that prevents other phones in the house from disrupting your critical Internet session by disconnecting them from the line while you surf! The circuit is also useful in preventing eavesdropping from other extensions since other phones are "dead" until you hang up.  The circuit wires in series with either of the offending phone’s wires (red or green) and it is small enough to tuck behind the wall cover...

Telephone Ringer

Caution: The circuit generates a high voltage which can shock. The Phone Ringer circuit will work with any ordinary phone including older bell ringer types. The circuit rings the phone in a completely realistic manner until someone answers. When the receiver is lifted the user hears the audio of your choice. It might be another telephone, a tape recording, a favorite talk radio show, a fake busy-signal, a scanner tuned to weather or police, cues...

Telephone In-Use Indicator

When a new computer modem enters the household, the demands on the home phone line skyrockets. The Internet surfer can use phone time on a par with the most talkative teenager. And the computer modem user can be quite sensitive about his privacy: simply lifting another receiver can knock him off-line causing emotional stress. The phone wiring may be modified so that the modem is always in control by connecting the phone line directly to the modem...

Clap-Based Digital Volume Control

This clap-based digital volume control offers four levels of volume control. With each clap, the volume of the audio system increases. After the fourth clap, the level of volume returns to the first or minimum level. The circuit consists of a microphone, a level detector, a 4-stage counter and four analogue switches connected to a resistive ladder network. The four outputs of the CD4040 counter are available at pins 9, 7, 6 and 2. These outputs...

Printing numbers in spiral form using Java

import java.io.*; public class spiral {     public static void main(String args[])throws IOException     {         BufferedReader br=new BufferedReader(new InputStreamReader(System.in));         System.out.print("Enter the value of n:");         int n=Integer.parseInt(br.readLine());         int a[][]=new int[n][n];         int i,j,x=1,p=0,q=n-1;         while(x<=(n*n))         {  ...

Decimal to Roman Conversion using Java

import java.io.*; public class RomanConversion {       // Parallel arrays used in the conversion process.     private static final String[] RCODE = {"M", "CM", "D", "CD", "C", "XC", "L","XL","X","IX", "V","IV","I"};     private static final int[]    BVAL  = {1000, 900, 500, 400,  100,  90,  50, 40,  10,   9,   5,  4,   1};     public static String binaryToRoman(int binary)     {        if (binary <= 0 || binary...

Magic Square using JAVA

import java.io.*; public class MagicSquare {     public static void main(String args[])throws IOException         {             BufferedReader br=new BufferedReader(new InputStreamReader(System.in));             System.out.print("Enter the value of n:");             int n=Integer.parseInt(br.readLine());             if(n%2==0)             {        ...

Linked List Using JAVA

import java.io.*;  class Node{      protected int data;      protected Node link;          public Node(){          link=null;          data=0;         }         public Node (int d,Node n)         {             data=d;             link=n;         }         public void setlink(Node...

Infix To Post Fix using Java

import java.io.*; public class InToPost  {   private Stack theStack;   private String input;   private String output="";   public InToPost(String in)   {     input=in;     int stackSize=input.length();     theStack=new Stack(stackSize);   }   public String doTrans()   {     for (int i=0;i<input.length();i++)     {       char ch=input.charAt(i);       switch(ch)       {       case '+':  ...

Employee Database Using JAVA

import java.io.*; public class employee {     public static void write()throws IOException     {         long empcode;         String empname;         int hrsworked;         double rate;         boolean con=true;         BufferedReader br=new BufferedReader(new InputStreamReader(System.in));         FileOutputStream obj=new FileOutputStream("emp.dat");         DataOutputStream...