|           Here is a PC based 
      Game show/ quiz buzzer, which makes a quiz 'priority less'. Instead of allowing only 
      the first person who presses the buzzer first to answer, this buzzer 
      introduces a new idea called 'Priority passing'. Uses PC parallel port to 
      input response from the buzzer.    Introduction:          The attraction of any game show depends on the 
      visual effects. The way in which they present different rounds makes the 
      game shows effective. The good Quiz show always contains one or more 
      buzzer rounds. The buzzer makes a round of a Quiz show 'fastest finger first '. The 
      active buzzer makes the team to first respond to the question. A common 
      question will be asked for all the teams in these rounds. The team which 
      presses the buzzer first gets first chance to answer. To avoid confusion 
      of the teams to be answered when one or more team presses the buzzer 
      almost simultaneously, buzzer circuits are used.
 
          Instead of just showing who pressed the buzzer using 
      some LED or electric 
      bulb, if has some visual effects, audio effects and different options that 
      makes the show entice. So our approach is to make this possible which 
      includes all the features. This project makes the show attractive and easy 
      to operate. This Quiz buzzer is built with the view of making the game 
      show 
      priority less.          
      This project uses PC parallel port to input user's response from the 
      switches placed in the participant's table. Response of the teams can be 
      projected on to a screen. Number of all the teams will be displayed in the 
      screen in order of the response.          
      This project uses Turbo C version 3.0 for programming. If you don't know 
      the parallel port interfacing, read
      
      http://electrosofts.com/parallel :
      Parallel port interfacing 
      tutorial. If you are using windows xp and other compilers, you may need to 
      read Parallel 
      port interfacing: windows. You can use this idea and convert the 
      project for windows, try it... Circuit This project uses parallel port in 
      normal( unidirectional ) mode. So, we have only 5 input pins available. 
      Here, we assumed there are 6 teams. So we need extra input pins. This can 
      be done by multiplexing the signals.  Circuit of the quiz buzzer consists of 
      the following components: 
        
        Multiplexer IC 74157
        10kΩ resistors (6)
        5volt dc power supply
        D-25 type connectors
        Push switches (6) 
               The circuit diagram is as shown 
      above.  the pins 10,11,12,14 of the D-25 connector are connected to the IC 
      as in the diagram. The pins from 18 to 25 are grounded. Another end of the 
      cable is connected to the LPT1 port of the PC.    Logic diagram of IC 74157
  Next part contains the C code of the project and 
      description of the working. Continue to next part...   |