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SYSTEMS PREPARATION QUESTIONS 2008 - 13

V. Ryan 2008

 

The diagram opposite shows a typical turnstile at the entrance to a theme park. As the customer pays he/she is allowed to enter the park. The owners want to install an automatic system that counts customers as they enter. This would allow the total number of people inside the theme park to be calculated accurately.

 

Why is it important for the park managers to know precisely how many people are inside the park?

 
 
 
 
   
ANSWER
   

There are limits to the number of people allowed to be in a theme park. This ensures that only a safe number are in the park at any one time. Also, if the park has to be evacuated for instance during a fire, the police / fire service will know quickly if people are still in the park and still in danger.

   

A PIC Microcontroller circuit or computer is to be used to continually update the total number of people I the theme park. A simple layout to the circuit is shown below.

A sensor circuit is to be used to detect people as they enter the park. Describe a simple circuit that could be used.  
 
 
 
   
ANSWER
   

A dark sensor could be used to detect people as they enter the park. As a person passes the sensor (including an LDR) a shadow will be cast on the sensor. The LDR sensor circuit could incorporate a relay which will energise every time a shadow falls on the LDR. The energising relay is detected by the microcontroller circuit as an input.

   
Draw the circuit diagram for your suggested sensor circuit in the space below
 

 

 

 

 

 

 

ANSWER

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