Hila Research Centre

Computer Engineering

Light Beam Detector

        A focused light beam makes your computerized light detector much more useful. Here is how to create a focused beam of light.



       Connect the resistor and LED to the 9V battery, either by soldering or twisting together. Tape the connections with electrical tape.

       In a dark room, shine the LED through one of the lenses (lens 1 in diagram). Adjust the distance from lens to LED so that you get a narrow beam of light. Design something to hold the LED and lens steady. (We use wooden blocks.)

       Now "catch" the beam of light with the second lense (lens 2 in diagram) and focus the beam onto the photocell. Adjust the distance from lens to photocell to produce a bright spot of light on the photocell. Design something to hold the photocell and lens steady.

      Connect the photocell to your computer using pins 1 and 3 of the joystick port.

         Test the beam by running this program:

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