How to Turn a Laser Into a Motion Detector

Assembling the Motion Detector

• 1

  Lay out all the circuit components according to the circuit diagram on the bread board. Check for overlapping circuits, short circuits or incomplete circuits within your layout and rectify the error. Make sure that for polarized components, the terminals are set in the right direction for the current flow in a laser-based motion detector.

• 2

  Avoid overlapping two connections with each other and spread out your circuit as openly as possible. If possible, try to obtain a Printed Circuit Board with planned connection layouts printed on its back. This makes the process of assembly quite easier and reduces the chance of faulty or overlapping connections.

• 3

  Solder the components carefully in their order of assembly. Avoid peaks when soldering by hand. A well-soldered component must not move in its place, and the solder on the terminals should look uniform and shiny. If the solder looks dull, it might be burnt and should be replaced. Take precautions not to heat up the photo cell too much as this might render it non-functional.

Setting up the Motion Detector

• 4

  Position the completed kit in a concealed position behind a door or near the floor by the doorway. Set up the 5 Milliwatts laser along with its power source on one side of the doorway, such that the beam traverses the width of the opening for the door panel. The photocell based detector and the rest of the kit can be placed on the other side of the doorway.

• 5

  Use mirrors to reflect and target the laser beam if a denser and more foolproof network is required. For a more concealed approach, use an infrared beam not visible to the naked eye. The beam must always fall directly on the photocell detector, or after reflection through mirrors, for the motion sensor to work.

• 6

  Test your assembly by passing through the doorway or simply interrupting the beam. If everything is set up correctly, the buzzer should go off. Also see if the door panel is actually cutting through the beam or not because the motion sensing works if the beam is effectively disrupted.