How to Build a Laser Security System

Got a mystery to solve? Somebody's been making off with your stuff, and you don't have a clue who it is, do you? Here's your chance to catch them in the act.

You will need

  • A laser pointer
  • Some Duct tape
  • A few small mirrors
  • An L.M.741 microchip
  • A 220-ohm resistor
  • A photocell
  • An inexpensive digital camera
  • An extra small screwdriver
  • A wire coat hanger
  • Some thin
  • insulated wire
  • A printed circuit board
  • A 9 volt battery
  • A 9 volt battery clip
  • Soldering equipment
  • A pair of wire cutters
  • A soap caddy with drainage holes
  • A voltage relay

Step 1 Build the circuit Build the circuit. Center the microchip on the circuit board. Pop in the voltage regulator. Connect the battery clip leads to the regulator. Run 2 more leads out from the regulator. Pop in the resistor and the photo cell. Link the chip to the photo cell. Pop in the relay. Link the chip to it as well. Link the other side of the relay to “power.”

Step 2 Disassemble camera Disassemble the digital camera so you can access the board connected to the camera’s trigger button.

Step 3 Solder wires to terminals Look for the two tiny terminals that lead to the trigger button. Solder wires to each of these terminals and feed them through the trigger button hole.

Step 4 Reassemble the camera Reassemble the camera. If you can’t get it back together easily, use duct tape to keep it closed. Just don’t tape over the lens.

Step 5 Position circuit inside soap caddy Position the circuit inside the soap caddy so the photocell is exposed behind one of the holes.

Step 6 Connect battery to circuit Connect the battery to the circuit, and use tape to secure the whole assemblage inside the box.

Step 7 Attach wires to voltage relay Slip the two wires coming from the camera through another hole, and attach them to either side of the voltage relay.

Step 8 Cut & tape coat hangers Cut the coat hanger into several pieces. Tape one piece to the laser pointer and the others to the back of the mirrors.

Step 9 Place camera Place the camera in an inconspicuous location with the lens pointing at the object you want to protect and secure it in place.

Step 10 Position laser pointer Position the laser pointer in another inconspicuous place and secure it too.

Step 11 Place mirrors Place the mirrors to create a perimeter around the object you’re protecting, adjusting them until the laser hits the photocell.

Step 12 Test the system Now break the beam to test the system… And get ready to confront the perpetrator with your irrefutable evidence.

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