A laser tripwire alarm is an easy DIY project that can be made with common household items. This alarm creates an invisible laser beam that triggers an audible alarm when interrupted. Here's how to build your own laser tripwire alarm at home.

Materials Needed

To build the laser tripwire alarm, you'll need the following materials:

These are all basic electronic components and can likely be scrounged from old electronics around your house.

Step 1: Build the Circuit

First, we need to build the circuit on a breadboard.

This completes the circuit. The photoresistor and buzzer are now wired to detect changes in light and sound the alarm.

Step 2: Align the Laser and Photoresistor

Now we need to position the laser pointer and photoresistor to create the laser tripwire.

Step 3: Enclose the Components in a Box

For a more polished alarm, you can optionally enclose the components in a box.

Operating the Alarm

To use the alarm:

Optional Enhancements

Some optional ways to improve the alarm:

With just a few basic components, you can build your own motion-detecting laser tripwire alarm for pennies compared to commercial units. Adjust the detection beam to cover any area you want to secure and be alerted to intrusions.