Unlike other Laser Doorway Alarms, this device combines a transmitter and receiver in one box taking away the hassle of aligning two separate units.

They may be employed in scientific studies, such as determining the migration of microscopic particles or monitoring animals.

The photoresistor I am using has a high resistance when light is shining on it and a low resistance when no light is present. Make sure the Arduino is connected using the 9V Power Adapter as power over USB might not be sufficient to power both the Arduino and the laser diode.

It has built-in support for minimizing all windows or locking the computer, or you can set it to send ALT + Pause, which you can listen for and act on however you see fit.Whether you want to scare your players or unveil a hidden chapter of the story – the Laser Tripwire sensor is a perfect solution for this! I am choosing to use a LED indicator as my actuator, but this could be an alarm, SMS text, or even a door lock. dekuNukem] admits that the 5 Hz scan rate means a sufficiently fast moving adversary might slip past the sensor, but if they’re trying that hard to see what’s on your monitor, they probably deserve a peek. If you enjoyed making this project, then you can find many more GPIO Zero guides in our GPIO Zero Essentials book!

Nominally this is used to send the keyboard command that hides all open windows, but we’re sure the imaginative readers of Hackaday could come up with all sorts of alternate uses for this capability. When the beam is broken, the resistance of the photoresistor drops and the input voltage goes to digital low.

Now try the test code again and see how the measured light level changes when you shine the laser pointer into the other end of the straw. We’ll now put it all together so that laser pointer shines at the LDR through the straw, and whenever the beam is broken, the buzzer sounds the alarm.

The LED will light and the Audible alarm will sound if the beam is broken, whether that be intentionally or potentially spiritual or paranormal activity if there is no human presence near the device when it triggers. They can also be used in the entertainment industry to create special effects such as laser displays or interactive sculptures. Every time you enter a correct digit “a” value increases, if it’s == 4, the code is considred correct, otherwise the number will never be equal to 4. I would strongly appreciate any suggestions, tips, or advice, and sorry if I did something wrong as this is my first post.For the repeating loop, I wrote an IF/ELSE statement that continuously polls the photoresistor digital input.