Most home security systems are subscription-based. This is problematic if one falls on hard times; they may be forced to forgo their security to save money. To solve this problem, we wanted to build a low-cost security system (without subscriptions) that could be used by those who do not want to pay for expensive services. As college students, we found this idea appealing, being a cheap method of protecting belongings in the dorms.

What it does

The system uses a motion control sensor, which detects the presence of anything that radiates infrared light within a certain range. When motion is detected, the owner of the home is notified and an alarm is triggered to deter burglars. The system can also be reset and disabled remotely by the owner using an app.

How we built it

The app portion of the project is built using Dart, Flutter, and Firebase. The sensor portion of the project is built using an Arduino, a PIR motion sensor, motors, and a computer which facilitates communication between the Arduino and the backend services. App and sensor state are synchronized using subscriptions to the Firebase Realtime Database.

Challenges we ran into

Finding a way to push the button of the air horn with weak motors was challenging. This was was where we spent a significant portion of our time. We also had difficulties getting the Arduino WIFI module to work, and we ended up using serial communications with a networked computer as a quick solution.

Accomplishments that we're proud of

  • Created a cheap home security system that could deter criminals and notify owners immediately
  • System can be controlled in a fully remote manner
  • System is easily extensible by adding more components to the Arduino

What we learned

  • Learned about Firebase Realtime Database and how to use Firebase Cloud Messaging to deliver push notifications
  • Learned about the ESP32 WROOM
  • Learned about wiring circuits

What's next for Big Transistor Security

  • Adding more sensors (laser tripwires, sound sensors, etc)
  • Replacing computer with Arduino WIFI module
  • Adding more app features, such as user logins
  • Turret (Aditya's Idea)
  • Using actual transistors :)
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