Items Used - leesm5/Wireless-Bluetooth-Security-System GitHub Wiki
2x Arduino Uno ~ $25
The Arduino Uno is a low cost microprocessor that has many libraries that can be accessed. It is a good place to start for new programmers. It is recommended to be purchased from arduino's official website to be certain it is genuine. Two were used in this project. A smaller arduino could have been used however two unos were already owned. They can be powered by an AC-to-DC adapter or battery. There are 14 digital input/output pins. It has a 16MHz clock speed which is more than sufficient for a small project like this.
433 MHz RF Transmitter and Receiver ~$4
Allows wireless communication between microcontrollers. Both require 3V - 12V with more voltage increasing the range. The arduino 5V port works for these devices. An antenna can be added to the transmitter to increase the range. The range at 5V for this product is tested to be ~6 meters.
HC-SR501 PIR Motion Detector ~ $8
The HC-SR501 is a low cost passive infrared motion detector. It detects changes in infrared light and outputs high if motion has been detected. A range of 3-7 meters can be adjusted and is suitable for many projects. There are only three pins that need to be wired. They are power, output, and ground. The power connects the 5V supply on the Arduino Uno, the Output connects to a Digital Input, and the ground connects to GND. This device also features sensitivity adjust that changes between 3-5 meters and time delay adjust, which changes how long after detection that the device will start to detect motion again.
For this project, the motion detector is set to repeatable trigger. This means that when the motion detector detects motion, it outputs a high for for a predetermined amount of time. In this case, four seconds. During this period of high output, the detector will continue to detect motion, hence the trigger is repeatable. This allows to motion detector to continuously output a high voltage when motion is continuously happening, like someone moving in a shower.
After motion stops being detected, there is a three second period when the motion detector does not detect motion. After this period then it will detect motion again.
A more detailed tutorial of how to use the HC-SR501 PIR Motion Detector can be found at
LED Lights ~$2
Three LED lights are used. One green, one yellow and one red. Each LED anode is connected to a Digital Output pin through a 220Ohm resistor and the cathode is connected to GND.
220Ohm Resistors ~$1
Three resistors are used for the LEDs
Piezo Buzzer ~$1
A piezo buzzer is a small device that makes noise when a positive voltage is applied to it. Its anode is hooked up to a digital out pin and its cathode is connected to GND.
