Our schematic consists on 3 elements which are: Photoresistor (LDR), Piezo Buzzer, 1 – 10 kΩ. The LDR can be connected any way you want because doesn’t have polarity. For resistance you can use from 1 ...

You can also see the USB mini-b connector which gives you access to the Arduino compatible ATmega328 microcontroller on the back. There is also a piezo buzzer for your alarm needs.