Stay away guy! I didn’t want my bike be stolen anymore, so I made this alarm circuit.
Just wind a thin conductive string around the wheels. If the bike is moved, this string will break up and the alarm light will turn on and send out a message that your bike is moved.
Below is a video about how it works.
The logic behind is a simple Not logic, thus when the string is good, the electric current is drawn to the ground so that no current flows into the LED; otherwise when it breaks, the LED turns on.
It was fun cutting paper into a shape. Haven’t done it since long ago.