the concept of my project is about monitoring the availability of a parking lot in a certain establishment. my problem is i dont have a circuit diagram and a trouble finding a kind of metal sensor. can i ask some assistance where to search a circuit diagram about my project and could anyone give me some idea what kind of metal sensor will i use. what am i looking for is a circuit diagram that is to count and display the number of vehicles that enters a parking lot and the number of vehicles that exits..hope you could help me with this project.. thank you!