Hi I am a 2nd year electrical eng. student requiring clues with basic fundamentals. My project this year is working up to be a driveway detector that will discriminate between person or car at low speeds and activate an warning indicator to pedestrians and driver of collision danger in the so called 'blindspot”. I originally planned to construct an open loop similar the one you would find at an intersection. Based on a resonance or out or resonance concept. This is the circuit I was going to learn and expand upon http://www3.telus.net/chemelec/Projects/Loop-Detector/Loop-Sch.png [Broken] However as my driveway is not going to be dug up anytime soon I would have to place the sensor on the fence, vertical to the vehicle. This presents a few issues, 1.The distance from the general mass of the vehicle, 2. Heat and the effect it will have on the stability of the circuit (direct sunlight at times of the day) 3.The actual size of the loop. I understand the ratio of length to width will limit the detection distance. One of my tutors suggested placing a parabolic dish behind the sensor to see if we can extend the field. This will make it very unsightly. After some research I stumbled upon the “probe” version of the loop detector. More compact, better range, can be buried beside an existing drive way – perfect just what I assumed might be available just took longer to find it! Example of this http://www.gatedepot.com/prod_emx/broc/carsense_101.html [Broken] Can anybody tell me more about this device. Dose it use the same principle? Is it just an electromagnet? Would I need to find an alternative detection circuit, core types wire gauge, circuit diagrams or suggested papers or publications. Any suggestions will be much appreciated. My project is supposed to be about 200 hours, research, marketing plan, design and build included. I still have the gate detection and power circuits part to go after this! So I do not have to much time for build and fail. any and all feedback and suggestions greatly valued.