ploppybax Posted August 11, 2005 Report Share Posted August 11, 2005 Hi all,what iam looking for is some circuit ideas for a system that alerts me when an object is say, 2 meters from the detector, i was thinking of some sort of RF generator that 'missed' a signal when the 2 meters distance was made, causing the detector to alert.the transmitter as such needs to be powerless? is this possible, i know that it can be done with car ignition systems where the voltage is induced into the coil...can the transmitter store a small charge when close to the detector then when its out of range set the detector off.I hope i am getting my idea across please help!! any ideas will do... Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 11, 2005 Report Share Posted August 11, 2005 Hi Ploppy,Welcome to our forum. ;DStores anti-theft systems use a powerless tuned circuit of a printed metalic coil with some stray capacitance as a proximity detector. Their sensors near the doorways seem to be huge and their range isn't 2m.For your transmitter to be powered when close and store a charge to keep transmitting when at a distance of less than 2m would require them to have an expensive super-cap or rechargable battery. :( Quote Link to comment Share on other sites More sharing options...
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