If I go with the 2 coil method, how schould I dispose them, values ? How is it possible for one coil to sense the diameter? Any website that describes a simple coin acceptor? I plan to build a toy not a commercial product, so there is no problem with fake coins!! Thanks a lot Javier ----- Original Message ----- From: Anthony Ryan To: Sent: Saturday, April 07, 2001 9:46 AM Subject: [PIC]: Inductive sensor & Coins I fix coin acceptors all of the time. Coils are arranged to measure the thickness, diameter, and material (2 measurements) content of the coins inserted. A value is obtained for each parameter which is then compared to values stored in non-volatile memory. If the value is within the "windows" stored in the memory, the coin is accepted. A further piezo "knock" sensor is used to measure how hard the metal is. Currently 16 coins can be validated. If you only want to use two inductors, you will have major problems with accepting false coins. Regards BBB -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.