This is a multi-part message in MIME format. ------=_NextPart_000_0168_01C8722B.40986AF0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit > It's possible to detect a hand or any other conductive object > at a distance of 6" by using capacitive sensing Scott, the attached circuit will do just that. Sensitivity is mostly dependant on the size of the metal plate. I've embedded these behind walls as secret switches, using 100mm x 100mm of adhesive aluminium foil as the sensor. A sensor that size will react to a hand (parallel is best at that distance) through 100mm of averagely-dry wood. Although I've described it as "touch" it's actually a proximity detector. I often have a discrete Schmitt trigger, with or without settable hysteresis points, after the op amp to get logic levels but an analogue interface could be used ------=_NextPart_000_0168_01C8722B.40986AF0 Content-Type: image/gif; name="touch_switch.gif" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="touch_switch.gif" R0lGODlhVAHPAIAAAAAAAP///ywAAAAAVAHPAEAC/oyPqcvtD6OctNqLs968+w+GGxCQhnmYqMi2 7gvH8kzX9o3nOr7uSO8LNoDCotFCPCpIPVWqVEoqK9Kp9VrNZa+3LferWXmXHkB2PJ6YH+nP2lFt g5Xyp11kJr4jdUh+secH8reU1jc3d9gEFSgTd9jxONWIyHOS4CQWRXhZCed54dQJ9QNqGgN5lHrK 2trlWgorO2u0WqTXaEu7O7sYy3sHqwvsgmJMigyXd0zGsPw2bCMlerKsqgUYPKqHHO2jQvmJ4Q1D rmNOjIeUAend9gz/fBdPX29/j3+Gnj4YJp+Maci/fe/WgVkViNMPeVsU+gnHBuKoiW5e+NI2bqGo /ot8DFrqWAgjmxB1FPEbKSTfPwr7QPpbibIfy4wnh9xy9DFnNlLUdj6E6dJmij1rWrKjgvTSxm4B xTE9xmRnH27qmu0oSbPmF6MA1TwBYosZo69dZ2ANlY5aVKVNy1YtppUG17iJ4NEVdhdVlKE81+b9 Cziw4MGEC2eF6taw4sUSsC4KK5ExRcmy5nqk7BNz5Vv1fGpS2pOWZc16i4mNafH0VdVtSWMTGXFa wMhCYwsqRdtZmdlTnboOI7paZmnCrfKg+huuV7agJ1ucZHed2rHMk++eR/0zcrzWu9cK7j38N/Aa xY4Wzzjq+RYq27t/D58e+qPGCLEeKVt3ce78/o9z3PQLgNWsV8YZrQ2nX2KJxALOgSnNF0l7tcQX nXJb8WUchFmhtV9tThE0U1IXIlHSf5U4JBMH9zm3TUHbUBfgbSGOqOBeMl43o4h3qReEizkSx4eB P6p4GWoEPoikha+8RkYmMbKoDIgvrmjFME3Ux9STZE25ZWg1aukjarA1luKQZJ4kB4EttaOaleY9 dVWRywFjUg1cHclPbhpOUs6eGfoJDZw2+olmhYQeimiiii7K6Fub+NVopMRwo6ekll6KaabSzaZp pzrd5B2emorqW3KkYnpqgkINVGl/nuLkSU9vUtlKqpba+udRaL5qp1loSIMrJnHwKhce25U6/six wCKoJbHG9WZbSGfeGK2wc0aIy7W5KlonlLp+BS2Ozcm5ISPhEhusP2LKJaSd7aJLBVGtsiftl0ru FyxRznpbql/rpftoPBwKSBHAhdr3x2feusMkHfMy+GLBr1J6GmsGl7vvohcPnDGjG5Pb8aEf6xhy oiObqTC/JRd2srZtQbqyZi1PG7OGb9Y0c1CZPhJmWcr2Qt6o2NEacFEeAoLiKTmva5ZulPqcZVoE q8r0idksNWbDQMJY3c0wLu2MviBXfZBUUV9TM9XCXinf2Ggf9K6nPS9J5HNl1wv2Lt2aSW0kfIed 9HeN5e0KZLkZUlrfitMxAhoMmWKi3xUh/ru2IbNuSznZgsd7NIZZf86szoDfO7mD9n5IVhK/klyl SA+Tc5bbdGL3qeiLwypjOGmSJHvndOX7t+9Ns2PP7d/SbKRgwNtd+zjzTuNlV+fG1vZCtLMC8Jrn bF9Iwmdj3v3D0yKm8uYqBspgQkFxYl/ouNMtOevI74gjjzw6l5+g5j6r0vX1Ucg+/72Hd/Kznd4K yALLEA4LvVMbL+KzNXoNbC3WqJv+7ge/+WlwYn2aYCcCpyP2oQ9PzxPf6UAxHfLt74TAYZ7IXjgg voBjOomTIKIWKJ57OIpQOHSVI0zYKR3uSYX+Sht0evg2IypxiUxsohOfCMUoSnGKklEf/uioiMX/ OQmLXGQWBrsIxmS0j4VhLKMZwfizM04MPv4bCgDfCMc4ylFCagSf76wUHiSaik+hqqMdm0caPf7m YoIcnh+vGME9HhKRqOiMtSBWPh/WkXCQmlX0JKnGvA3kF0Wc3SIj2auYsG1cnvwkIUsntU+S8X2K NGUjT3ceo01IQYUMJHsi574CmW5ZzQJlFpMlvD+GIn+8zGUtS7nKZD5Sc70kkQFv+UxloqqZwYxY h6JJzesNaoMe9Bw3pdmdN5ZnjrlgEzmvRLw5LpNExbvVhtBRsd2lSAzyjB89Ebizd2rBC0fS07/4 mbFagpBUA91nNacJNG+CcwTWy+Yr/h0qKR91Umsy5F5IsgczDnIOQ+gzJB9VaUOSTZSVdKJhQo45 mDTJKxNq2hUNAYLSBU0kZcNCZSgnZQ2v+RKGj2KOoXAJOa38L0Yx5YLqssNJYcoUpEZd2wfFGDCI 3o2pgBEoVQNj1av+JatapV9Cu/q7oIEVZ2IdEMyK6keuYoRoY23dVz2z0LYCMqgvk6pczVe4ux7s rXoFzyX1BsQkpjVAaGUkjSb5p8KqFVX5k6gDYboZviL0gm4bFghRGNmcENEOYvva2zZLvY7u0qxs dWtmE7klb6Lze+OJ2GUrVzWB4RB6+GNc84DCWs+mcpu5xE1eOcW1U55DtH2h6Upr/qW73gF1qY8r bQaZWEF8Zq6pZuOJaZ0IFn+2cKqSNaLjSHddBkqksIdlpkePl8ClXpO81HVZaHFrPOlasL0Xddb0 3IvNBjISa62Db2Btht6GUAuewXusYB8iNOC8FpZxna5S7UpRNbwjgHRtcG9/0tldytaF5n2wRV9y zhCfc7TbZWdOHbwSAbuxtgW+cI+IF7roAlS+BtZmmRhaU6dVaqIUhHDs2svPuM33mw4u1pCPOhzH kpLETHbxePyLuBvnt8ZGTq+DwjI0qBHZyQmkI0wz2uEWexjCbmhnmVJ20y2PWcpUywWNxdxkKpfD UFX5K0nDTGab2mS8b8ZvkQnb/qP/skTQ4oovl3dY4inD2aGbxCpn/HxQDqdZz38OBnsj7StJV/m5 kCTtgwXWYnrqcXngPe+kuzTTOHdPHZfbaZxAFVLUbpqz65XzOK1MWavBOtazPjXEiBZk+FYO1HX1 KdhwpcAIm5qhfVY1MrfLBCxVLCJZro5hEd1r9EK60pMqUKDul7Qcb7aSqj4rLA8H2XYQcNHOVhob Z2Q/3Taz1WMBy7W5hm8iPaa17M6zrreNNKzNsMmiXrF1/Y2ZH/cbswtPNLbHB1tmx3Dip1I4wH97 cTZTWhDMADNa6N1jTuO53ZG602HSCO/URvvDaj50yTvokZDHFeT5XvbIEV6lXehmfOM8n4+IhVjK MRZ3yZrWOIQuXZpxFxvmvB4iDMknS3kXvefoQXoVmc7DsZrcZH31dvWObt+SCjuH3BqUCC2sCkJ3 HdczHOnaR7VFWar97Xmku93vjve8S6AAAAA7 ------=_NextPart_000_0168_01C8722B.40986AF0 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist ------=_NextPart_000_0168_01C8722B.40986AF0--