This is a multi-part message in MIME format. ------=_NextPart_000_0026_01C73A1C.FF5EB2C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Can anyone recommend an on-line crash-course in FETs ? I hadn't realised how many types there are until I had to look Attached is what I want to do. Basically the 12F monitors the battery and disconnects it from some loads when too low. An over-ride comes from another part of the circuit to stop the disconnect happening if a particular process is in progress I found a B+ disconnect here, using the BSP171, described as a SIPMOS FET in its pdf http://www.edn.com/archives/1994/090194/18di1.htm http://www.edn.com/archives/1994/090194/graph/18di1fg1.htm My problem is choosing a FET based on what voltage will work on its gate. The only other time I used big P-ch FETs was as the top half of a FET H-bridge. In that case 2 x V+ was needed to turn them on In this circuit I don't want to fiddle about making another voltage for the gate (although the 12F would be capable of that), so would like to be edumacated about FETs so I can pick one the engineer's way instead of wussing out and going bipolar with a TIP TIA ------=_NextPart_000_0026_01C73A1C.FF5EB2C0 Content-Type: image/gif; name="B+_disconnect.gif" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="B+_disconnect.gif" R0lGODlhlgE2AYAAAAAAAP///ywAAAAAlgE2AUAC/oyPqcvtD6OctNqLs968+w+G4kiW5omm6sq2 7osC8EzXtgvIlO7xd5dL+H7EyrCITCKPyqYzwnxKp9Sq9RS9arfcLjfrDfccOR3PNywHDWCxe5dp B6Jlhlz+wIfXoWNdSKOHIVhFiJBmSAYolBbz9kiSCAc5pyQpCYE2uXhG+YG5AQrlKVrSeFiJ6rm6 gyfTmFiaR2p5IZtpm3qoxhq6elsEvNmgqap7bOfbmyQ8Ett8Az06a3GnvBz8dEnbIo39regU+4sD bu4oXk1+zk7pDZTL3T6/10So9vf2Ts9vsg/fz1jAgdoKEkR2MOGPfxyKsZnD64CZh/jY/OHT6UxE /n8KOxJheG0gSI8kqYV7IWgkDJUlWy4Kx3JUp14xXdrENcVQTQ07b/pU0FPdMClBfxpNCfShsZkv T0ooKtSoVBZQJ+i0UnVqy6zTrMbhGVWr2EH4yq5hWkOj2bVs21Y0CdTt2rF04zkF2MfI1711+0bK JDew4MFzo/k9XA5l2r+IG6fY+VaxiHyOK0PiajlzZcyaO3v+DDq06NGkS5s+jTr1grKIWXNW3XGi 0kqyHc42U4fpK16vVfXe8hu28C7BhxvHejzv7NsQl0eMXLy0tbDJwP6KnJzV7o1k+FRnLnA6X7FM ygfi6E4vQhDbsJAnzDox48u1UJ2S+Am+eYuU/qPb6PmPf3ZlQ50zT9m32noHCTigPvVJ5EdT84nG YIFiQIZTXHRkOIh0BqlHXzfZffggiA6KOKI9JA51YYqxrXhgei4SxGB7j1Q4o3tELZhjQv7hqGOP Af24C2XgACmkgenwmGQ/4lHFHTHLINkkexwuqV2VLsmmoHxXFaLlVlR8OWaYJSEFIW4XnfWckd/F WKaZHlVIZk5yzhmnVx2OB+edTEKEGUYmDlpkFuP4eeSVKrKo556IkvQkXsLUSSijj9K40mJKXjpV UFVNyhanNpmFIg7xiYpqo6muWupEXN4WREb4Uclqrbbeimuuuu7Ka6++/grsF8sF+413rd1H/myx 2NXlmmO0zhlrKhcB6sdZzfFHkUXSWvvbq3Q9i6cuskq7lLjbmtvcuLmCm6yL7LY74rvwJifvvMbV eyZ+d+nLr0DJ4gspI6+8ZNt6AGPapZRwqfpmg9fZ+xgjfTZsLDKRWujGqVYmxTFKFffwMXEhz6Jx SPcVvCl5AhsLVYDyxOjyaiGDdHCp/g5r82Qvf+QwXglLzByywsUc4hJxQdixKUPBsqVk6J1odL+2 1fwnVRMWTeAuSEuYX2GeAYgO1FlbujEUKNO21VVMn7dO1Bo2nHIea+bGNcIyYs0zv8jS7OHOGcun cL/a3px0z1+TQjWGC0+coHWjEYmxF4p7/qzfsqBBXmk9OUMM99gM/70554W7nTlxgIve+KJkS346 6nXnHbmwrsNeIuOgz24YlqvLjvt/MHaFd+9O105MqC0K77vuT41sOvIzYD6k85qqLpL0z/9OD9Wr Qh+99cMzE57gtOVDPkbWZqtmxN63PrZDEZI7brTZpqt32OuvwL2T94f+Oul+7/+0wH1PgP8D4NVS x7/O3ciAKhCPm1aClgIysA+BAc/z2gQf5EwweTvanec2OEDiLU55IGQf+DxIuxKa0H+KIqEK8SeT BAlNX5RqIfVeaLU+FWwm7gOeD7GHwyABUYEiDKIQXbgvJBpRaXZCIRF/aMMlHrCIBHTi/hOvKMWN RfB6OBuh7X7WRS9msXQ0FF+mwljFz1lwdGNUXxJD8UBHfRGKamzjERGoHJ/RcY98tGPc8HhDO3hN j36cXgKPV8jcrbCBU0xkCN14Rp05koNQahkFLTdJfxgPCyXT5CYzeSHmMRGC2gMlF02JylQman5o o0i15ic/MKryW95Bw/kIpq30zXKXvOylL38JzGAKc5jELKYxj4nMZKImSsocjreaeZxSco6ZzCIf NFtRuWxqc5vc7KY3vwnOcGYzRdSkpaAaI012QCOdZvwWp3ATtIEdIyOumlVt5Dm++rATkn7iUvyc g0t1qQuNaYljp97pnPN5a1pKiZYt/rf1zFrt83IG3dVEr3mFi2IUTBuNZkc9+lFnhlSkI4WNRttR TsJRazuxSimvTqpO8U2LZXWDqZjkVjnAcHNLbjqZv/bzzopi0UZptOI8DDUrqdUUVREVYzudStA+ lpSRcoSb+djYvzlmTKgvVIseIoXPYV2MjCIT5yDTZNa0qnWtbG0rOMMntQo67jqirGoXLTnKBdrF pYNa21M/way3ZdV+kgyeVhtytMGptGwqK9QMc9hI1k2CaEa1q1SAulh+5lGvVuHqXOtosmEw9K97 cI1pMUnYzYothYetxnMOtJ8tmjSAq12IIDdUWFnKFEFT2uYjx3A3z1XssaqFC2YD/rZIQmqOdBE8 26PARltEtg+XpJUTdP94O+EmtrpkOWtmrptbzn4QW4AMb3duOdjuHVK5kmWhVBH7Q/PYtLVmJCp2 2zveKAK2FTiTLY0EUz9YyfW+y80vVNmbtLBaDLmV4or2gvNKxXI3JKF5sATZltSfpvYzFg5uAwc8 z/CA2HCd6bBh71g4v0ZVt0UtcdvES9V9XTW9pZjvKU+M3xi3+I2Zfa+ztDFOD2sWqweucd8C6WMN QrZ4OT2wk3+sRB43b8nIy1+SOUpl4VlZv7yDofW2/GQle1l6YJZyl3Vc5SGGuYlZ7l2Zd3zmIePu zUQuMJq1rGYsamEkbUlzlNfc/sHHdNJ1dC6vnWNQV4gVusdTDuai07tnYj6a0ZGW9J/1nNFiRse+ MOalgDgt3V9+msTAOeamfaTpS8cUmKOumqgDrb9Uq3qVwpz0lCw962LhGsnZ2zUVUerrE9rN0Xk2 h42rBD3nZmmYyYbO0erJSnxK+1r+ZSyrSdRDTrByjf5E15192Wyh1oa89AMU0sLqWfjWuti0Jnau sXHsJt3Brd+8NbO5bFuaBNvQ3+Z3dq8NaGub+dDgxndk/R3qVwccuPRtNMAHfsp0xjtJ06k2DC2e 8IJTg6/qwzjBldltRdbw3e42t7AbrkiM0omsBkbmyiuLYZXnCeWUvObLQXty/pvP/MqG1Dmbad5z aN4c6DH3OWDq59MAAx1IE0eo7VjKH/ele+S8TiaalA4e3AKa6R+9ekWq1dxEs3jFrG3m0HledKHv 3OD53ujZ2Z5yo7N7wjLzLctlDWu00x3hfMf73MmO6cDvveR/Hzuk4dz3fcOO6nofvOEB7nFHRJ7S RBzrwjVucpFj07LUgvjhTVlxx8/nHmKvMxqbzioHlr7Nnud3RVG/Pbin/fKPp7zVZU903INCFLBP leXjkO6l8+nuIMc9zBH/edPTft3Lv63Aad/Nqa747ZGUfuuL22nrK//gpvDuZ7W/fQL3W93gT7x5 1zv88oseweOnsPrXT/7fZLr//bVvyOrPT3/uO4Pjec1/dDmJWhvmfzg2gK1RgIdzgJrRewn4fAzo gLdnew+oD7ekSwo2MPCkSxK4bPATdQoWNPYUfBqYaRY0UEiXS/AngimogivIgi3ogi8IgzEogw9Y AAAAOw== ------=_NextPart_000_0026_01C73A1C.FF5EB2C0 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_0026_01C73A1C.FF5EB2C0--