This is a multi-part message in MIME format ------=_NextPart_000_31223083 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Original message from: Roman Black > >Ian Hynes wrote: >> >> >> Getting back to the transistor turn on/off method, I had a diode from >> the 12V battery to the regulator i/p to protect against polarity >> reversal. With the emitter of the transistor seeing the high side & >> collector to regulator i/p, I guess you could dispense with the >> protecting diode? >> >> But a transistor's reverse Vbe doesn't want to be much more than 5V so >> should I keep the diode? With diode forward volts of, maybe 0.5V & >> VceSAT of maybe 0.4V, supply=12 (nominal) & regulator o/p=8V you're >> cutting it fine with the regulator's dropout level. To keep the diode >> or not to keep it ... that is the question :o > >I can't remember the circuit Ian, can you re-post >it? >-Roman OK - it's an attached 2k gif. Hope there's enough res left to make it out. I reckon you could dispense with the blocking diode? Thanks - Ian. > __________________________________________________________________ Get your free Australian email account at http://www.start.com.au ------=_NextPart_000_31223083 Content-Type: image/gif; name="PWR01.gif" Content-Transfer-Encoding: Base64 Content-Disposition: attachment; filename="PWR01.gif" R0lGODlhlgBeAJEAAMm14f39/f7+/v///yH5BAAAAAAALAAAAACWAF4AAAL/nI+py+0Po5x0inNH 1ribvIWfx5WmOJ4OyqAsSIJwqppDEBj5DeD7rfMJd7ig8UY8FoFI5QHQg0YBusuwF8AutxcB8Rsc bpMaMLORlf6eUnXl3WjLE2l5HZ6Y4x36vLy3FzjwB7XG05aVZgiHKHiT4SNQOHSAg1X4YcalowSZ 6WRAmBg1akl6ulX52QSUmLOJROrDWbkzVedWFkrF5KVE5MkaEDxGi0uInCxVpSsMJvlqRuh7Rqds qOi4l6XNhpcWBzUoDiGmtdjWzcjbzb3OrrC8zJDqbJyTrqlJDHwP6l7skT2B1ACuCrgEUMBktBYA CrUIAbkHDx24g6AQHpqI//GoXJxQsSMSfBodYppo0prISlI2JIqQcWTEXDJTcHu5AJrKOLN0lDQ3 To0YU+cQCZkkqdAkRUPNTQkqzlO+Q42UnruyFFdTbhPJ/SDkU5nYsbOOjQWrNUm2ImjPum3LsmG8 Y+HgpWNwd94bcjTZhCQKCCVewXrnLhmH8WRJiov9UnkK5+NgwQskD2Y5SotExD4rQ9I8cUdBMl6l 2Xk4jNZoY7wQQhWmivMP047/4OJhqzWC1ExgidbUeaDVXLz1sf7FKV+/3q35QfzwljMPueqC1+1b gbICcIlhssMB6ZXdntKr77SIvYLlQOvnZse2uJ7rgURa75vOChpCMmbfKv9jtpps/JkGVjXFddLQ b8c1cyB+vOlBTUGYWeJDUVpcWCFOs62CGjGQfEahhubt1th5tVWn3R4pjuhIe9ZgAh0W1d2hzYot DvgPcA7eV8otpvQkn3ECtVFQF5rcddQ5/ghDHBkjFoZGa0pp1Y2NJnFHFZToWTmjHRw56GM2NZZI Dym1ccnGYWg4J5BMBA6HIEA5UCPQfPvRUhqAxo1m24CvhCeEF062eR9U9u0yxTybyMlMLzoG2CCj ZyiImCsPeUXMJVFkqeg6WJ6pZVwspkTBJHeVZw1dw4X0hisbgMoqiaNWRmZlQ3mzEYVXCWHrkmMA yd+hwlghbKQ63jlksUb/Ihggajg28RKkCLj0wQyccldftdoyt+2GKQgQTAngdnvIMONOSm5DxAJC rQbW7pZudqvCF4GL5vWxzanmsUCCmz19toJ1MfRLw6u0LvOCAvzia0PBBNsQJCjS7hinsr4+i1CB BN1HpygYkzHxiHV8KfCoyAQiyqxjhiqrypzGWuofLBrbKKVjGPUhMwDl7KjEhf4cm4SqhVczgujC VsvFqh1pW8VGCwl1PwgtOyyDUCMHRFaDVqkxrS5/3WojLg9Hsr1gn00iy0VX3TPSkEptcW/HXm21 nk9jHTFsvNaztm8HgQw1sXfX3bZvQlXkrdCFLwe0gNSh3bLKmal9ttnt/57bbi/hiibDgud6K264 nbsblthHfx5b6DRwvnpwqCctd46y0yc423QjO8ytGzMbtdLcIg35drWiOHzlxQePH9gwIm+iZ74G M/HbOsdtM+B47wJK7EdP/fyCY/hCM6F/L4137X7Thzdp1A+O+/UUv8Z88l+jCfan8DNvdpfxd6SR G3nXE73AvS98/7tPntzEu/T5jiTF2g2bGhQhJ9ksU2tbHPlsh702QUiC4xMfBg/BoP0h6mzLO1H9 KIe/EmaJZBQQE0tkpDyY7eZjC1RgnZZSOoXMrXwg/JX2UiM9pNlJHHyLn5YUcTzvlASF91KhCF/I wnYIBifGs9HlrJW4zf9tC3V3eN0ZRveD0XERYYCqxnY8gLmgYRFX4RLiDt1YPv8xzn24S4oOa5Yo ObikRwQMVvb2hx0ZomxFYnmhVaLYvCeGRXiCfAcf5MEUDGSGihIwGwGh96ioYas+/8rk9TQkQf/c AhlzHKADu2fBVC5KWbmjI90OmBE12EaWooDTYbIFvP3lTx2SAccuQeKRnyQRcr8ckx+C6a+hGKwM vMrIELxQqwLWkD5wY98buccoUSIpN9r8Y/yK6YgpEvF4f1niMBVZMsmV6JeXklkGv/FATB4kaKXc WYI6WL21YcpzHHwONI2SwQYVbobTnE8QUyOpPi6wmvZIKNVeAhgYGuT/gkX85jkHmSr58WE2phsn ItEJTvYQZpwSCAllPNqqeFLUerRDlDZF2Z9rZO+OMX3pMi650pzaDhU85WNPf3qaHtGSJKyJBqIm N7Kf8hGd82PZRTLjHsYwdarqgYcLnxBF+tGDhj/k6vm+ek0e8UhYDEHfIDyZyyu2bmj3JJ1bs9hW 1X1xi23cVkymIxRKuLVd49TiW6nqMt35Ukr6ihluAKvIWt6UF+60AFGZuB2vupKHP3ygV+tj0yIc lJvuzKcZEdul23Tloo8cx0dBq0vShoM9kiWcZ8Hat7DGaaw2/Y/bdBTbtQWQso3b7Qfnc1alCpeP pQwZao+L3OQq9wHSMuzqQnPrQTsJkHuQeujt0FpEfjmMBgNrgHZr0DDw5iRg3N1uCx6WsAQsc7ns ba97n1gAADs= ------=_NextPart_000_31223083-- -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.