As I remember, automotive power is a pretty rough environment. The normal fault conditions on an automotive power system include reverse polarity, and two-battery jump starts ( >24V +++). The system runs around 13 to 17 volts normally, with plenty of RFI from the ignition, but may dip below 10V. Oh, yeah, and it's got to run at nice high temperatures in the hot sun over black pavement as well as in January in Minnesota. You power supply has to take all these lickin's and keep on tickin'. One of the worst environnments outside of downhole applications that I can think of. -- Lawrence Lile ----- Original Message ----- From: "rad0" To: Sent: Monday, March 05, 2001 4:04 PM Subject: [ot]: using a pic in an automotive application > I remember seeing talk about people using a pic > on a 12v automobile system. > > What's the best way to isolate it from the high amp > perhaps spikey car system? > > The discussionwas lost from my archives, so what > did everyone agree upon for powering the pic. > > thanks > > > > btw, my application here is to build a sensing system that > turns on trailer lights when the coresponding auto lights > are on. > > I had in mind to somehow 'sense' when the tail lights, blinker, > stop lights were on then turn on the corresponding light on > the trailer. I though I could just use a direct wire from the battery > to connect to a 'system' bus, then use solid state relays to > connect up the coresponding light. > > Is this totally out to lunch? or could this reasonably be done? > > One, I want to totally isolate it from the auto-tow-vehicle as much > as possible. And I'm not sure how to 'sense' when a particular > light is on. I thought I could perhaps use a giant diode and some > sort of isolation to bring it down to ttl so I can connect it to my > pic. Perhaps an optical isolator, is this practical? > > Two, having a direct to battery buss and slamming lights on and off > of it might be a problem. Is it? Will this cause gross surges that > ought not to be done? If so, how do you 'isolate' or buffer this? > > thanks > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.