Kev,

On Fri, 17 Sep 2004 11:25:43 +0100, Kev Pearce \(kevp.com\) wrote:

> So with the 7805 if the input were nearer the output it would disapate less
> power (makes perfect sense really!!) but not too near as you to achieve as
> stable a 5V as possible. I'll add a larger heatsink I think, one of the
> laying down ones rather than the standing up types - just like my dev board
> has! I guess I could drive any larger outputs from the 12V input rather than
> the 5V but in an automotive I don't want to use the supply voltage without
> some form of regulator.

Just remember that "12V" in a car is nothing of the sort!  13.2V is the "norm" while running, but can drop to 
8V while the starter is turning over, and can reach 18V if there's serious battery charging going on.  Make 
sure your regulator can handle the latter, and/or that your circuit can cope with being a brief voltage drop  
if the regulator drops out during starting.  Also make sure you noise-filter every cable that connects to your 
device - the Automotive environment is very electronics-unfriendly!

Cheers,


Howard Winter
St.Albans, England


_______________________________________________
http://www.piclist.com
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist