On Sun, Dec 7, 2008 at 8:38 PM, Bob Ammerman wrote: > Solarwind, > > I am not sure if you properly understand this, but you can't 'add another 5v > regulator' to an existing 5v output. All regulators (except step-up > switchers) require an unregulated voltage greater than the desired regulated > voltage. You *could* add a 5v regulator to a 12v output (like on a disk > drive power connector). > > As scary as it sounds, using a USB port to get 5V is *probably* one of the > safest ways to get 5V (or thereabouts) out of your PC. You should almost > certainly be able to draw up to 100ma without any trouble whatsoever, and > can most likely draw up to 500ma (at least on a desktop system). On the > other hand, most USB ports are protected against short-circuits, ususally > with a device called a "polyfuse" (tm) which is *not* an ordinary fuse, but > rather a device whose resistance *temporarily* jumps up if it gets hot > because too much current is flowing through it. When the short circuit is > corrected and the polyfuse cools down it goes back to conducting with a nice > low resistance. > > As a quick aside: I want to wish you the best as you move from the calm > peaceful world of software into the rather more chaotic environs of firmware > and electronics. I hope the PICLIST continues to be a useful resource to you > as you work down this rock-strewn path. Just remember: there are no stupid > questions .... *if* the question is asked in the right way and in the right > place. In today's world a quick google or wikipedia search is often a good > idea. > > ---- > Bob Ammerman > RAm Systems Thank you. I'll use the USB port. -- ..::[ solarwind ]::.. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist