In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Sparks-R-Fun wrote:

Depending on how brave you are you might be able to pull a regulated 5V directly from the power supply inside the PC case.  (It should be on the red and black wires from the four-wire yellow, black, black, red power connectors like the kind that connect to IDE disk drives.

I *think* most of these modern switching supplies handle a short circuit gracefully, though they probably drop the power to the PC in doing so.  If you are going to try this with kids you better short one out yourself to see what happens.  You might ruin the whole computer, as Bean has cautioned.  However, I suspect that most PC switching power supplies have over current protection these days.

If you decide to go this route, place a low amp fuse inline before entering the student board.  That way a short circuit condition above what might be safe for the PC power supply does not continue indefinitely. 

By doing this you can bypass the 7805 all together. or maybe just ruin the PC!

How brave are you?

 - Sparks

---------- End of Message ----------


You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=196187#m196282

Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com

The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2007 (http://www.dotNetBB.com)