🚀 go-pugleaf

On Thu, 6 May 1999 13:53:46, "Charles Wills" <CWILLS@juno.com> wrote:

:> Jim-
:> 
:> Thanks,  I would appreciate it.  Just send it to cwil@NOSPAMbicom-inc.com
:> (remove NOSPAM).  We are developing a Pentium class motherboard with a hard
:> drive built on that will plug into a card cage.  Since this board will be
:> "hot swappable" we need to be able to unplug the board from the system, but
:> only after the hard drive has shut down.  It would also be nice to have a
:> way of lighting an LED to tell the Technician that the system has finally
:> shut down, but we haven't found a way of doing this yet.
:> By the way, I wasn't able to load your web page.
:> 

How about a transistor hooked up to a capacitor controlling an LED. 
When the capacitor drains past the point where the transistor can hold
the LED off, then the LED comes on via a small battery. If you put a 
resistor in line with the power supply and the capacitor, then the LED
will not go off until the capacitor is charged enough, thus providing 
an indication that the board is powered up enough to allow other stuff
to be manually turned on.

Add a micro-switch to sense when the board is inserted (between the 
battery and the LED), and the control is complete.

To get fancy use a bi-polar LED (red and green) providing green that 
the battery has power, and red that the motherboard is in an uncertain
state.

Wojtek Bok                       "My                  WORD"
Byte Of Software Systems Inc.    "Programmers don't   BYTE"
http://www.bossi.com             "They just         NIBBLE"
wojtek at bossi dot com          "A                    BIT"