Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
pd wrote:
> On 2/8/2005 5:01 PM aberger@u.washington.edu exclaimed
> > Michael wrote:
> >
> >>"Paul" <nospam@needed.com> wrote in message
> >>news:nospam-0502052135460001@192.168.1.177...
> >>
> >>>In article <nqOdnYlqN7K2MZnfRVnyjA@giganews.com>, "Michael"
> >
> > <noemail>
> >
> >>>wrote:
> >>>
> >>>
> >>>>Is there any way to stop the power LED from blinking during
> >
> > suspend mode?
> >
> >>>>I
> >>>>would rather not disconnect the cable from the motherboard.
> >>>>
> >>>>The PC is in my bedroom and since I always use suspend/hibernate
> >
> > mode, I
> >
> >>>>find it very distracting.
> >>>>
> >>>>Abit seems to be the only motherboard manufacturer with a
separate
> >
> >
> >>>>suspend
> >>>>LED header. The solution there was not to connect to the suspend
> >
> > header,
> >
> >>>>only the power LED header. This meant I had a static power LED
> >
> > while the
> >
> >>>>PC
> >>>>was turned on and no LED when in suspend mode, which is ideal. Is
> >
> > there
> >
> >>>>any
> >>>>way to get a similar effect with Asus motherboards?
> >>>
> >>>On one chipset I looked at, they use a GPIO signal and a GPblink
> >>>control bit causes the LED to flash. Presumably this is set
> >>>during the power down sequence, making it unlikely you could get
> >>>programmatic control of the hardware yourself.
> >>>
> >>>You can make an adapter cable, to drive the power LED on your
> >
> > computer
> >
> >>>case. You would need a disk drive power cable (like one of those
> >>>"Y" cables you can buy at Radio Shack, to take one disk drive
> >>>connector, and make power for two drives). By taking power from
> >>>the +5V and ground on the cable, and inserting a series limiting
> >>>resistor, to set the current level to the LED, you can get the
> >>>effect you are after. (LED lit when computer is running, and LED
> >>>extinguished when in standby.) The Radio Shack 278-767 cable
> >>>will save a bit on the cost of the cable.
> >>>
> >>>Cut the "Y" cable, so you have an end that mates to a connector
> >>>on your power supply. Insert a resistor in series with one
> >>>of the leads - I like to do this on the positive rail.
> >>>
> >>> X---Yellow=+12---
> >>> X---Black=GND----
> >>> X---Black=GND------------------------------------->
> >
> > Power_LED_minus
> >
> >>> X---Red=+5----------330_ohm_1/4_watt_resistor----->
> >
> > Power_LED_plus
> >
> >>>How you work out the resistor value, depends on the forward bias
> >>>voltage Vfb of the LED. A red LED is about 1.8 volts . A blue
> >
> > Gallium
> >
> >>>Nitride LED is around 4 volts (values taken from HP LED
datasheet).
> >>>The equation is: LED_current = ( 5 - Vfb )/ resistor_in_ohms
> >>>For the suggested values, (5-1.8)/330 = 9.7 milliamps, which
should
> >>>be bright enough. Reducing the resistor value increases the
> >
> > brightness.
> >
> >>>(Note - I guessed at 330 ohms as a starting point from experience.
> >>>Normally, you start with the value of current desired, and work
out
> >>>the resistor from that. It just means rearranging the equation a
> >
> > bit.)
> >
> >>>The power dissipated in the resistor is related to the voltage
> >
> > across
> >
> >>>the resistor. Power = (V*V)/R = (5-1.8)*(5-1.8)/330 = 0.031W and
> >>>a quarter watt resistor has plenty of power rating for the job.
The
> >>>resistors at Radio Shack could be 5% or 10% tolerance, and the
> >>>tolerance doesn't matter for this application.
> >>>
> >>>Now, one of the nice things about using +5V from the drive
> >
> > connector,
> >
> >>>is if you accidently reverse the + and - leads on the LED on the
> >>>computer case, you won't damage the LED. If we were to use +12V
and
> >>>GND as a power source, if the power source got reversed to the
LED,
> >>>then in theory the LED could be damaged. It seems the average LED
> >
> > has
> >
> >>>a 5V reverse bias rating, and so by using the +5V supply and a
> >>>limiting resistor, there is no danger to the LED on the computer
> >>>case.
> >>>
> >>>You may find that the leg of a 1/4 watt resistor, will fit nicely
> >>>into the hole on the Power_LED cable. In which case, you can draw
> >>>the circuit like this:
> >>>
> >>> X---Yellow=+12---
> >>> X---Black=GND----
> >>> X---Black=GND-------220_ohm_1/4_watt_resistor----->
> >
> > Power_LED_minus
> >
> >>> X---Red=+5----------220_ohm_1/4_watt_resistor----->
> >
> > Power_LED_plus
> >
> >>>In this case, the current to the power led is (5-1.8)/440 = 7.3ma
> >>>The advantage of using two resistors, is if you select the
> >>>resistors carefully, the legs on the end of the resistor will
> >>>plug right into the Power_LED cable. (Snip off excess lead length,
> >>>so about 1/4" is left on the end of the resistor, enough to plug
> >>>into the Power_LED cable.) I selected the resistor value, based on
> >>>what I could find in the Radio Shack online catalog.
> >>>(Part number 271-1313). When you are at the store, examine the
> >>>diameter of the legs on the resistor, to make sure they are small
> >>>enough to fit into the holes on the Power_LED cable. (1/2 watt
> >>>resistor legs may be too fat to fit.)
> >>>
> >>>Make sure everything is wrapped with electrical tape. If you want
> >>>a real professional look to the project, get two sizes of heat
> >>>shrink tubing. Smaller tubing can be slid over each individual
> >
> > resistor,
> >
> >>>to prevent the wire ends from being exposed. A larger tubing can
be
> >
> > slid
> >
> >>>over both resistors, to hold them together and make them more
> >>>rigid and easier to plug into the Power_LED. Apply a gentle source
> >>>of heat to the heat shrink, to get it to conform to the objects
> >>>underneath. Never touch the source of heat directly to the
plastic,
> >>>as it could get burned. You have to hold heat shrink tubing pretty
> >>>close to a soldering iron, to get enough heat to do the job, and
> >>>it is difficult to do it without touching the plastic to the iron.
> >>>It takes a bit of practice to get good at it. A heat gun with a
> >>>concentrator tip on it, might be a better way to do it, but I
> >>>don't own one of those. (Radio Shack 278-1627 is an example of
> >>>heat shrink A.K.A polyolefin tubing. I prefer the transparent
> >>>tubing type, as it is easier to see what is going on.)
> >>>
> >>>Under no circumstances allow +5V to touch GND. An ATX power supply
> >>>can pump a lot of current, and you could either get burned or
> >>>start a fire. That is why I've enphasised the use of insulation
> >>>in the above paragraph. Make sure there are no exposed wires when
> >>>you are finished. You can use Ty-Wrap nylon retainers, to hold
> >>>the finished cables in place inside the computer, and arranged
> >>>the right way, they might even be used to prevent the resistor
> >>>legs from falling out of the Power_LED connector. Radio Shack
> >>>278-1656 is an example of some cable ties you can get.
> >>>
> >>>I think just unplugging the cable is easier
> >>>
> >>>Have fun,
> >>> Paul
> >>
> >>Thanks for the very detailed information Paul.
> >>
> >>I think you may be correct about unplugging the cable is easier
> >>
> >>Michael
> >
> >
> > Another option which may be simpler is to make an adapter from the
> > existing LED cable to the drive power cable, or to a spare 12 volt
fan
> > connector on the board. On my Antec chassis the front panel cables
for
> > the lights and buttons are all separate twisted pairs that plug
into
> > the motherboard. Just remove the one for the front panel LED and
then
> > you can refit the end of the cable with the correct mating
connector.
> > It is relatively easy to put a series resistor in the cable.
> >
> > Arnie
> >
> On the other hand...If you just want to eliminate the blinking light
> from bothering you when you are trying to sleep...a half inch square
of
> the "Handyman's Secret Weapon" should do the trick.
> Time: 3 seconds
> Cost: $0.001
> Results: instantaneous
Yes, that would work as well.
arnie
)
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