I cannot get the power led to flash in standby. If i reverse poliarity it
will stay lit in standby but is off when comp. is on. Intel dg965wh mb. It
appears I need a 2 coloor led that changes color with polarity reversal. Is
there such an animal. My case is an Lian Li that has 2 leds -a red hdd- a
blue power. I hate coming back to the comp and not knowing is it off or in
standby.
Flathead
Flathead wrote:
> I cannot get the power led to flash in standby. If i reverse poliarity it
> will stay lit in standby but is off when comp. is on. Intel dg965wh mb. It
> appears I need a 2 coloor led that changes color with polarity reversal. Is
> there such an animal. My case is an Lian Li that has 2 leds -a red hdd- a
> blue power. I hate coming back to the comp and not knowing is it off or in
> standby.
> Flathead
>
>
Flathead wrote:
> I cannot get the power led to flash in standby. If i reverse poliarity it
> will stay lit in standby but is off when comp. is on. Intel dg965wh mb. It
> appears I need a 2 coloor led that changes color with polarity reversal. Is
> there such an animal. My case is an Lian Li that has 2 leds -a red hdd- a
> blue power. I hate coming back to the comp and not knowing is it off or in
> standby.
> Flathead
>
>
You can take two ordinary LEDs, and solder them back to back. On
some LEDs, one lead is longer than the other. You'd solder the
LEDs in parallel, connecting the long lead of one LED, to the short
lead of the other LED, and vice versa for the remaining LED legs.
That connects the anode of one LED, to the cathode of the other,
putting them back to back. When power is applied, one LED is reverse
biased, and the other forward biased.
This will look a mess, in terms of practical details, like if you
want this "assembly" to mount in a regular 3mm LED hole.
If the computer case had a "message" LED and a "power" LED (i.e.
the case has two separate LEDs), you could also wire those together
in parallel, with them wired anode to cathode, then connect that
to the motherboard. It would look like this. One LED will light
for one of your desired functions, and the other will light for
the alternate function, whatever they happen to be. If the "wrong"
LED is lighting, simply reverse the left hand end (rotate connector
180) to reverse the roles of the two LEDs. The tricky part, is making
sure the anode of one, is hooked to the cathode of the other.
So if you cannot get the old-style two legged bicolor LED, then you
can always use two LEDs and fake it at some level. Stuffing both
LEDs into one hole, and making it look good, is probably as much
work as hunting down the real component.
On 2008-07-24, Paul <nospam@needed.com> wrote:
> Flathead wrote:
>> I cannot get the power led to flash in standby. If i reverse poliarity it
>> will stay lit in standby but is off when comp. is on. Intel dg965wh mb. It
>> appears I need a 2 coloor led that changes color with polarity reversal. Is
>> there such an animal. My case is an Lian Li that has 2 leds -a red hdd- a
>> blue power. I hate coming back to the comp and not knowing is it off or in
>> standby.
>
> You can take two ordinary LEDs, and solder them back to back. On
> some LEDs, one lead is longer than the other. You'd solder the
> LEDs in parallel, connecting the long lead of one LED, to the short
> lead of the other LED, and vice versa for the remaining LED legs.
> That connects the anode of one LED, to the cathode of the other,
> putting them back to back. When power is applied, one LED is reverse
> biased, and the other forward biased.
I was going to say "What are you on about, of course the two pin
variety are readily available" but then I looked around and they
do seem to be getting thinner on the ground. Not exactly _hard_
to get, but they may not be readily available from consumer-orientated
retail outlets.
However, the more modern three pin type can be made to operate in
an equivalent manner to the two pin type with a minimum of additional
circuitry. http://andrews.freeshell.org/news/20080724.achh.pdf
shows the general arrangement. One vertical pair of diodes indicated
will be the two LEDs that make up the bicolor LED pack - you need
to add the extra two yourself.
The three pin device that I happened to look up used a common-cathode
arrangement which we will assume is the most common - this corresponds
to the left column of the diagram. You should be able to solder
the diodes directly to the leads of the LED, especially if you fan
them out a little. Each additional diode has one pin going to the
centre pin and the other to an outer pin - it important to get them
the right way around - for a common cathode device the end of each
diode with the stripe should go to the outer pin. The connections
to the motherboard also go to the two outer pins.
The working voltage of this arrangement will be slightly higher
than for a normal LED. There will be ample slack to drive the
circuit but it may not be quite as bright as it should be. For
this reason I recommend using germanium diodes which will minimise
the effect. Type OA91 should be readily available and cost virtually
nothing.
On Thu, 24 Jul 2008 10:52:14 -0500, Flathead rearranged some electrons to
say:
> I cannot get the power led to flash in standby. If i reverse poliarity
> it will stay lit in standby but is off when comp. is on. Intel dg965wh
> mb. It appears I need a 2 coloor led that changes color with polarity
> reversal. Is there such an animal. My case is an Lian Li that has 2 leds
> -a red hdd- a blue power. I hate coming back to the comp and not knowing
> is it off or in standby.
> Flathead
On Thu, 24 Jul 2008 10:52:14 -0500, "Flathead" <flathead@none.com>
wrote:
>I cannot get the power led to flash in standby. If i reverse poliarity it
>will stay lit in standby but is off when comp. is on. Intel dg965wh mb. It
>appears I need a 2 coloor led that changes color with polarity reversal. Is
>there such an animal. My case is an Lian Li that has 2 leds -a red hdd- a
>blue power. I hate coming back to the comp and not knowing is it off or in
>standby.
>Flathead
>
5 mm Red/Green Diffused LED's 2 Lead Pack of 10
<http://cgi.ebay.com/5-mm-Red-Green-Diffused-LEDs-2-Lead-Pack-of-10_W0QQitemZ190186272991QQihZ009QQcategoryZ11644QQ tcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262>
or if the case uses smaller LEDs
3MM Red-Green Bi-color 2 lead LED Pack of 10
<http://cgi.ebay.com/3MM-Red-Green-Bi-color-2-lead-LED-Pack-of-10-L203RGD_W0QQitemZ200240719677QQihZ010QQcategoryZ19 127QQssPageNameZWDVWQQrdZ1QQcmdZViewItem>
Standby led ?? 
Linear Mode
