# HDD Activity LED Mod



## Ironsoap (Oct 9, 2007)

I have this idea for an HDD activity LED mod. 

Basically, depending on the amount of HDD activity, it would trigger an unknown amount of LEDs to light up, spelling a phrase.

So let's say the phrase is HDD. With a little activity, H would light up, but with a lot of activity, such as boot, HDD would be lit up. 

I don't know how plausible this would be, however, because from what I've seen, the HDD LED is just triggered by current on the 39th wire in an IDE drive or something. The only way this would be possible is if the amount of current were to vary. 

If this were to be the case, how would this be done? Would I have to program a microchip, or just design and order a PCB? What phrases would you guys suggest (my first Idea: "oh shit!; 7 LEDs").


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## kwchang007 (Oct 9, 2007)

Hmm if it's one wire, I'd think there'd be two states on and off.  Do you know if the voltage varies between more than two states?


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## Ironsoap (Oct 9, 2007)

kwchang007 said:


> Hmm if it's one wire, I'd think there'd be two states on and off.  Do you know if the voltage varies between more than two states?



No, that's why I came to this forum. People tend to know a lot about subjects with minute importance.


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## imperialreign (Oct 9, 2007)

in theory . . . if you can use a DVOM and verify that there is a voltage feed to the LED, and that the voltage changes in consistent manner with the intensity of the LED (gets brighter = higher voltage) . . . you could always snag a simple 5V LED from Radioshack or somewhere and a 100o 1/4W resistor and wire it to the (+) lead of the LED.

I mean, you'll defi have to figure out the electrical specs for the LED circuit, and then decide on a correct resistor.  Most LEDs won't even work if you drop the resistance to low.  Some will, but the light will be so dim you won't be able to see it.  But, in theory, if the voltage supplied to the LED does go higher, the intensity will get brighter as there will be more juice left over after running the resistor.

If you wanted to tack on more LEDs, wire them in parallel to each other so that they will all be supplied with the same amount of voltage and amperage, and you can then use the resistor only for the ones that you don't want to light up at idle.


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## Zedicus (Oct 9, 2007)

hdd led is not on at idle any ways.   the voltage out of the hd led circut on the mb maxes out at 3.3v (normal led voltage) and normally it just passes through the signal from the hdd pin on the drive.   it does do some extra stuff when using sata drives or multiple drives though.  if u wanted it to actually light up in a row like how an audio equalizer looks that would take a fair bit of circutry design. you would hav to pull from like a 5 volt source and use the hd wire as a trigger.


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## t_ski (Oct 9, 2007)

There are lots of guides on the net that show you how to do the basic wiring and stuff for thos mod.  All you are suggesting is a modified version of this.  Here's one mod:

http://www.bit-tech.net/modding/2002/06/23/hdd_activity_meter/1

It's all a matter of creating some extra paths for the extra LEDs and stuff, maybe having to change some minor resistances values, etc.


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## Ironsoap (Oct 10, 2007)

Zedicus said:


> if u wanted it to actually light up in a row like how an audio equalizer looks that would take a fair bit of circutry design. you would hav to pull from like a 5 volt source and use the hd wire as a trigger.



YES! this is what I had in mind. any tips or pointers?


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## Fox34 (Oct 11, 2007)

Ok easy way, get a programmable rom chip EEPROM or Eprom I pretty sure its called. Program it up(bolean/logic algebra)Basically just binary. Use and or and nor gates for the basic of it, and then for your extra like H then DD part use the gate(which I dont know the name right now) It will count basically so when its triggered for long enough it will cause a 1 on the D or DD. Ill try to get some links going here....


EDIT: here something http://www.play-hookey.com/digital/synchronous_counter.html
I could actually draw out the circuit in class and give it to you tomorrow then just hit up radio shack for the parts solder up and wa la


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## Kreij (Oct 11, 2007)

Personally, I would do it a little differently.
The HDD signal is toggled as the disk is accessed.
Instead of looking at the voltage of the signal, I would look at the frequencey that the signal is toggled and have the digital circuitry respond to that using a frequency counter circuit.
Then have the FC curcuit output whatever you want based on the input.

Just my 2 cents.


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## Ironsoap (Oct 11, 2007)

Fox34 said:


> I could actually draw out the circuit in class and give it to you tomorrow then just hit up radio shack for the parts solder up and wa la



This would make me worship you.


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## Fox34 (Oct 11, 2007)

If my teach lets me Ill do it then send it.


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## keakar (Oct 12, 2007)

Ironsoap said:


> I have this idea for an HDD activity LED mod.
> 
> Basically, depending on the amount of HDD activity, it would trigger an unknown amount of LEDs to light up, spelling a phrase.
> 
> ...




so you want something like an equalizer light bar but with letters instead?


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## Ironsoap (Oct 13, 2007)

Another thing I was considering was just wiring LEDs all around my the inside of my case, and wire them to the HDD activity wire, so when the HDD has activity, the whole thing lights up. How many LEDs would I be able to do this to?


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## 3991vhtes (Oct 13, 2007)

IMO, I dont think that is possible.


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## t_ski (Oct 13, 2007)

As long as you are using a relay to power the whole thing, you can use as many LEDs as you want.  Just use the HDD activity connector to provide a signal to trip the relay and turn it on.

If you did LEDs around the case, it could get messy with all the wiring.  If you did the HDD word/display, the you could probably fit it all on a blank 5.25" bay cover, or better yet, behind a piece of smoked plexi.

There's some stuff on Cliff Anderson's FanBus page:

http://www.fanbus.com/

Talks about wiring LEDs and using resistors, etc...


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