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LED Device lights

Posted on 1998-07-17
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Last Modified: 2010-04-27
This question is probably aimed more at electronics gurus.
I have a server case at home that I want to use all of its features, especially the led lights.
The server case has 6 individual led lights for different devices. Currently, device 1 is my first IDE Hard drive. This first LED connects to the motherboard and tells me when the hard drive (C:) is being accessed. My other devices obviously have lights on their front panels, but not the hard drives.
How do I get the other LED's connected to my other hard drives, both IDE and SCSI?
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Question by:datn
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18 Comments
 
LVL 9

Expert Comment

by:rmarotta
ID: 1137413
datn,
I think you may find that the LED connected to the motherboard indicates all hard drive activity.
Each Hard drive would need to have header pins for connecting its own individual activity LED.  Many drives have these connectors.
Connect each to its respective panel-mounted LED.
Lacking such a connector, you might remove an on-board LED, if the drive has one, and connect yours in its place.
Documentation can be found for most drives at thier manufacturer's websites.
Regards,
Ralph

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LVL 17

Expert Comment

by:mikecr
ID: 1137414
Ralph is correct, most of the newer hard drives don't come with an LED connection and the motherboard takes over by showing a flashing light no matter what hard drive is being accessed as long as the HD LED indicator is plugged into the board.

Mike
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LVL 2

Author Comment

by:datn
ID: 1137415
I'm certain that the LED off the motherboard only is for the first hard drive. I ascertained this last night by doing stuff, like copying files back and forth from SCSI to SCSI and 2nd IDE to 3rd IDE Hard drives, and the light for DEVICE 1 on my case didn't turn on. It only turned on when I specifically did something with the C: drive.

As to the comment of the correct header pins, does that mean that I have to modify stuff off the hard drives themselves or can I "patch" into the power leads off of the power connectors?

Each power connector has a 5V, 12V, and two black grounds.  Would patching into any combo of these help? Would tapping into these leads cause the LED to be constantly on?
0
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Expert Comment

by:SirCaleb
ID: 1137416
ok...if the LED is only lighting when you access C:, your motherboards capability may not to activate the LED for all HD accesses.  What is your Motherboard model/make?
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LVL 2

Author Comment

by:datn
ID: 1137417
As a clarification, I am not trying to connect the Device LED's on the case to the motherboard. I am trying to connect these LED's to the actual Devices themselves.
It seems silly to me to have these LED's on the case and have them do nothing. All the other devices, CD-ROMs, Tape Backups, CD-Writers, Zip drives, etc. have LED's already. So, I assume, that the LED's on the case are for things like hard drives that don't come with one. I guess maybe I'm asking a little too much from my computer?!
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Author Comment

by:datn
ID: 1137418
In addition, the reason why I want to connect it to the power supply is because, after opening up many devices with external power supplies, I notice that the LED is coming off the power supply. I also have noticed that many of these external devices have corresponding internal devices that don't have LED connectors. This is why I thought the power supply connector might be the answer.
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LVL 17

Expert Comment

by:mikecr
ID: 1137419
Under no circumstances should you try to patch the LED's to the hard drive power cable! If you do, you will probably either A: burn out the bulbs or B: your hard drive will have problems because your taking power away from it. If you motherboard/case/hard drive don't have the adequate connections to plug into then I would reccommend leaving well enough alone. I'm not being mean or anything, I've seen so many problems occur because people want to rig something to work because it looks good but doesn't provide any actual relevance to the system's functionality. This is only an opinion so take it for what it's worth.

Mike
0
 
LVL 2

Author Comment

by:datn
ID: 1137420
Thanks to all for the advice. I just talked to an electronics person that says it can be done, just a lot of work.

For those of you who are curious, the 5V connector and a ground is needed. This would have the LED on all the time when the computer is on.

It's much more complicated if you want the LED to turn on only when the device is accessed. A separate ground, like off the hard drive motor, would have to be "tapped".

As for functionality as mikecr questioned, I think it would be great to have an indicator light to see if the device is even getting any power without having to open up the case. I will, however, take the advice to leave things as they are, because, this is much more complicated than this expert would like to tackle.

So, again, thanks everybody.
0
 
LVL 17

Expert Comment

by:mikecr
ID: 1137421
Your welcome Datn. Anything can be done but is it worth the trouble and money sometimes? Probably not.
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LVL 1

Expert Comment

by:spacebrain
ID: 1137422
My seagate 9140 doesnt display hdd activity on the motherboards led, theres a connector
that looks like jumper pins wich the led is actually plugged into ont he drive itself that show hdd activity. Might wanna check ont he web site of your hd maker for sucha fonction on it
0
 
LVL 1

Expert Comment

by:spacebrain
ID: 1137423
My seagate 9140 doesnt display hdd activity on the motherboards led, theres a connector
that looks like jumper pins wich the led is actually plugged into ont he drive itself that show hdd activity. Might wanna check ont he web site of your hd maker for sucha fonction on it
0
 
LVL 32

Expert Comment

by:jhance
ID: 1137424
datn,

I'd suspect anything that your "electronics guru" told you if he said that all you need it +5V and ground to hookup an LED.  You MUST use a current limiting resistor with an LED or you will pull too much current through the LED and do one of two things:

1) Burn up the LED (This is the best possibility)
2) Burn up the cable or power supply driving the LED.

An LED will pass very large amounts of current once you have applied more than about 1.5V across it's terminals.  Most LEDs are designed to operate at a current of about 25mA.  So it you are running 5V, you should use a series resistor of about 150 Ohms.  

You can calculate this yourself using Ohms Law.  If you remember (or even if you don't) Ohms Law says that V = IR.  To calculate the R, it can be restated as R = V/I.  Our voltage is 5V, but we must subtract the "forward voltage of the LED.  It's approx 1.5V so V = 5 - 1.5 = 3.5V.  We want to get a current of 25mA or 0.025A.  So our calculation is R = (5 - 1.5)/0.025 = 3.5/0.025 = 140 Ohms.  Since there are no 140 Ohm resistors commonly available and the current is not critical, we can choose the standard value of 150Ohms.

Hookup is like this:

+5V --------150 Ohm Resistor -------LED--------Ground

0
 
LVL 2

Author Comment

by:datn
ID: 1137425
Sorry JHance, already know this. That is why this is too much for me to tackle. I would rather leave things as is versus attempting to solder resistors, etc., to get a few LED's to work. Thanks anyway.
0
 
LVL 9

Expert Comment

by:rmarotta
ID: 1137426
datn,
Have you found the answer to your question?
Ralph

0
 
LVL 2

Author Comment

by:datn
ID: 1137427
Rmarotta,
Yes. Many Hard drives come with jumpers that are designed for LED's. However, mine aren't. So to get LED's, I would have to mess with the circuit board on the hard drive, something I definitely will not want to do. I am currently trying to delete this question. I was just going to let it sit for a day before I delete it.
0
 
LVL 9

Expert Comment

by:rmarotta
ID: 1137428
I thought I told you this in the first comment.
Ralph

0
 
LVL 2

Author Comment

by:datn
ID: 1137429
rmarrota, I agree. Submit comment as answer and I'll give you points.
0
 
LVL 9

Accepted Solution

by:
rmarotta earned 60 total points
ID: 1137430
datn,
The points don't really matter to me.
I just thought it might be instructive for anyone reading it in the future from the PAQ. (Especially jhance's answer)
If you want to delete the question, just go to Customer Service and post a zero point question asking to have it removed.
Regards,
Ralph

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