HDD indicator LED and using an 4N27 Integrated Circuit for 12v LEDs

[SwartHack]

Hello OverClocker Community!!!
First post here and I am newb at the modding game. I believe this is the appropriate forum for this question. I apologize if this is a rerun. If so please direct me to the appropriate thread.

So, I have learned that the mb pins for the hd indicator light runs at about 3v. I test mine and it jumps around a alot, obviously, but seems to peak up to well over 3v at times!?

I bought a three light laser LED:
http://www.newegg.com/Product/Product.aspx?Item=N82E16800888057

Cheap cool accessory I thought, not many specs on the manufacture side or the packaging though, just that it is 12v.

Hooked up the HHD indicator leads and nothing. Tried a 9v battery to test and it worked fine!?
( I have Y'd my indicator leads and tested all the connections)

So not enough volts?? Right?

I then saw this:
https://forums.ebuyer.com/showthread.php/40651-HDD-LED-on-mass-Tutorial

It shows using a 4N27 IC to use the HDD indicator signal as a on/off switch for a 12v power supply. Pretty cool actually, and would achieve the desired results for me.

But I a have a few questions. The tutorial indicates the possibility for a multitude of lights, but I saw somewhere that the IC has a milliamp rating limit and will burn out!???

So, what is the voltage requirements of a single LED and what milliamps?
Can I figure out how many LEDs can actually work.
What are the specs of the standard stock HDD indicator LED??

And finally, as the tutorial is a little dated:
Is there an alternative here?? Please! or maybe someone has made this into a nice little packaged component for the modding community.

Thanks for any feedback, it is greatly appreciated.

Great to be here!

Cheers!

 

[freakdiablo]

Well to get you started off, there is no definite voltage & amperage rating for LEDs. I've seen them go from roughly 2V, 5mA all the way up to 12V, 1A for multidiode lighting LEDs, and wouldn't be surprised if they went higher (the laser LEDs you linked to are definitely not in that category though).

The 4N27 does have a current limit, and unless I'm reading the datasheet wrong, it looks to be about 100mA. The problem is I can't find a spec sheet for those laser LEDs.

As for the specs of the standard HDD LED, I really don't think there are any. I've seen green HDD LEDs, red LEDs, the one in my current case is white. All will have different voltage drops across them probably varying current as well (but I doubt any of them are more than a few mA).

Alternatives? I can't think of any and haven't seen any pre-built alternatives. That tutorial is basically using one of the simplest methods out there. What that IC does is basically take the 3V from the motherboard, uses it to trigger a small IR LED inside the IC itself which turns a small photo-transistor on and off, acting like a switch. This switch then allows the higher 12V rail to flow through a separate circuit, in your case turning on and off the LEDs, without risking it bleeding back into the motherboard and frying anything designed to run on 3v only. There may be newer ICs that do essentially the same thing but I can't think of any off hand.

Can I say this will work with those laser LEDs? Without a spec sheet for the LEDs I'm hesitating to say yes. There's the question of how they're wired (series vs. parallel) the amperage rating (are they standard 10mA LEDs or something higher), did logisys cheap out and use 20% tolerance current limiting resistors (don't even know if they're made anymore, but if they are, I wouldn't be surprised if logisys is using them), etc. You can always hook up a multimeter to read an amperage using the LED strips and a 12V source, if you have access to one.

If you really want, you can try just wiring up one of the strips to start with, I'd be surprised if they'd be wired in parallel and each LED pulled more than 33mA, but for me there are too many unknowns with those strips to wire up all three from the start to just one IC.

 

[SwartHack]

Thanks for the good info freak.

In researching LEDs, its seems there are a bazillion types depending on intended use. And, yes, manufacturer specs would be nice. You do get what you pay for. Looks like I may have a little hack and error by fire on hand!

A few follow ups...

I know the difference between series and parallel, but how does this affect amperage? The tutorial shows wiring them up in parallel, right? I bought two of the laser LEDs and they are pretty inexpensive, I may just have to bust one open to see.

I have a multimeter, and a 12v power source. My psu. If i just hook up the laser LED as designed to a standard 4-pin molex power source, how do I read the amperage? Can i just test off the two pins where the LED is wired into the manufacture's molex wire harness ? I have never really used my multimeter to test amperage, I assume it is the DC mA settings. I have .05, 50 and 250 range settings, I would guess to use the 250?

And, finally, it seems there are a number of different types of 4N27 ICs:
http://www.newark.com/webapp/wcs/st...N27&pageSize=25&showResults=true&pf=810074239

I am guessing the Forward Current If Max mA rating is significant and I would want the 100?

I know you can't guarantee this wont happen, but in a perfect world right, during my hack and error playing with this, when I do make fire, I assume the chip will burn out before any damage to my mb.

Salud!

 

[SwartHack]

OK, WOW, I am a little brain dead mostly.

Did I just find the best replacement for a 4N27!! I totally missed this on the website:
http://www.newark.com/webapp/wcs/st...N27&pageSize=25&showResults=true&pf=810074239

The 100ma is definitely a newer chip. The Suggested replacement for:4N27, NTE ELECTRONICS NTE3040.

At a unit price difference of .33c to $2.41, there must be a significant difference??!!

 

[noxqzs]

I would assume that the LED's inside your light are wired in series. If you can open the box up, you could rewire the LED's in parallel and be able to drive them without any extra ICs.

 

[SwartHack]

Follow up and what I have learned!

Ok! Brace yourself all you pinheads, byte counters and wannabes. I have finally returned to bestow upon all what I have learned, as is my civic duty to the OCC!!!

Sorry for the delay but as you will see I have been busy on the bench...

DISCLAIMER - Nothing in here is knew information, it is all recycled. I have just applied it with my style. I was actually reading posts from 2002! Modders in the UK where using them back then.

So where do we start, I have so much info, and pictures even.

ah, of course with the chip, aka: the integrated circuit or IC, the optoisolator, the optocoupler isolator, the optotransitor. Depending on who you are talking to. It turns out there are literally 1000's of types of ICs that are optoisolated transitors. The one from the tutorial link in my original post was a 4N27. I could not find this chip and learned the 4N25 was basically the same chip, then found out that the NTE3040 was the replacement!?!? huuhh

So, whats the difference and what limitations does each chip present?? Well if you compare the forward drop current against the V(BR)ECO, and compensate for the VCEO saturation loss along with the delta of the IR, then you can determine the capacity of your cooler and how many beers you need to take camping, ha ha got you...

No seriously, some guy said something like that to me like I was supposed to understand. I was at the counter of some local twilight zone electronics store looking for the 4N25, which I actually found there. But that is another story...

So the 4N25, which is actually part of a series.
http://www.farnell.com/datasheets/1809732.pdf

And the NTE3040
http://www.nteinc.com/specs/3000to3099/pdf/nte3040.pdf


In my current rig that I am using, I used the 4N25. I have not tried the NTE3040 yet, more on the rig later.

So if you check the specs, what does it all mean? Here are the numbers to be most aware of.

If- forward current
Ic- collector current

indicate the max capacity you can hook up to the 12V side. The LED laser lights I reference in the original post work great on the 4N25. I do not know how many milliamps they are pulling, but more on that later. Basically the higher the better. There seems to be some confusion between them for me, not sure which one is the actual limiting factor.

Vf - voltage forward

This is the one that threw me. This is how much voltage the diode side of the chip basically loses, so the end result is my 12v stuff works great, but the original HDD led basically dies and you can barely see it. More on this later...

So, you can go over the specs and learn all the symbols and what they mean, but basically the difference I see right now is about 2$. Supposedly NTE just buys the chips, stamps their name on it, individually packages them and marks them up 2000%. I don't know yet but will report if I see a difference.

So the Chip Rig Hints and Tips
I took the idea from the original tutorial and applied my hack to it.

First off, use a socket for the chip. You can solder on the socket and not worry about the chip. you can also change out the chip if you happen to fry it. Plus it also looks cool. Be careful, first time I melted the pin right out of the socket. Also make sure to heatshrink right after soldering as the socket pins are delicate and this greatly reinforces them. Get the smallest shrink wrap you can find.

The socket has pin numbers as well and you must match them up to the chip. The pin 1 on the socket is upper right when the small cut-out is oriented to the right. (see pics).



BONUS COVERAGE
I wanted to be able to control my LED effects with off/on. Here is my hack using a cool LED switch. All component are modular! I use JST sm series connectors. I just ordered some black ones.


I also have the LED strip but it is not controlled by the chip, it has six modes and oscillates between them automatically, so I have it just wired to the switch. Between the Laser LEDs and strip you get a really cool effect. And you can turn it off/on with the flip of a switch.

Limitations!!!
Integration of the chip basically kills your stock HDD indicator! I tried to plug it into the 12V side and it blew up, so onto...

LED Voltages and Milliamps
I am basically not much farther along this road as I was except to say I have a brand new variable bench test power supply. I plan to hook this thing up and blow some stuff up

The voltage off the HDD indicator seems to vary for each vendor/model but stays between 3.6 and 5 I believe. I have Y'd my HDD indicator in an attempt to run the chip and the original HDD led indicator. As I stated this failed. I tried to plug into the 12v side and blew the LED. I have the HDD Y as a parallel wired component, I have not tried to wire in series and do not know what will happen, hence the new toy.

The Laser LED I have runs fine on the 12v side but I am still unaware of how many milliamps it is pulling, Once I get all hooked up to the bench tester I will start seeing what is going on and push it too failure.

So LEDs....
I went to the good ole RS and bought up a handful of LEDs. all different kinds/colors. 3v 20 mA, 12v 12Ma with integrated resistors, 2.1 v 20mA, etc,...... I even got an Ultraviolet LED. These are the bare LEDs with the wire leads, couple bucks each. I am going to play around with them and see what I can hack up. I will probably ditch the HDD indicator Y and just go with the chip and run a front panel HHD LED off the 12v side, unless I can figure out how to compensate for the voltage loss. I also plan to go large and try to solder an LED directly into the 12v side of my chip/socket rig so it flashes when it is working.

So here is the whole dilly-o wired up and working. I hacked my old HP Envy. My first project. I am going ground up on the next one.
So believers, I will try to wrap this discussion up once I get a hang for using the bench tester and working with the bare LEDs. Should have some pics of a new and improved rig in my new project in a week or so. Until then....

Comments/Suggestions/Complaints?

Cheers!

 

[SwartHack]

What you dont know will hurt you

Don't take it from a hack, but an actual self proclaimed amateur! This older, 2010,post answers most my questions, but also brings up many more. This guy Harvey Wilson makes me feel very inadequate, sigh... electronics are like a fine woman. I will never fully understand.

https://thedialist.wordpress.com/tag/hard-drive-activity/

Salud

 

[jackperez]

swarthack, each and every electrical component has a current rating and you’ll have to see what you’ve with your IC. It is important to note here that since your IC is a DC-DC convertor and their current ratings are very important. DC-DC convertors have a specific efficiency when you’re operating at more than or in range of 2A. You’ll also need to be very careful about providing a suitable heat-sink.

board assembly