Connecting Sonata blue LEDs to fan only connection
Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee
Connecting Sonata blue LEDs to fan only connection
Anyone ever try to dim the front lights on a Sonata case? I was thinking about connecting them to the fan only connector, so their intensity would vary with how much power the computer is drawing. This been done before? Seems harmless, but I always like to let someone else be the guinea pig.
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interpellated
- Posts: 20
- Joined: Fri Jul 30, 2004 7:21 pm
Dimming the Sonata's LEDs can be accomplished with a bit of effort and a few bucks. I just finished my first-ever build, using the Sonata, and like many found the LEDs rather bright. Didn't want to just leave them unplugged, though.
Since I'm no electronics expert, I figured it best to make a mock-up to see what I could do. I grabbed a couple of blue LEDs, two resistors of similar value to those used in the Sonata's LED wiring, some fine wire, a "breadboard", and a 10K Ohm trimmer pot (potentiometer) from a local electronics supplier. I assembled the components to emulate the LED wiring in the Sonata, with the addition of the trimmer, and hooked it up to a 5V line from my old Dell's PSU. That way, if I blew something up at least my new system would be safe! Turned out I am able to easily adjust the LEDs within a satisfactory range. A suitable trimmer can be had from Radio Shack (P/N 271-343) for less than $3.
The wiring scheme is simple, although my attempt at explaining it might not make it seem that way. Normally, the Sonata's LEDs are connected directly to a 5V (red color) line from the PSU. This gives the blindingly bright light that is too much for many users. What we can do is incorporate the trim pot into that 5V line, allowing us to reduce the current being delivered to the LEDs. One way to do it would be to cut into the two fine wires (red and black) connected to the LEDs, and solder in the trimmer. Alternatively, you could make a short intermediate harness or adapter, using some bare molex connectors and pins (male and female, as needed), the trimmer, and a bit of wire (~22AWG). This harness would simply be connected in between the four-pin PSU molex and the molex that Antec attached to the two LED wires. Just be sure that you put your pins into the molex connectors so that you are using the 5V line (red) from the PSU, not the 12V (yellow).
The trimmer has three numbered pins, or terminals. Terminal #1 will be connected to the 5V line from the PSU. Terminal #2 then gets connected to the thin red wire feeding the LEDs. Terminal #3 is common, and is connected to either of the two black (ground) wires of the PSU molex. The thin black wire from the LEDs is also to be connected to either of the two PSU ground wires, of course. Now, by turning the small screw head on the trimmer, you can vary the brightness of your Sonata's LEDs to your liking, and it only costs a few bucks and a bit of time. javascript:emoticon(':D')
Very Happy
Since I'm no electronics expert, I figured it best to make a mock-up to see what I could do. I grabbed a couple of blue LEDs, two resistors of similar value to those used in the Sonata's LED wiring, some fine wire, a "breadboard", and a 10K Ohm trimmer pot (potentiometer) from a local electronics supplier. I assembled the components to emulate the LED wiring in the Sonata, with the addition of the trimmer, and hooked it up to a 5V line from my old Dell's PSU. That way, if I blew something up at least my new system would be safe! Turned out I am able to easily adjust the LEDs within a satisfactory range. A suitable trimmer can be had from Radio Shack (P/N 271-343) for less than $3.
The wiring scheme is simple, although my attempt at explaining it might not make it seem that way. Normally, the Sonata's LEDs are connected directly to a 5V (red color) line from the PSU. This gives the blindingly bright light that is too much for many users. What we can do is incorporate the trim pot into that 5V line, allowing us to reduce the current being delivered to the LEDs. One way to do it would be to cut into the two fine wires (red and black) connected to the LEDs, and solder in the trimmer. Alternatively, you could make a short intermediate harness or adapter, using some bare molex connectors and pins (male and female, as needed), the trimmer, and a bit of wire (~22AWG). This harness would simply be connected in between the four-pin PSU molex and the molex that Antec attached to the two LED wires. Just be sure that you put your pins into the molex connectors so that you are using the 5V line (red) from the PSU, not the 12V (yellow).
The trimmer has three numbered pins, or terminals. Terminal #1 will be connected to the 5V line from the PSU. Terminal #2 then gets connected to the thin red wire feeding the LEDs. Terminal #3 is common, and is connected to either of the two black (ground) wires of the PSU molex. The thin black wire from the LEDs is also to be connected to either of the two PSU ground wires, of course. Now, by turning the small screw head on the trimmer, you can vary the brightness of your Sonata's LEDs to your liking, and it only costs a few bucks and a bit of time. javascript:emoticon(':D')
Very Happy
At 12V the LEDs likely would burn out. From what I've seen looking at LEDs in electronics parts stores, mostly they are rated to be powered at 5V or a bit less. The small resistor that Antec includes in the LED wiring (concealed beneath the short length of black heat-shrink tubing just behind the Sonata's front bezel) is there to protect the LEDs against excessive current. Antec calculated the resistor value assuming 5V applied to the LEDs--at 12V you are more than doubling that applied voltage, and therefore would be forcing an excess of current through the LEDs (at least in theory, and according to my rather limited understanding of electronic circuit principles). I suppose you could satisfy your curiosity by just going ahead and feeding 12V to your Sonata's LEDs to see what would happen. If you hear a "pffft!" sound, then you'll know with certainty that 12V isn't a good idea. 
Good news is you can always get new LEDs from Radio Shack or any other electronic supply house, although the blue ones can sometimes be more expensive than other colors (depends upon your supplier, I guess). All in all, adding in the little trimmer pot is really quite simple, especially if you can do an adequate job soldering. If you don't have a solder iron, then you could probably make good connections using small size crimp connectors and pliers. The trimmer pot itself is tiny enough to actually glue it to the surface of the molex connector attached to the Sonata's LED wires. That way the trimmer wont be dangling loose inside your case, and you'll only need very short lengths of wire to make its connections to the molex.
Good news is you can always get new LEDs from Radio Shack or any other electronic supply house, although the blue ones can sometimes be more expensive than other colors (depends upon your supplier, I guess). All in all, adding in the little trimmer pot is really quite simple, especially if you can do an adequate job soldering. If you don't have a solder iron, then you could probably make good connections using small size crimp connectors and pliers. The trimmer pot itself is tiny enough to actually glue it to the surface of the molex connector attached to the Sonata's LED wires. That way the trimmer wont be dangling loose inside your case, and you'll only need very short lengths of wire to make its connections to the molex.
Someone correct me if I'm wrong...When I first connected the LED molex in my Sonata, I noted that the red wire feeding the LEDs was mated to the red wire in the molex coming from the PSU. For no particular reason I assumed that the red PSU wire was 12V. Turns out the yellow wire from the PSU is 12V, the red is 5V. I verified this with a multimeter. I would assume that Antec keeps the wire colors consistent among the different production runs of its PSUs, but who knows. In any event, your LEDs must be taking 5V (the molexes connect only one way, of course). Now, you can power those LEDs from the 12V wire, but you'd need to calculate the an appropriate resistor to add in to protect the LEDs from excess current. To figure that resistor value, you need to have an idea of the current drawn by the two LEDs. That current might be anywhere from about 20mA to 45mA, based upon the package labels I've seen at electronics stores. If I remember correctly, since the LEDs are in parallel, the total current is the sum of the current drawn by each of the individual LEDs. So in our case that total current might be 40-90mA. That would equate to a resistor value of from 300-133Ohms, respectively. Larger resistor values would allow you to dim the LEDs from their normal full brightness, which is something lots of Sonata users would like to do. That's why I took the trouble of splicing in a trimmer pot into mine. My LEDs are fairly subtle now, not irritating as they were when at full 5V.
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Tibors
- Patron of SPCR
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I took the Sonata blue LEDs and the Antec True380SP from my parts box and examined them for you. This is the result.
The red wire from the leds goes to the yellow wire of the plug. But if you connect the plug to a normal molex from the PSU, then the yellow wire lines up with the red wire and the red wire lines up with the yellow wire. So the LEDs+resistors (R) are fed 5 Volt.
If you connect the plug from the LEDs to a FAN ONLY molex, then the yellow wire lines up with nothing and the red wire lines up with the yellow wire. So the LEDs+resistors don't get any power.
I think the cheapest way to make the plug for the LEDs was to invert the molex connectors on a plug for a 12 Volt fan. This results in the strange colour scheme above.
The red wire from the leds goes to the yellow wire of the plug. But if you connect the plug to a normal molex from the PSU, then the yellow wire lines up with the red wire and the red wire lines up with the yellow wire. So the LEDs+resistors (R) are fed 5 Volt.
If you connect the plug from the LEDs to a FAN ONLY molex, then the yellow wire lines up with nothing and the red wire lines up with the yellow wire. So the LEDs+resistors don't get any power.
I think the cheapest way to make the plug for the LEDs was to invert the molex connectors on a plug for a 12 Volt fan. This results in the strange colour scheme above.