controlling Sonata LEDs' brightness using fan controller

[Techno Pride]

hi, the blue leds on the front of the sonata are too bright and annoying

is it possible to connect the wires to a fan controller and reduce the brightness? safe?

thanks for any help

[lenny]

hi, the blue leds on the front of the sonata are too bright and annoying

is it possible to connect the wires to a fan controller and reduce the brightness? safe?

Can you trace the lines? Are they powered by 12V? I removed mine so long ago, I don't remember. If it is 12V, you're fine. If it is 5V, jump directly to the last paragraph.

Provided your fan controller doesn't use PWM, it should be safe.

Even if it does use PWM, it will still be safe. It just may not be very effective at dimming.

The cheapest solution for you is just to drop by Sim Lim Towers and pick up a few resistors and splice one (or two - depending on how it is wired) in-line with the 12V. Try a few different values between 50 ohm and 500 ohms. Or do what I did - remove those suckers.

[IceWindius]

Their 12v

[OmegaZero]

Why not just replace them? Cut the leads on the old ones and solder on the new ones - not complicated at all. Electrical tape will work just fine as well, considering the negligible amount of current you are dealing with.

Any hardware/electrical supply store will have 12V LEDs. You can get dimmer ones, like 50-100mcd (Millicandela) that will work perfectly. You can even choose the color...

You can also check out Bivar's website. They have lots of LEDs to pick from. I would recommend their 5mm Standard Discrete LEDs; I currently have the blue and purple ones installed in my SLK3000B and they look fantastic. If you call the phone number on the web, Bivar will even send you out free "samples".

PS: According to Antec tech support, the stock LEDs in the Sonata are 3.5 Candela, or 3500mcd . No wonder everyone is complaining about how bright those are!!

(Standard indicator LEDs are usually <200mcd)

[lenny]

PS: According to Antec tech support, the stock LEDs in the Sonata are 3.5 candela, or 3500μcd Shocked. No wonder everyone is complaining about how bright those are!!

I think you mean mcd (millicandela). 1 candela is 100000 μcd. I checked bivar's catalog - the brightest they have is a 4500 mcd orange LED. A couple of these with a strong battery will make a nice light in a pumpkin for Halloween

Not sure if he wants to remove the front bezel (major PITA) to get to the LEDs. It's been more than a year since I removed the front LEDs - do you need to remove the bezel to get to the wiring?

Anyway, if his location information is accurate, Sim Lim Tower is less than an hour away by public transportation from anywhere in the country, and he can pick up LEDs, resistors, a bag of electrolytic capacitors, a couple of fans, zip ties, a soldering iron, some cables and a DVD player while he's there - I did

[OmegaZero]

I think you mean mcd (millicandela)

Yup. Fixed it. Sorry about that...

[LBadvance]

I just unplugged them. The LEDs on my sonata were only on for a mere 30 minutes b4 i decided to unplug them pernemantly.

[m0002a]

Too bad Antec can't put bright LED's on their disk activity and power indicators on the 37000-BQE, 3000B, etc. They are hardly visable unless you look at them straight on, whcih is kind of difficult if the PC is on the floor.

[Devonavar]

I own a Sonata. The Blue LEDs are powered off of the 12V line using a Molex pass-through. I have modded the LEDs to 5V by swapping the 12V and 5V pins in the pass-through (don't plug anything in the other end!). As far as I can tell, this mod has had no effect on the brightness of the LEDs — they're still bright as ever. I didn't try comparing them directly (not that intersted, to be honest), but I still find them overly bright even running them at 5V. I don't know enough about LEDs to say whether the reduction in voltage is just insufficient, or if they're just designed to pull the same current no matter what voltage they're fed.

[OmegaZero]

Changing the voltage on an LED will not affect its brightness. Every LED has an effective operating range around its rated voltage. While inside this range, it will light up with its specified amount of output. Outside this range it will no longer light up. See my previous post about replacing the LEDs. It is very easy to do, and allows you to choose brightness, color, and level of diffusion/focus yourself. If you order the parts from Bivar, it is a free modification.

If anyone wants I can post a write-up with pictures about changing LEDs on a case tonight or tomorrow.

[sthayashi]

A really big Rheostat may be the easiest way to reduce LED intensity. I need to play with my resistors and LEDs at some point though, just to make sure.

[ilh]

Changing the voltage on an LED will not affect its brightness. Every LED has an effective operating range around its rated voltage. While inside this range, it will light up with its specified amount of output. Outside this range it will no longer light up. See my previous post about replacing the LEDs. It is very easy to do, and allows you to choose brightness, color, and level of diffusion/focus yourself. If you order the parts from Bivar, it is a free modification.

Sorry. You can definitely dim LEDs with resistance. I've done it. Look at all the reports about LED fans where people talk about how the LED intensity changes as they undervolt.

[sthayashi]

Changing the voltage on an LED will not affect its brightness. Every LED has an effective operating range around its rated voltage. While inside this range, it will light up with its specified amount of output. Outside this range it will no longer light up. See my previous post about replacing the LEDs. It is very easy to do, and allows you to choose brightness, color, and level of diffusion/focus yourself. If you order the parts from Bivar, it is a free modification.

Sorry. You can definitely dim LEDs with resistance. I've done it. Look at all the reports about LED fans where people talk about how the LED intensity changes as they undervolt.

Changing Voltage is not the same as changing resistance. There are several different ways you can regulate voltage. The Zalman fanmate and most other Linear regulation methods will not alter the resistance. The Sunbeam Rheobus MAY change the resistance (I don't know the circuit layout, so I can't say for certain).

Ironically, PWM methods of fan regulation may work nicely for LEDs as well. Again, since I haven't tried to do this, I can't say for certain.

By simply changing the voltage you will do almost nothing for an LED, who's activation voltage is 2V or so. LEDs just provide a fixed drop with no resistance. You always have to provide your own resistors to ensure that the LED doesn't burn out. Chances are, Antec has done this already.

You are on the right track though. I believe that increasing the resistance enough will cause the LED to dim and eventually turn off.

[Tibors]

You always have to provide your own resistors to ensure that the LED doesn't burn out. Chances are, Antec has done this already.

Yes they have. But there is shrink wrap over them, so I can't tell you with which resistors. They also seriously screwed up on the wiring colors:

I once used this to explain why the "fan only" connectors don't work at all with the Sonata LEDs. As you can see they are already connected to 5V and have a resistor before and after the LED.

Thanks to ImageShack for Free Image Hosting

[OmegaZero]

Allow me to reiterate:

Changing Voltage is not the same as changing resistance.

Again, it is much easier to just change the LEDs than to create any combination of resistors, controllers, etc. I really don't see why this is such a big issue - if a light bulb in the house is too bright, do you rewire the electrical system of the building? Just change the bulb...

[lenny]

A LED resistance / brightness calculator :

http://www.ngineering.com/LED_Calculators.htm

I'm surprised that Devonavar did not see any changes in brightness when altering it to 5V. LED brightness is related to current, and reducing the voltage will reduce the current due to the presence of the in-line resistor (V=IR). Probably the LED is being over-driven at 12V. Brightness vs. voltage for LED is definitely not linear.

Edit : just saw Tibor's post. If Devonavar's is wired similarly, it means he's increasing the voltage instead of reducing it!

The Sunbeam rheostat, IIRC, is not a rheostat at all but a variable voltage regulator. Doesn't it go down to very low levels (below 5V)?

OmegaZero : you have a good point there.

[Tibors]

Probably nobody has shown them how easy it is to change the LEDs.

The top LED in the picture is unaltered. You can see one of the leads of the LED bend around the end of the connector to keep it in place. At the bottom LED, I have bend the lead straight and pulled the LED slightly out of the connector. Absolutely no soldering or fancy circuitry needed for this.

Thanks to ImageShack for Free Image Hosting

[mathias]

Yes you can alter the voltage to change the brightness. I've tried it recently with two puny green ones in series, with resistors meant for 12v, and they worked very dimly at 5v.

Unlike a lightbulb, you have to change the LEDs and the resistors, and LEDs can be a hassle to get, and you don't simply screw LEDs in. If those were green or yellow, you could probably rewire them to be in series instead of parallel. But because they're blue, AFAIK they have to be at least 4v.

If you have a spare resistor somewhere around 30 ohms, adding that would probably work.

BTW, does anyone know how many free samples Bivar is willing to send?

[ilh]

Changing Voltage is not the same as changing resistance. There are several different ways you can regulate voltage. The Zalman fanmate and most other Linear regulation methods will not alter the resistance. The Sunbeam Rheobus MAY change the resistance (I don't know the circuit layout, so I can't say for certain).

Did I say changing voltage = changing resistance? Did I say adding resistance was the only way to change voltage? I guess I should have simply said adding a resistor in series can affect LED brightness. I didn't say it was the best option, just that it isn't strictly true than an LED is either completely on or completely off.

If I recall, LED brightness is proportional to current. If you can put the right resistance in series with an LED you can alter its brightness between full on and full off. For example, here are some LED I/V curves. They are not vertical. For example, the yellow LED would have a different brightness if it had 2.2V applied to it as compared with 1.8V. If you were driving with 5V, a resistor in series of 700ohms would supply the LED with 2.2V at 4ma, wheras 16000ohms would supply 1.8V at 0.2ma.

That same article contains some circuits for controlling LED current and hence brightness. There is no doubt those are superior to simply using resistors.

[OmegaZero]

BTW, does anyone know how many free samples Bivar is willing to send?

I got them to send 6. Three different kinds, two of each.

Unlike a lightbulb, you have to change the LEDs and the resistors, and LEDs can be a hassle to get, and you don't simply screw LEDs in.

Actually, in this case it is EXACTLY like screwing in a different light bulb. If you have 3.5 Candela, crystal-clear, pinpoint-focused LEDS that are too bright, and you replace them with 30mcd, diffused, wide-angle focused LED on the exact same circuit, you will get a dimmer light source.

As I have already stated (twice), the LEDs are very simple to get. Please reread my previous posts for links and specific product recommendations.

That same article contains some circuits for controlling LED current and hence brightness. There is no doubt those are superior to simply using resistors.

...because building a dedicated circuit to make the bulb dimmer makes a whole lot more sense than just changing the bulb (for free).


PS: Anyone in the US can go to their local Radio Shack and get a standard 5mm, 30-100mcd LED in red, green, and even blue. I was there at lunch time - they had 8 different voltages available. Not as pretty as the colors from Bivar, but for <$1 with tax they are still an easy solution.

(Edited ~30 times for spelling and grammar)

[OmegaZero]

Too bad Antec can't put bright LED's on their disk activity and power indicators on the 37000-BQE, 3000B, etc.

Yeah, they are very boring too. I replaced mine with 350mcd, diffused, wide-angle purple (HDD) and 200mcd, diffused, wide-angle blue (Power). Very spiffy looking on the plain black 3000B

I also had them send 900mcd, water-clear, medium-angle turquoise (only turquoise LED they have). Very cool looking, but in the end they were just too bright...

(Edited. I wish I could type...)

[lenny]

That same article contains some circuits for controlling LED current and hence brightness. There is no doubt those are superior to simply using resistors.

Only if you want the LEDs to, for example, pulse in sync with your music Or if you want to replace it with tri-color LEDs and have the equivalent of the Ambient Orb around the USB ports.

BTW, this occurred to me.

1. LED intensity is a function of input current.
2. Current is limited by resistor, if supply voltage and LED voltage is constant.

If I replace the LED with a lower intensity LED that has the same LED voltage as the original, wouldn't I be over-driving the lower intensity LED? Even overdriven it will still be dimmer than the original LED, of course. Side effects : shortened life of LED and heat.

Granted, 9 years of 24/7 operation life reduced to 2 years is not a great loss, esp. for a 10 cents part. Still, it does seem like an inelegant solution.

Did I miss anything (e.g. the LEDs has some built-in resistance)?

Another BTW : googling has led (no pun intended) me to several articles that talks about using PWM for LED intensity control - so ignore my remark earlier regarding PWM fan controllers.

[ilh]

That same article contains some circuits for controlling LED current and hence brightness. There is no doubt those are superior to simply using resistors.

...because building a dedicated circuit to make the bulb dimmer makes a whole lot more sense than just changing the bulb (for free).

Did I ever say to build a complicated circuit rather than just swap LEDs? No.

Why do folks swap fans rather than building/buying circuitry to adjust them? After all, swapping is easier. Maybe they like playing with circuits and doing it themselves?

[mathias]

If I replace the LED with a lower intensity LED that has the same LED voltage as the original, wouldn't I be over-driving the lower intensity LED?

Probably. And that is assuming you can get one with of the same voltage; if the stock blue ones are very close to 5v, the stock resistors must be very weak, so if you got a 4v blue one to replace a 4.8v one, you'd increase the current x5.

[m0002a]

Yeah, they are very boring too. I replaced mine with 350mcd, diffused, wide-angle purple (HDD) and 200mcd, diffused, wide-angle blue (Power). Very spiffy looking on the plain black 3000B :)

Is there a special physical size of LED that needs to be used to fit in the Antec cases (3mm, 5mm, etc)? Is there a special voltage rating that I need to get?

[sthayashi]

Changing Voltage is not the same as changing resistance. There are several different ways you can regulate voltage. The Zalman fanmate and most other Linear regulation methods will not alter the resistance. The Sunbeam Rheobus MAY change the resistance (I don't know the circuit layout, so I can't say for certain).

Did I say changing voltage = changing resistance? Did I say adding resistance was the only way to change voltage? I guess I should have simply said adding a resistor in series can affect LED brightness. I didn't say it was the best option, just that it isn't strictly true than an LED is either completely on or completely off.

Sorry, I had just read this:

Sorry. You can definitely dim LEDs with resistance. I've done it. Look at all the reports about LED fans where people talk about how the LED intensity changes as they undervolt.

And thought that clarification was needed.

BTW, I was under the impression the original poster wanted to CONTROL the intensity of the LEDs, not simply replace them. Actually, I thought he wanted a quick and easy way of regulating the LED using his fan controller. Little did he know that it's neither quick nor easy to do it that way.

[lenny]

BTW, I was under the impression the original poster wanted to CONTROL the intensity of the LEDs, not simply replace them. Actually, I thought he wanted a quick and easy way of regulating the LED using his fan controller. Little did he know that it's neither quick nor easy to do it that way.

Actually, with an additional resistor in-line (since supply voltage is originally 5V according to Tibors, and output of the fan controller should be close to 11.5V at max), it should be fairly easy and straightforward, is it not?

[OmegaZero]

Is there a special physical size of LED that needs to be used to fit in the Antec cases (3mm, 5mm, etc)? Is there a special voltage rating that I need to get?

5mm, Flanged. To be sure you get the right voltage, use a multi-meter on the leads of your current LEDs. Generally I have found this to be 3.5V-5V, so I would guess you will be in that ballpark.

The ones I used from Bivar can be found here. Be sure to add a "-F" to the end of the part number if you order them - without the flanged mounting the LEDs do not stay in place very well.