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Question about LEDs in case

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January 23, 2013 4:00:09 PM

Hey guys n gals, quick question

I have a cheap case, an apex PC-389-C
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The front has two little LEDs on each side that basically display vertical bars. One on the right for power, and assuming the left is for hard drive usage which flickers, and looks kind of annoying. Any way to make the left LED run constant like the right LED? So there will be two full blue bars.

Thanks

More about : question leds case

a b ) Power supply
January 23, 2013 4:20:49 PM

Hello... you can take the wires from 1 LED and wire them to the wires of the other LED... cut-strip-wirenuts/solder/twist and tape... LEDs have polarity to them... match polarity.
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a b ) Power supply
January 23, 2013 4:21:23 PM

I think you can't do that, the Hard drive activity LED it's supposed to do that, so if it's really that annoying you can unplug it from the motherboard or power a blue LED somehow via Molex (I don't know how to do that, so I can't help you)
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January 23, 2013 4:30:22 PM

Well, I guess you are not concerned with the warranty on a $25 dollar case! You also don’t seem to care for a visual indicator for your hard disk activity, OK.

Ironsounds has a good idea, but I wouldn’t use wire nuts. Realize that the LED’s will most likely dim in parallel, as the load would double.

If you really want to mod the case a good place to go to would be Radio Shack. You should be able to replace the LED in the front panel assembly with another one and power it through a molex or sata connector.

Another possibility is to replace the pin sleeves on your current LED with a molex. You can look up wiring diagrams online.
Molex connector: GND, +12v, +5v, GND
Sata Connector: 3x3.3v, 3xGND, 3x5v, 3xGND, 3x12v.

Be sure to use a LED that has a rating to withstand the power you connect to it.
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a b ) Power supply
January 23, 2013 5:08:10 PM

Hello... a resistor is required to limit current to an LED ( and is already installed on the motherboard )... typical current and voltage is 20ma and 2 volts... since the resistor is on the motherboard, the original LED will be dimmer with the two LEDs wired in parallel, ( as only half the current will be avaiable to each LED ), but I offer a quick fast solution/option for you, with minimal cost and effort... and if you don't like the results... change it back.
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January 23, 2013 6:17:33 PM

Ironsounds, blue LEDs have a higher forward voltage than 2.0V, usually about 3.1V, and little ones merely soldered to a wire should run at significantly less than 20mA to retain good lifespan.

The important question is how does the power LED look. If it is too bright then soldering the HDD LED in parallel is a possible solution with them both dimming some, but occasionally you might find that two in parallel without separate current limiting resistors can result in one being a little brighter than the other based on random variance in the forward voltage of different specimens of LED even when the same batch, color, etc.

Instead I'll give what to me would be the more ideal solution. Buy a molex Y-adapter cable, for example this one, but you can probably find them on eBay too for around $1 delivered slowly from Hong Kong:
http://www.svc.com/4pinpowsupmo.html

Do not use the motherboard headers for power at all, unplug both and desolder the wire, then on each branch of the molex adapter, on the 12V led going to the LED's anode, solder in a series resistor such that you have two resistors, each going to its respective LED. Doing the math and shooting for 10mA per LED, you'd have (12.0V - 3.1V) = 8.9V drop, so at 10mA that's a 890 ohm resistor.

That's not a very common value of resistor so you might substitute 1 x 1K ohm per LED, or solder two 470 ohm (1/4W will be fine, even 1/8W would) in series per each LED.

The other option is to use a multimeter to measure the existing drive current for the power LED then decide from there whether to adjust the current higher, lower, or keep it the same to affect the brightness. Once you decide on a drive current there are online calculators for LED resistor values as an aide. Try to keep the drive current below 15mA for best lifespan, and for the most subtle illumination I might shoot for under 5mA per LED, especially if you will be using the system in a dark environment.
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