I'm working on a Dell XPS BTX to ATX conversion. Dell has a control board for each of the case LEDs. That is 3 separate boards. Each control board has one power wire and a - wire for each of the RGB LEDs. I bought a 4 port fan switch. It has it's own power cable that plugs into the power supply. Each switch has it's own wires with a + and - pin. So what I'm trying to figure out is how to run to the LED control boards. My dumb ass didn't check the specs properly. I thought I was getting a 0v to 12v switch. But it's a 6v to 12v switch. Instead of plugging into a 12v source I tried plugging into a 5v and 3.3v on the P14 connector from the power supply. I'm trying to figure out if this is even possible. I only need one of the switches power leads to power the board. Adjusting the switch gets me from red to orange to white. So obviously I'm not controling each color individually. I'm thinking I either need to take apart the switch, and rewire it, or just go get some true toggle switches and do this.
This is the switch I have. https://www.walmart.com/ip/HDE-3-5-...0498&wl11=online&wl12=715911845&wl13=&veh=sem
There is a guy that has done this before me with toggles, but I'm having a bit following what he did.
"The problem is to join the 5 wire connectors with the 3 switches and power. I found a 10 pin male (Maplin), stripped the wire and joined each pair, giving 5 wires. This I labelled. The GRND pair is not used. The 3 x LED (black) wires go off to the 3 switches, and the POWER wire (red) I wrapped around the black ones. But at the switch end I looped the red wire back, together with another black wire (that joins all the switches) to produce a two wire power cable. This could be plugged and connected to any power source but my choice was to screw them into the ex-P14 connector block by the PSU, with the live going to the +3.3v orange wire. I believe using 5v is normal but 12v could cause burnout."
Here is a photo of his wiring. http://i1289.photobucket.com/albums/b511/John_Tauwhare/0JT031_zpsd77ede37.jpg
Here is the toggles I'm thinking about getting if I can't make the dimmer switches work. https://www.amazon.com/yueton-Rocke...&qid=1499782112&sr=8-9&keywords=toggle+switch
They look like they should pop right into the switch box. I think by following this I can handle the toggles. http://www.learningaboutelectronics.com/Articles/Common-anode-RGB-LED-circuit.php
I just want to take one more crack at the dimmer switches before I call it a day.

 

My read on these cases mentions that they work and run fine on 3.3 volts. That said I am not sure where you are going with the fan speed controller? The fan speed controller is a basic unit which uses four pots to vary the dc voltage to a fan. Were you looking to change LED brightness or intensity by varying the LED voltage? Generally this is done using PWM (Pulse Width Modulation) rather than varying the LED voltage. The latter will work but is not a very good way to go about it. If you want to take this route I would not connect the fan speed controller to 12 VDC as it is designed. I would feed it 5 VDC and use the fan lines out to drive the LEDs. If you know how you can move the pin on the molex connector from 12V to 5V. Where you mention Dell had an output board for each LED I am not sure what they were controlling? Was it LED brightness?
Unfortunately your PhotoBucket links do not work. PhotoBucket just times out.
The button switches you linked to are just simple On/Off switches, what was the plan for them?

Ron

 

Dell used settings in the BIOS to control the on/off state of each LED to give you the color combinations. Here is an example of the one for a XPS 730 (not exactly mine but they are all pretty close in the 700 series.), http://www.ebay.ca/itm/Genuine-OEM-...451494?hash=item2c890648e6:g:kTwAAOSwd4tT4myB
I thought I might control intensity, but at least I thought I could control the on off state of each LED. Might have been easier if I had read the specs and actually got dimmers that went to 0 and not a low of 6v. In basic form I would be happy just being able to control each LEDs state so I can do color combinations. The toggles is where I was going to go if I could not get the dimmers to behave as I want. I was going to remove the dimmers and replace them with the toggles. I kind of need the 3.5 bay box so I have a place to put it. The toggles look the same size and I measured the dimmers and they measure the same size as the specs on the toggles. Pop out the dimmers, put in the toggles and wire it up. Like I said I have some miner control with the dimmers. I can do Red with the dimmer all the way down, as I turn it up I get a yellowish orange and then white. I'm not getting just blue, or green, or say a purple which would be red and blue. The main reason to keep the dell control boards is simply they fit the case and already installed. Rather then get fancy and try to remove them and undo them. They come with 5 wires. Red = Power, Blue = Blue LED -, Green = Green LED -, White = Red LED -, Brown = no one knows who has come before me. They all just ignore that wire.

 

I was thinking the dimmer switch was blocking 6v, but it makes more sense to me now it's halving the load. So even though I put it on a 5v and also tried a 3.3v, I'm never going to hit 0v with the dimmer, I will hit 2.5v and 1.65v respectively. As long as I have even that small amount of voltage going to the Anode I'm not sure I can control the color states? So now I'm thinking I'm going to have to get the toggles to truly control on/off states to make the color combinations. Really wishing I paid better attention and got one of the dimmers that does go to 0v. I'm assuming Dell has resisters in the boards as when I'm at minimum on the dimmer I'm only seeing the Red LED. The intensity changes as I go up and then it goes to the yellowish/orange as I pass the resistors for blue and green letting them come on, and finally at full on the dimmer I'm getting white which means all 3 RGB LEDS are on.

 

OK, I have an idea of what you are looking for. A RGB (Red Green Blue) LED typically has 4 wires, one wire for each LED and either a Common Anode or Common Cathode which is common to all the LEDs. Each LED normally has a resistor in series with it and in some cases the series resistances are built in. Turning each LED on full brightness would yield:

Red = Red
Green = Green
Blue = Blue
Red + Green = Yellow
Red + Blue = Purple
Green + Blue = Aqua
Red + Green + Blue = White

So what is usually done is a RGB LED is in a single package containing actually three LEDs. In addition to the above examples using different colors full on each color can be "faded" in or out making for some interesting combinations. Aside from a Dell Case (chassis) RGB LEDs are commonly sold in strips similar to this. Strips are ready for 12 volt use with the resistors built in making for easy use.

Back to the Dell BIOS. Looking at the board link you posted the BIOS likely ran some code to control the LEDs. Actually pretty easily done. Been years since I bought a Dell and even then they were only laptops. My old Dell Laptop must be 8 years old.

Here is what you can try. Keeping it simple I would start with low voltage, like the available 3.3 or 5.0 volts and try using the dimmer or if you prefer an ON/OFF switch. Really depends on the effects you want. While LEDs work much better with PWM you can use simple ON/OFF and get some effects. The above ON schemes for RGB should yield the colors I posted. I would start with low voltage as a LED will die in a heartbeat with over voltage and once they cook that's it.

Today, if I were dressing up a case I would likely just buy a strip like I linked to and use a small micro-controller to drive it making for nice case illumination effects.

I was thinking the dimmer switch was blocking 6v, but it makes more sense to me now it's halving the load. So even though I put it on a 5v and also tried a 3.3v, I'm never going to hit 0v with the dimmer, I will hit 2.5v and 1.65v respectively.

Oh Yeah, the reason is they were designed for simple fan speed control. Running off 12 volts they don't want the voltage to get so low the fan quite or won't start. As I recall units like that using a pot with 12 volts applied will output about 7 to 12 volts so your numbers make sense.

Ron

 

I did use 3.3v and 5v. What I did was run each colors ground to separate switches ground, and it didn't matter if I ran one or all 3 power outputs to the Dell mini boards power. I got the same results. Red with all 3 switches at minimum. The any combination of increase in power would give the yellowish color and finally white. I read in the article above "When the toggle switch is flipped to the +3V end, both ends are at +3V and there is no electrical difference. Therefore, no current can flow, and the LED is off.". Would it be possible to hook the + side of the switch with the ground so I have a cancelling voltage. Would that allow me to basically switch off an LED by stopping the flow of current? I have 4 dimmer switches on it the unit. Or I could even put 3.3v on the Dell mini boards, and plug the dimmer box into 5v.

 

Yes, anytime both ends of a LED are at the same potential it will be off. Here is what a RGB LED typically looks like:


The above should be close to a typical RGB LED. I omitted any series resistors so only the LEDs are shown. The color mixing is what I posted earlier so you can mix for a color variety.

Ron

 

That didn't work. When I put power on the ground of the LED the box started to get that cooking smell. I think I might be better off buying the toggle switches and replacing the dimmer switches. Then I can achieve a proper on/off state with each switch. There are already resisters built into the Dell mini boards. So it should be as simple as tying switches and mini boards power together and then running each LED ground to the - on the switch.

 

Then just add switches which will give you the color combinations we mentioned earlier. Long as you get the effect you want. There is no way to PWM drive the LEDs so On or Off for each color seems logical.

When I put power on the ground of the LED the box started to get that cooking smell.

Not sure why you would apply power to ground? The image I posted was merely to show how a RGB LED can have either a common anode or a common cathode.

Ron

 

I picked up the toggle switches noted and it works. Only thing is I cannot get the little LED on each toggle to work. There are 3 posts on the toggle. A copper bronze that is suppose to control the on switch LED. Two steel ones for the basic toggle. I can put a common ground and one of the RGB grounds on the steel pins and it controls the RGB LED perfectly. But the only way I get the LED on the toggle to work is to remove the common ground, leaving the RGB ground. As the box has a slot for 4 switches and I get 4 colors in the pack I ran the first toggle (Yellow) for the Anode power. So 3.3v coming in to steel post and 3.3v going out via other steel post to the RGB common Anode power. Have a ground on the copper post and that LED works. At this point the circuit functions to control the RGB LEDs, so I'm not sure I'm going to bother with the switches own LED. I've tried different combinations and the RGB LED and the switch LED do not work at the same time. It's one or the other.