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 Post subject: Fan controller problem...
PostPosted: Mon Oct 04, 2004 11:44 am 
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Ok, instead of going out and buying a fan controller to mount in a bay, I decided i don't want them in a bay. So I bought my own switches and dug up some old LEDs. I hooked it up so the LED acts as a power indicator (blah blah blah you're all modders, you know what i mean), and it works fine, but the LED draws power away from the fan. Is there any way I could make it so that the fan draws power away from the LED and runs at full speed? Should I just move the LED to a different part of the line? Or is there anything I can do? I just want the LEDs to turn on with the fan without taking away fan speed or brightnes from the fans blue LEDs (its an LED fan)

Any suggestions?


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 Post subject: Re: Fan controller problem...
PostPosted: Mon Oct 04, 2004 12:11 pm 
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WhiteRabbit22 wrote:
Ok, instead of going out and buying a fan controller to mount in a bay, I decided i don't want them in a bay. So I bought my own switches and dug up some old LEDs. I hooked it up so the LED acts as a power indicator (blah blah blah you're all modders, you know what i mean), and it works fine, but the LED draws power away from the fan. Is there any way I could make it so that the fan draws power away from the LED and runs at full speed? Should I just move the LED to a different part of the line? Or is there anything I can do? I just want the LEDs to turn on with the fan without taking away fan speed or brightnes from the fans blue LEDs (its an LED fan)

Any suggestions?


Hmmm...Never thought about it.

Questions:

By switches you mean "toggle" on/off? Not a pot.,reostat, dimmer etc...?

You have the led located on the proper side of the curcuit (I think that second inline after the fan)?

The LED is the right voltage?

Can you get a lower current LED in the right voltage?

I haven't played with this stuff in a long time I must admit. Been in school. But, I always thought the Fan would take whatever it needed from the PSU rail to operate. What size is your PSU? It sounds like its taxing the PSU to me - not the fan.

Wait for another answer.

But the info would help

Manta


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 Post subject:
PostPosted: Mon Oct 04, 2004 3:28 pm 
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i believe manta is right. the fan sucks as much power as it needs. a delta hi-rev fan doesnt suck as much power(or air) as a cheapo speeze fan. i dont think a litle led is taxing your PSU to death so i'd just try switiching it to the other side of the circut and if it still seems to slow you down double check your connections and make sure you have a very solid connection where you soder


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 Post subject:
PostPosted: Mon Oct 04, 2004 7:16 pm 
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btw, do those on/off and dimming switches have a special name, so I could ask for them at radio shack or something?

Fans need molex connnectors which have 4 wires, how does the switch work with that? As you can see, Im a little new at this. :lol: Thanks in advance for any replies. :D


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PostPosted: Tue Oct 05, 2004 6:37 am 
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Universal wrote:
btw, do those on/off and dimming switches have a special name, so I could ask for them at radio shack or something?

Fans need molex connnectors which have 4 wires, how does the switch work with that? As you can see, Im a little new at this. :lol: Thanks in advance for any replies. :D


go to ACE hardware or something and ask for a toggle switch.

they are antec fans, they have two wires goin to a molex + one neutral. I've got the switch on one wire, and the led on the other... maybe i should try putting them both on the same wire...
I've got a 250 and a 175 external (modded) goin in through the back, 425 total. I think I'm gonna mout the 175 somewhere inside if I have room. after all, its an eMachine T1150 case. This thing is killing me...


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 Post subject:
PostPosted: Tue Oct 05, 2004 8:10 am 
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WhiteRabbit22 wrote:
Universal wrote:
btw, do those on/off and dimming switches have a special name, so I could ask for them at radio shack or something?

Fans need molex connnectors which have 4 wires, how does the switch work with that? As you can see, Im a little new at this. :lol: Thanks in advance for any replies. :D


go to ACE hardware or something and ask for a toggle switch.

they are antec fans, they have two wires goin to a molex + one neutral. I've got the switch on one wire, and the led on the other... maybe i should try putting them both on the same wire...
I've got a 250 and a 175 external (modded) goin in through the back, 425 total. I think I'm gonna mout the 175 somewhere inside if I have room. after all, its an eMachine T1150 case. This thing is killing me...



I don't think it will matter, but switch sides with the LED and try it on the 250PSU. How do you know its sucking juice? Are you measuring the RPM? How? MBM?

Anyways - I would really look at what type of LED you are using. You might want to buy one that you know the specs on and match it to the right curcuit. I don't think an LED can act as a resistor - but you never know. (Gives me something to try too). Oh yeah - LEDs are one way DC IIRC. IF you hook it up backward it won't light and I think it will limit the curcuit. So thats not your problem is it?

Keep us posted.

Manta


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 Post subject:
PostPosted: Tue Oct 05, 2004 8:12 am 
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Universal wrote:
btw, do those on/off and dimming switches have a special name, so I could ask for them at radio shack or something?

Fans need molex connnectors which have 4 wires, how does the switch work with that? As you can see, Im a little new at this. :lol: Thanks in advance for any replies. :D


Toggle is on off only. I would just look at the different switches at RS.

The plug may have 4 wires, but the fan only has two or three.

Manta


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 Post subject:
PostPosted: Tue Oct 05, 2004 11:51 am 
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I can see the LED of the fan get dimmer, and the fan slow down. I'm just testing them on my test PSU, it's the 175, maybe I should put them on the 250, or just puke up some money and buy a better PSU.

I'll try switching the LED and the toggle and see if that makes a difference when I get off of work at 9.


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 Post subject:
PostPosted: Tue Oct 05, 2004 1:41 pm 
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Hell, I lost a post? Damn getting old here.

Your LED circuit should be in parallel with your fan. Here is a drawing of what things should look like. Also the drawing reflects a series resistor with the LED. This is not required if you are using a store bought 12 Volt rated LED as the series resistor will be built in (encapsulated).

Image

I omitted the polarity, but the + (positive) would be on the top and notice the LED Cathode side is - (negative). The LED circuit is in parrallel with the fan motor, and the switch is in series with both.

A typical basic off the shelf LED has a foward working voltage of about 1.2 Volts and a foward current of about 10 to 20 milliamps (literally next to nothing). This is why a resistor is incorporated in series with the LED. The resistor limits the LED current and drops the excess voltage.


Last edited by Reloadron on Tue Oct 05, 2004 2:29 pm, edited 1 time in total.

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 Post subject:
PostPosted: Tue Oct 05, 2004 2:27 pm 
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Reloadron wrote:
Hell, I lost a post? Damn getting old here.

Your LED circuit should be in parallel with your fan. Here is a drawing of what things should look like. Also the drawing reflects a series resistor with the LED. This is not required if you are using a store bought 12 Volt rated LED as the series resistor will be built in (encapsulated).

Image


Thanx Ron,

I have a couple question since you seem to know your stuff.

Is it because of the resistor? I didn't realize they had one built in.

You are saying the resistor built into the LED will change the circuit if you hook it in series but not if you hook it in parallel - I can see that.

You wanna give a quick tutorial on multi color LEDs?

I mean, how are the different colors controlled?

That would be kewl.

Manta


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 Post subject:
PostPosted: Tue Oct 05, 2004 3:04 pm 
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Hey Manta, how goes it. I actually just edited my post with a tad more info. Generally in the case of basic cheap LED (Light Emmiting Diodes) the plastic case influences the color. Also, on better grade LED's color is dependent on the material used in the actual PN junction of the diode itself.

Then you will sometimes see what is called a tri-colored LED. These are actually two PN junctions reversed. Just meaning the Cathode of one is common to the Anode of the junction beside it (all in the same tiny case). Now the polarity determines the color seen. If we reverse the polarity the LED will glow Red or maybe Green, another reversal and it will glow the opposite of what it was. The third color is Yellow. Now, if we were to apply a small AC rather than DC current, the thing would appear to glow Yellow only because the Red and Green are switching so fast, our eye percieves Yellow.

These are popular in threshold detector circuits. We could build a Window Comparator for example. Here we would use a few devices called op amps (Operational Amplifiers) whose outputs would swing + or - depending on an input voltage. Lets say we want to monitor a 12 Volt supply. If the supply voltage dips below maybe 11.8 volts the LED would turn from Green to Red or likewise if the voltage exceeded maybe 12.2 volts, the same would occur. Thus our Green window would be between 11.8 and 12.2 volts. Yellow in that case would never show.

As to the resistor, think that was part of the edit I did. However, the purpose of the resistor is to limit the current flowing through the LED. Like I mentioned, a typical LED working voltage is about 1.2 volts, and the normal foward current is about 10 to 20 milliamps (ten to twenty thousanths of a single amp). Lets say we have a 1.2 volt 20 milliamp LED we want to power off 12 volts. Well if we were to directly apply 12 volts to our little LED it would be toast real quick!

Now we calculate our series R. This is done with good old Ohms Law. R=E/I or Resistance is equal to the Voltage divided by the current. Thus we now have 12 Volts, minus the foward voltage drop of the LED 1.2 of Volts or 12 - 1.2 = 10.8 Volts. OK 10.8 / .020 (20 milliamps) = 540 thus we would place a 540 (give or take a few) Ohm resistor in series with our LED.

Now if we stroll to Radio Shack and buy a 5 Volt or 12 Volt LED, we are actually buying a LED with the resistor built in. You may not see it, but rest assuerd it is in the encapsulated case.

The circuit I just winged together is basically what the poster should have.

Ron


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 Post subject:
PostPosted: Tue Oct 05, 2004 4:03 pm 
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you sure do know your stuff, i just learned more in those 10 minutes then i did from 8-3 in school today


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 Post subject:
PostPosted: Tue Oct 05, 2004 5:52 pm 
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gramaton cleric wrote:
you sure do know your stuff, i just learned more in those 10 minutes then i did from 8-3 in school today


Ditto


Thanx Ron :)


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 Post subject:
PostPosted: Wed Oct 06, 2004 1:11 am 
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Thank you for the compliments. However, it is what I do for a living. I just hope the little drawing lends a bit of help to the original poster.

Ron


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 Post subject:
PostPosted: Wed Oct 06, 2004 6:05 am 
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this is how my setup is laid out. I think the problem is the placement of the LED.

[ Molex ]--/[SW1]---[3PinA]---[12vFan]

[Connector]----[LED]---

(note:the molex connector is 1 connector, not 2, and the LED goes to the 3 Pin, I just couldn't get the post to get it right)

sorry for the rough typed diagram, I dont have anyone to host images for me right now. Should I ditch the 3 Pin connector? Or can I still keep the 3 Pin, and just reposition my Switch/LED? I'm only asking because it looks a little different than the previous diagram because of the Molex and the 3 Pin... Thank you for your help.


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 Post subject:
PostPosted: Wed Oct 06, 2004 4:43 pm 
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Hmmm, if you did it like this:

[ Molex ]--/[SW1]---[3PinA]---[12vFan]

[Connector]----[LED]---

You would seem to have things in a straight Series loop sort of. Working off a standard PSU Molex connector, the connector should have four pins. A typical Molex connector, like the ones that power the drives, has four pins.

Pin Wire Colour Signal
1 Yellow +12v
2 Black Gnd
3 Black Gnd
4 Red +5v

You would only care about pin 1 (+12 Volts) and pin 2 (common). Then things would be configured like the drawing I posted. Either way, the idea is that you are placing 12 Volts accross the fan and LED configuration. Also, unless the LED you are using is rated for 12 volts and is just a LED you had lying around, you may need a simple series resistor inline with the LED like my drawing. Much like my post to Manta, anywhere around a 500 to 600 Ohm basic carbon resistor rated at maybe 1/2 watt. Also observe the correct polarity.

If the LED is again just a plain old LED and has no polarity markings, the plastic housing should have a small "Flat" where one of the leads exits the case. The side with the flat is the Cathode or Negative side. Remember the LED will go accross the fan leads and not in series with the fan leads. The switch then is placed in series with the fan and LED parallel combination.

Also, the fan should have only two wires coming from it, likely a red and a black (+ and - respectively). Should the fan have 3 wires, the third wire is a speed pickup and would not be used. Some fans include that fan speed signal output.

Things should look like the small schematic I posted in order to work correctly. If the drawing I made is hard to follow, just let me know and we will see if we can't simplify it a little.

Ron


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