[RESOLVED] How to make an artifical fan

[BladeRunner]

Probably quite simple if you know electronics, but I don't, although I could put together a device if I had a circuit & component diagram to work with. I want to make a circuit that will give an artificial "pulse" to mimic a fans rotation, preferably adjustable. Any ideas or sites links welcome.
The reason is I will be water-cooling the GPU on my GF (part of a zero fan sys build), and want to be able to use the Asus Smart Doc monitoring software without it popping up telling me the fan has died all the time.

 

[shaun3210]

I had that problem when I fitted a borb to my Leadtek GeForce2 GTS. At the time the best driver for the card was the Leadtek one that included a monitor. Very annoying. I solved it by sticking the standard fan to the bottom of my modem with blutack

. Cant help you with the electronics bit though. Sorry

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1GHz AXIA T/Bird @ 1480MHz.
FOP-38.
Abit KT7A RAID.
Crucial 256MB CAS2 PC133.
Leadtek GeForce2 GTS 32MB @ 235/410.
Blue-Orb.
Creative Soundblaster Live 1024.
IBM Deskstar 75GXP 30.7Gb

 

[Bartleby]

I don't use the Asus software (I use MBM), but can't you just tell it not to monitor the fans and not do anything in the event of a fan failure?

If you wanted to actually get some kind of feedback, I would figure out a way to extract an electronic pulse from the waterflow, so you can use the "fan" monitor as a water-flow monitor. This leaves you with two options, as I see it

The first way, and more desireable would be to create a monitor for the water flow. You would need to either get another output from the motor in the pump, or use an extra turbine attached in the pipe to obtain a turning motion. With this, you could attach a similar device to what is inside the HS fan - an electrical contact that opens and closes once per rotation. Just sent 12v through this and into the monitor on the fan header.


The other way would be to get an electrical oscillator (or build one) that operates at about 100 Hz (6000rpm) and connect that to the monitor on the fan header. Radioshack should have some kind of LED oscillator you can buy.

I hope you can make something of this

 

[BladeRunner]

WARNING!! YOUR HEAD WILL EXPLODE IN 5..4..3

You lost me at "oscillator"

I had looked into flow monitoring and manufactured items are not cheap. Unfortunately you can't dissable the fan monitoring, (unless you could hack the program).

I'm not to bothered about monitoring it to much anyway as it has temp and overheat protection in the software. All I need is to give it a pulse. I don't really know exactly how it does this, (I know the pricipal) but which part does it pulse back the + or - and how many pulses per rev etc, (it isn't necessarly going to be 1 per rev).

Problem is it wont stay minimised in the task bar with no fan rotation information. It gets excited about wanting you to replace the fan, (which is actually impossible because I could never get a reply from asus as to how or where you could get a replacement fan anyway of the type they use, has a tiny non standard VGA board connector).

Like I say I could make something but I don't know how. I think it would need to pulse the supply from the actual graphics card fan header to work.

Someone must know a way to do this please.

 

[Bartleby]

On second thought, the most simple way to solve this would be to hook up your old fan in the case to provide the required feedback.

If you fed it 7v, or maybe even 5v (if it spins

), it would generate very little noise. Without a HS attached, and subsequently little turbulence, a regular fan should be quiet.

Or hook up an exhaust fan on the back of the case to the cpu fan header. This would work also.


If you wanted to build a circuit, I could make a simple schematic for an electronic part that would be very cheap to put together. The end result would be cheap (~$10), be very low power, and produce no noise. This would be the ideal solution if you are not concerned with water flow monitoring.

LMK

 

[BladeRunner]

Bartleby

Thanks M8, and If you could give me a circuit design to build that would be great. Not too worried on the cost factor as such. The flow monitoring devices I found were for accurate monitoring, as such costed big. (£150 +)

I could do the fan thing like you say but I trying to build a Zero fan system, and some smart ass will always point out this fan if I call it such

The fan runs at 12V and it is a three pin header although Like I said smaller than any I've seen before.

[This message has been edited by BladeRunner (edited 06-20-2001).]

 

[Oliy]

Bladerunner, what do you plan to do about the PSU? Are you gonna watercool that?! That would be wikid but make sure you don't get any leaks or anything in there, it's high voltage stuff Make sure you have a good fuse in the plug!

 

[BladeRunner]

Bartleby

I found this info:-

MOLEX (three-pin motherboard) connector

The Molex connector has three wires: + (usually 12V, usually red), GND (usually black), and SIGNAL (usually yellow or white, but there are no clear standards). Unless you are a board designer, only the + and GND wires are of interest to you. (For the curious: The SIGNAL switches between NC and GND twice per rotation, resulting in a square periodical signal if you connect a (low) voltage.

Ok so there is nothing to say Asus have it the same on the v8200's fan header, but it would follow that it most likely is.

Oliy

Yeah I'm very careful as far a leaks go. I test my water-blocks by putting 2 Bar (28 Psi) air pressure in them and then immersing them in water for a week or so. If they wont leak any air at 2 Bar then the definitely wont leak water at near atmospheric.

I also really don't want to kill my PSU (an Enermax 530 Watt). It is totally over the top for my system but the advantage is that running my sys is a walk in the park for it and the air that comes out of it is never anything but cool.

 

[JollyRoger]

would a simple astable not do the trick? I only have GCSE electronics so I'm not sure, but I think you could rig up a very cheap Astable circuit to provide you with on-off oscilations, I used one to provide a clock pulse in my GCSE project, but I can't remember how to do it (3 years ago!!!).

 

[JollyRoger]

Blade is this that machine you were talking about on TekHeads with the underground water tank? I think thats sooo coool man, I love that design.

 

[Gomez Addams]

Look into circuits using the 555 timer IC. It can be configured in all sorts of ways and should be able to do what you need. It is also very inexpensive

Unfortunately, I don't have my linear circuit design books any more or I could help with this. Sorry :|


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Friends don't let friends buy P4s.

 

[CALV]

Oh so its working again

Bladerunner I mailed you but may as well post here to incase anyone else is intrested, as Gomez posted, I think the 555 is the way to go, heres a pic for ya:

the 555 costs 29p so wont break the bank!

Also you may want to look at this project from Maplins, its only a fiver, its a metronome but maybe you can replace the speaker with a fan but I dont know weather it will pulse fast enough without modification

[This message has been edited by CALV (edited 06-20-2001).]

 

[Leoslocks]

I thought that Asus PC Probe has the option of disabling fan monitoring. Perhaps this is a newer version than what you are using.

 

[BladeRunner]

Firstly let me say thanks for all the input so far, and you'll need to keep it coming> I can soldier stuff and have a basic understanding of what componments do, but beyond that I'm lost.

Leoslocks

It's actually the Asus Smart Doctor app that comes supplied with their Geforce cards. The card has an extra hardware monitoring IC that monitors GPU & Ram temp (GF3), AGP power level, and has "Rain" style cooling for the GPU and fan rotation monitoring. Very nice to have.

Unfortunately you can't disable the fan rotation monitoring so if the fan is unplugged the program wont stay minimised in the task bar.

I'd imagine this circuit would need to use the 12v supply from the card's fan header to work, and send a pulse back to the rotation pin, that would give at least 2000 rpm indication at a guess. I going to need a good walk through on the circuit

 

[cyril1]

I agree the 555 timer is the way to go. Do you have a scope at your disposal to check and see what the signal looks like?

It sounds like the fan is supplying pulses between 12V and ground. If you have a scope or a voltmeter to confirm this then it would be a simple matter of modifying the 555 to produce the frequency of pulses that you need.

 

[Bartleby]

I think all your "rpm replicator" will need to output is a quasi-digital signal; something with a regular square wave. The 555 timer would be fine, and here is an alternative method.

I am reminded of my highschool electronics project in which I built an LED oscillator.

I found this schematic here
copy the ascii text to a fixed-width editor for the schematic. I could scan a better copy, but you would have to wait a while

All you need are:
- 2 NPN transistors (2n3904 or 2n2222 will do fine)
- 4 10kohm resistors
- 2 ~3uF capacitors
- One solder board from radioshack
- some wire

-----+--------+--------+--------+------> +12V
| | | |
R1 R2 R3 R4
| | | |
| + | | + +------> SIGNAL
+---C1---+ +---C2---+
c| | | |
\ | | |c
Q1 |------|--------+ b /
/ b +---------------| Q2
e| \
| |e
+--------------------------+------> GND

(note the polarity on the capacitors if you use electrolytic capacitors - the round cylinder ones)

Connect the circuit as shown, using the V+ and GND from the fan header

The operating frequency is dependent on the values of R2/R3 and C1/C3, approximately by the following formula:
f=3/(RC) - assuming R2/3 and C1/2 are respectively the same values.
Using the values above, you get 100Hz, or 6000rpm. You most likely won't find 3uF capacitors, so use the nearest standard values - 3.3uF or 2.2uF.

Hope this helps!

 

[CALV]

Balderunner do you think you could make the circuit in the above pic that I posted? if so, I'll work out some approximate values for you for the other components, But I need to know what frequency you need (i.e. RPM that the "imitation fan" needs to run at), the circuit can easily be built on veroboard if you are familiar with putting stuff like this together, Idealy you would need a scope to measure the frequency, but you could replace Ra or Rb in the pic with a potentiometer which would give you some flexibility, does your mobo have a spare fan header that allows speed monitoring, if so, you could build the circuit and plug it into the spare header and use MBM5 or similar to check the speed before you attatched it to your vid card.

 

[cyril1]

For 6000rpm the freq would work out to 100hz but I would want to verify what the fan signal looks like before I built a circuit.

I suspect it is a square wave between gnd and 12V. Very easy to make this with the 555.

 

[Gasman]

Wow!
This is a lot of tech talk.

I think you should change the topic heading:

" Who can make me one of these? "

The only time I ever got to play with a CRO was at school.

Oh yeah, the reason for my post, my Asus Smart Doctor has two temp gauges. Doesnt yours? Check your new GF3 CD.

 

[cyril1]

After re-reading your post Blade I believe there may be no voltage supplied by the Fan signal wire. The NC would stand for No Connection in other words open circuit. That means the fan either supplys an open circuit or a ground depending on where it is in the rotation.
The actual voltage is probably supplied by a pull-up resistor on the board. If that is the case then the circuit design must be one that that supplies grounds or opens at a 100hz rate.
If you have a voltmeter measure that signal pin to ground with the fan disconnected to see if there is a voltage on it.
You would not want to supply 12V to the circuit if there is already 5V there. The current has to sink somewhere.