Fan yellow wire info...

MeltMan · 11-24-2001, 08:29 PM

Does anyone know exact specs on the yellow fan wire? Does it convert straight Hz signal into rpm's? or is there some math converion involved? I guess maybe that is the "fan type" in motherboard monitor. The reason I ask is that im adding an LCD to my computer and it is electroluminescent backlit. I made an inverter, and it happens to be adjustable frequency. Essentially it changes the color of the EL screen from a blue green, to a sharp blue, and i wanted motherboard monitor to display the Hz that the LCD was operating at. The EL pad runs off of a fan header and i might as well use the yellow wire if it is feasable. Plus add OOOhhh and AAAhhh factor in there... Anyways, what voltage does that pin take? I did find out that the fans put out a squarewave signal- like my EL driver. Thanks techie guys

Butcher · 11-24-2001, 09:52 PM

It varies from fan to fan but usually they put out two pulses per revolution, square shaped as you say. This signal is trasmitted directly down the fan sensor wire, any rpm conversion is done by the motherboard.

MeltMan · 11-25-2001, 09:27 AM

Correct me if im wrong, but the signal is negative correct? They must put out an incredibly fast switching rate because my multimeter cant even detect it as ac volts...

Butcher · 11-25-2001, 10:04 AM

I'm not sure if the pulses are negative going or not, checking on a scope would be easiest, sadly I don't have one.
It doesn't really matter which are detected though - you still get the same number.

futRtrubL · 11-28-2001, 04:27 PM

A multimeter on ac wouldn't be able to sence the voltage, a 5000RPM fan would be putting out 10kHz. Also if it's a pulse output then it has a very short duty cycle.

Edward

UnaClocker · 11-30-2001, 12:16 PM

It uses a hall effect pickup in a fan, just like the ignition in alot of 80's cars.

11-24-2001, 08:29 PM	#1
MeltMan Cooling Savant Join Date: Aug 2001 Location: KS Posts: 374	Fan yellow wire info... Does anyone know exact specs on the yellow fan wire? Does it convert straight Hz signal into rpm's? or is there some math converion involved? I guess maybe that is the "fan type" in motherboard monitor. The reason I ask is that im adding an LCD to my computer and it is electroluminescent backlit. I made an inverter, and it happens to be adjustable frequency. Essentially it changes the color of the EL screen from a blue green, to a sharp blue, and i wanted motherboard monitor to display the Hz that the LCD was operating at. The EL pad runs off of a fan header and i might as well use the yellow wire if it is feasable. Plus add OOOhhh and AAAhhh factor in there... Anyways, what voltage does that pin take? I did find out that the fans put out a squarewave signal- like my EL driver. Thanks techie guys __________________ MeltMan Lurker Supreme!

11-24-2001, 09:52 PM	#2
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	It varies from fan to fan but usually they put out two pulses per revolution, square shaped as you say. This signal is trasmitted directly down the fan sensor wire, any rpm conversion is done by the motherboard. __________________ Once upon a time, in a land far far away...

11-25-2001, 09:27 AM	#3
MeltMan Cooling Savant Join Date: Aug 2001 Location: KS Posts: 374	Correct me if im wrong, but the signal is negative correct? They must put out an incredibly fast switching rate because my multimeter cant even detect it as ac volts... __________________ MeltMan Lurker Supreme!

11-25-2001, 10:04 AM	#4
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	I'm not sure if the pulses are negative going or not, checking on a scope would be easiest, sadly I don't have one. It doesn't really matter which are detected though - you still get the same number. __________________ Once upon a time, in a land far far away...

11-30-2001, 12:16 PM	#6
UnaClocker Cooling Savant Join Date: Apr 2000 Location: Bremerton, WA Posts: 514	It uses a hall effect pickup in a fan, just like the ignition in alot of 80's cars. __________________ The UnaClocker Watercooler Extraordinaire! Overclock till it goes BOOM!

11-28-2001, 04:27 PM	#5
futRtrubL Cooling Savant Join Date: Jul 2001 Location: Kingston, Jamaica Posts: 204	A multimeter on ac wouldn't be able to sence the voltage, a 5000RPM fan would be putting out 10kHz. Also if it's a pulse output then it has a very short duty cycle. Edward

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