Re: searching for a wide alpha cpu heatsink (2nd request)

[Alan Young <ayoung teleport com>]

Alexander Huemer wrote:
> hi tony,
>
> i have a 3 wires too.
> re-wiring a pc fan is not possible to my knowledge, because the signal 
> is completely different.
> a pc wants to have pulses (as you said) so that they can measure the 
> rotating speed of the fan.
> the original fan of my alpha (some strange panaflo) gives a certain 
> voltage on one wire if the fan is turning. when you stop the fan, the 
> voltage goes up and the alpha stops. when you remove the fan, the 
> voltage is missing and the alpha does not run either.
>
> my "alpha fan simulator" does just provide the required voltage, that's 
> all.
>
> building a heatsink from scratch is of course possible, but that's not 
> the way i want to go, if i find somebody who has a BIG BIG heatsink for me.

You can rewire a PC fan to be used in a Alpha as long as it's a fan that 
provides the sense line.  All you need to do is pop the wires out of the
3 pin connector and rearrange them in the right order and pop them back 
in.  If you have a newer CPU FAN with the small 4 PIN connector that 
provides the PWM line, that might work too, just leave pin 4 (PWM) 
unconnected.

On a PC CPU fan, the pin order is

1 GND
2 +12V
3 Sense

On the Alpha CPU fan, the order is

1 +12V
2 Sense
3 GND

A couple of other things to look at is a FAN funnel adapter that can 
allow you to mount a larger fan on a smaller heatsink and standard
PC sound quieting materials and components.

Alan