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Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 1:58 pm
by 1024MAK
1024MAK wrote: Mon Nov 13, 2017 1:30 pm As for your existing fan, if you have some rubber O rings of a suitable size, you could use these. That is what is used on some computer fan mounting kits.
But note that O rings are normally used between the fan and the bolts/screws that are used to fit the fan to the enclosure/case or heatsink...

Mark

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 2:08 pm
by 1024MAK
Lardo Boffin wrote: Mon Nov 13, 2017 1:24 pm For the electronically minded - if we reduce the voltage to the fan will it just reduce the speed a little?
I am wondering whether there will be a good tradeoff between speed (and noise) and cooling ability?
Short answer, normally yes. Either use a suitable resistor or use a lower supply voltage.
Long answer, not always, due to the "motor" being a brushless type. Inside, there is an electronic circuit, which switches each coil on and off in a sequence, this causes a permanent magnet to try to follow the magnetic field generated by each coil. So the resistor cannot be too high a value/the supply voltage cannot be too low, otherwise the magnetic field strength from the coils will be too low to attract the permanent magnet...

Mark

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 2:23 pm
by Paul
I think about something like this :

https://www.reichelt.de/Luefterzubehoer ... ARCH=%252A

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 2:45 pm
by Lardo Boffin
I have some silicone washers which are the right size just no bolts narrow enough. :evil: The smallest I have is m3.5 but I need m3.
A gasket type approach would be good but I can’t find any that are anywhere near small enough.
Does anyone know of any good brand of cooling fans? That are this small.. The one I have is 25 by 25 by 10mm. I think 7.5mm would be better given the clearance and additional height taken up by the vibration damping.

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 2:58 pm
by Moggy
Rather than faff around with resistors or making the job more complicated than it needs to be just use a 12v fan tapped off 9v.

I have done this on a Fuller cased zeddy result adequate air movement and near silent running, the fan doesn't need to running at 10,000 rpm to shift enough air.

Cheap/small fans by nature are badly balanced and this is exaggerated when run at full speed as I've said before a gentle throughput is all that's required not a hurricane.

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 3:21 pm
by Lardo Boffin
Moggy wrote: Mon Nov 13, 2017 2:58 pm Rather than faff around with resistors or making the job more complicated than it needs to be just use a 12v fan tapped off 9v.

I have done this on a Fuller cased zeddy result adequate air movement and near silent running, the fan doesn't need to running at 10,000 rpm to shift enough air.

Cheap/small fans by nature are badly balanced and this is exaggerated when run at full speed as I've said before a gentle throughput is all that's required not a hurricane.
Thanks. Do you know any good quality 12v fans that are ideally 25 by 25 by 7.5 or failing that 25 by 25 by 10? I guess we could go to 40 by 40 by 10 with a little surgery...

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 3:30 pm
by Moggy
Lardo Boffin wrote: Mon Nov 13, 2017 3:21 pm
Moggy wrote: Mon Nov 13, 2017 2:58 pm Rather than faff around with resistors or making the job more complicated than it needs to be just use a 12v fan tapped off 9v.

I have done this on a Fuller cased zeddy result adequate air movement and near silent running, the fan doesn't need to running at 10,000 rpm to shift enough air.

Cheap/small fans by nature are badly balanced and this is exaggerated when run at full speed as I've said before a gentle throughput is all that's required not a hurricane.
Thanks. Do you know any good quality 12v fans that are ideally 25 by 25 by 7.5 or failing that 25 by 25 by 10? I guess we could go to 40 by 40 by 10 with a little surgery...
Just nipped into attic and removed a chipset fan of the same dimensions as yours,Lardo, and quickly wired it up to the 9v on my test 81 with xpand and zonx box connected and at 9v running I was surprised to find it still a tad noisy but at 5v really quiet and still a good airflow so will continue this evening to fit to a normal zeddy and post results.

As for suppliers I will continue searching this afternoon (forget Farnell silly money) then report back.

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 3:45 pm
by Lardo Boffin
Thanks Moggy. I’m on limited time to find these things at the mo!

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 4:02 pm
by Lardo Boffin
I forgot to say earlier that after 3 hours of running The Gauntlet I opened up the case and quickly did the highly technical finger temperature test.
I believe that just too hot to touch is around 60 degrees C and it was only pleasantly warm to the touch so still nice and cool.

Re: ZX81 cooling fan

Posted: Mon Nov 13, 2017 4:04 pm
by Andy Rea
No no no your all wrong... you gotta go big :D

https://youtu.be/EM2G5vLGcQQ

:mrgreen: :mrgreen: