Computer fan

[evon610]

I have my PC fans powered off an old PC supply - plenty of power available and cheap to boot! Just connect the sense wirte to ground to get the supply to power up (check wiring on google depending on your supply type)

[watto]

look on the side of the PSU, it will have the colour codes of the wires so you know which one to connect the fan to, if its a PSU from a newer computer you will have to hotwire the on/off switch, just look on the side of it, it'll tell you which are the on/off wires. the PSU also has a fan inside it, so you can use that as an extraction fan aswell if ya want, just put half of it inside the growbox and the other half outside. An easier way is to just use a nokia phone charger like I do. the middle wire of the fan is just a temp sensor wire, dont worry about it.

 

watto

[Al B. Fuct]

Arrgh, I've actually got a few 12V AC adaptors, but I just realised I need 12v DC.

I was so close to setting that up right now...

 

Go to Jaycar or Dick Smith and buy a 1N34 diode ($1 on a bad day, otta be closer to 25c) and wire it in series with the fan. The diode will convert the 12V AC to (rough) DC, good enough for a fan motor. If the fan motor spins the wrong way or not at all, reverse the diode or swap the wires going to the fan.

[Al B. Fuct]

This is the way I plan on trying to do mine. Tho I only have a 30v adapter, so I'm going to have to get some resistors and do some handiwork...

 

~M.

 

If you have a 30VDC power pak and a pair of 12V fans, try running it with the fans wired in series. They'll spin fast as each fan will be getting 15V, but they ought to do OK.

[Al B. Fuct]

I have setup a few pc fans to run off a 12v DC power adaptor.

 

One thing i have found is if u run any more than one fan off them the fan drops in speed quite a bit, so u need something that can put out enough power to run more than one.

 

I have a 16v DC power adaptor that i run 2 12cm pc fans off, one fan runs great but the second i hook up the other one u can hear the speed of the fans drop a bit but not as bad an a 12v adaptor dose...

 

Are you connecting these in series or parallel?

 

If you have a 12V supply and 12V fans, they should be paralleled, not connected in series. If you series them, each fan is only getting 6V.

[Al B. Fuct]

the middle wire of the fan is just a temp sensor wire

 

While the point is pedantic, the yellow lead is not a temp sensor wire- it's for rotation sensing. When the fan spins, you will see a rapidly winking 12V signal on the yellow lead, winking off once for each revolution of the fan. The PC counts the winks to tell if a fan has failed and has stopped spinning.

 

You'd probably only see the winks with an oscilloscope- an ordinary voltmeter will not respond quickly enough for you to see the very brief winks.

 

As you said, just snip off the yellow lead- it's not needed in this application.

[Al B. Fuct]

For those of you who don't know the difference between series and parallel, here's a little visual aid:

SERIES:

 

 

The voltage applied to each of 2 fans when wired in series will be 1/2 the supply voltage. If there's 3 in series, the voltage applied to each will be 1/3 of the supply voltage. This is handy when you have a 24V supply and two fans or a 36V supply & 3 fans.

 

PARALLEL:

 

 

The voltage applied to each fan connected in parallel will be equal to the supply voltage.

 

You can add more fans in parallel, up to the current supply rating of the power supply.

 

Most power pak transformers can source about 300mA, enough to run 4-5 computer fans. If you exceed the current sourcing capacity of the power pak, the supply voltage will drop as you add more fans. Overloading the power pak will cause it to overheat and prematurely fail.

[eexpee]

Most people say smoking weed makes you stupid, but I think Al B. Fuct is a sure example that it doesn't...

 

Fuck, it's so bad my dad is dead against my weed habit. Otherwise I'd ask him to help me set up my box/es

He knows all of this stuff due to his career...

haha, and I wish i'd paid more attention when he offered the advice in the past

 

But thanx for you're useful information guys, and Al B. Fuct.

Though, I think i've established i'm going to need a bigger box considering the pots will take up most of it...heh...

[Al B. Fuct]

Most people say smoking weed makes you stupid, but I think Al B. Fuct is a sure example that it doesn't...

 

heh, I'm still stoopid enough to grow dope during prohibition. It's a four-legged bitch if you get busted.

[yota]

heh, I'm still stoopid enough to grow dope during prohibition. It's a four-legged bitch if you get busted.

 

prohibition? that what they call probation in Aussy?