After finally getting everything else done on my case, I started to wonder what I was going to mod next. This post inspired me:
Hard Drive Cooler

It looks like he didn't mod the wires at all, which I plan on as well as adding a switch. So, how should I wire it (and why if possible)

Ok, I have a question on this topic. Say I have 2 120mm fans, that run on 7 volts. If I spliced the two fans together (i.e. 2 fans and 1 molex) would they effectivly draw 14 volts, or what? (probably a real dumb question, but I am clueless when it comes to electricity)

Thanks

Casper

They'll draw what you give 'em as far as voltage is concerned, the only thing that really changes is the current.

If you wire them with the two red wires together at the molex and the two black wires together at the ground lead on the molex, that's in PARALLEL, and that means they'll have the same input voltage, in this case, if they're hooked up to a 7 volt supply, they'll each draw whatever current they want at 7 volts. Let's say 1 amp each, for a total of 2 amps.

If you hooked the red of Fan1 to the positive at the molex, the black to the red lead of Fan2, and the black of Fan2 to the ground in the molex, then they'll be in series. That means you can follow a path from the voltage source thru both fans and then to ground.

This is called SERIES, and if the two fans are identical, they'll each get exactly half of the voltage you applied at the molex. So in this case 3.5 volts each, and they'll also draw half the current. Meaning that in this wiring scenario, they'll only draw 1/2 amp total, because the current must flow thru both fans to get to ground (doubling the effective resistance)

This is a bit much to take in all at once, if ya have any more questions make a new thread and ask, plenty of pimps can help ya with this one, we just need to get out of Gumby's thread... LOL

EDIT: Gumby, put 'em in parallel unless you want to undervolt them to 4 volts each, they might not even turn at that low a voltage. Plus, if they're in series and one dies and goes open circuit, they other two will stop... And we don't want that, no we dont...

EDIT THE SECOND: Maybe Gumby wants this in the thread, in which case ignore me, it's not hard, other peeps manage it...

Gumby - Wire them in Parallel, that what I did and I havent had any issues, just cleaner case wiring
All my fans are on full 12v wired to a small speaker wire terminal.
like this...

Clean wiring is one of the best rig aspect's to have In my opinion..

Thanks Sport - That's exactly what I was looking for. I knew there was something that wiring is series did, but for the life of me, I couldn't remember.

ok, somebosy explain how to wire fans in parallel, Im a splitter n00b i guess.. Somebody asplain deees!

The 12V rail splits in two. One fan on each of the split rails. The ground leads reconnect on the other side.

edit:



The yellow is 12V rail. The black is ground.

Here's a picture for you:

so parallel is better? you gotta solder em or just twist n wire-nut em?

I solder everything.

I plan on soldering. I am also having a kill switch on it as well. Will post pics when done (hopefully)

I know nothing about electronics but in wiring speaker if you run parallel you get double the flow and series gets half the flow. So is wiring the fans different. I just wanna be sure because it seems like it might be easy to overload the circuit by running parallel (with a line that already has say 2 cdroms on it). I really don't know that is why I am asking, just to be sure.

with speakers you are driveing a load with an amplifier and it is reallt different in alot of ways compared to a fan.
simple electrical theroys. when you run in parallel the voltage draw will stay the same but the amperage draw will go up. when you run in series the voltage draw is increased because of the loads being one after another therefore it will drop and blah blah blah and amperage draw will stay the same.

Carbon, not quite right, there is no such thing as voltage draw, the load will only take the voltage you feed it. If you have two loads in series, they share the voltage. They draw current accordingly, if they have 6 ohms resistance each (making a total of 12), and they have to share 12 volts there is a resultant 1 amp current draw.

I(current in Amps) = E(Volts) / R(resistance in Ohms)

(Why we refer to volts as E in equations is beyond me, but put in my vote to change it to V to be in line with the rest of the world...)

It is easy to exceed the current load running things in parallel, but the average 80mm fan only runs about 1-2 watts (maybe a lil more, but my point is made), about 0.08 to 0.16 amps each. I believe you're running 40mm fans, and their draw will be miniscule campared to the 80mm buggers. You can find the wattage of your fans on the label somewhere (and maybe even the amperage)...

I(current in Amps) = P(power in Watts) / E(Volts)

Conversely,

P(power in Watts) = I(current in Amps) x E(Volts)

I think there have been threads in the forums about power consumption of devices like HDD's and CDROM's, but I just got home from work so research is outta the question right now, you go lookie LOL

Bottom line, your three fans will draw bugger all power, go hook 'em up and take pics so we can see how they look

Take it easy...

Psychofunk,
Remember that in speaker wiring you're dealing with impedence, which is different than resistance (although not much different). It does work out the same way when wiring resistors though. If you wire two 50 Ohm resistors in series, you effectively get one 100 Ohm resistor. If you wire the same 2x50 Ohms in parallel, you effectively get one 25 Ohm resistor. The thing to remember when parallel wiring resistors is that you must deal with the reciprocal of the resistance value (which I'm not good at, so that's all I can remember! hehe)

Sportbilly,
'E' is short for Electromotive Force, which is what Hehr Ohm called it instead of Voltage. 'I' is short for Inductance, which means pretty much the same as Amperage.

@_@

attached is a little diagram to hopefully help out. Brings back memories of Physics in HS.