Fan question

[jason the filter freak]

I'm going to be packing alot of stuff into my nano and pico, yes I'm now building a second.

 

I want to use fans to keep it cool, 3 on my nano/pico getting built from scratch. And one on a 3 gallon eclipse tank I'm going to do some mods to.

 

I was wondering whats the most effective place to mount the fans? I was going to mount them directly over where the water trickles (sump section for the nano/pico, and then where the bio wheel would normally go for the 3 gallon marine land.

 

Anyway i wanted to know if there is any way of getting around having to have a power supply for the fans, can I hack into the balast for DC cuttent to run the fan, or are there fans that run on AC that I can just hack into the main power cord to power, or do i have to find a way to cram in a powersupply? Also being about 2 inches off the water how long can I expect the fans to go before they corrode? or are there small (2x2, 3x3) fans that are water proof

 

(Note the other two are going to be mounted otherwhere on the nano/pico)

 

 

Thanks in advacne,

Jason

[Grav]

Yer scaring me. I'm worried you are going to burn your house down. You need that big black cube looking transformer plug powersupply thing on a small fan like that. Hacking directly into 110 will fry a little fan in a puff of smoke. As for stealing power after the ballast... that sounds crazy too.

 

I'm no expert on the subject, but I don't think anything you are talking about here will fly. Why can't you just plug in the powersupply remote from the hood?

[jason the filter freak]

. Why can't you just plug in the powersupply remote from the hood?

 

I could do that with the 3 gal pico, but I can not for the 5 gal project.

[Rascal]

Jason:

 

A couple of ideas:

 

1) Put the AC/DC transformer inside the hood, then tap into the AC power supply before the ballast to supply power to the transformer, then hook the transformer up to a DC fan of your choice.

 

Most small quiet fans are DC so you will need the transformer. The ones at computer stores are nice because they actually have the specs (db for sound and cfm for amount of air moved) listed on the package. The packaging will also tell you what size transformer to get. You can get the transformer at radio shack but their fans are c**p IMO. You can use a smaller than rated transformer if you don't need as much air movement as the fan is capable of and you want to reduce the noise a little.

 

2) There are some small AC fans that you could use, and then you could just power it by tapping in, again pre-ballast, to the AC power supply. The problem with this is they aren't water proof, and sooner or later salt-creep will get in, especially if you place them inside the hood in close proximity to your overflow. A little silicone (it is non-conductive) in the right places will help, but I would still worry about using an AC fan in this application. There just isn't that much space between current-carrying-exposed-metal and water. You probably know this but for those who don't, there is a HUGE difference between the a 12V DC transformer supplying 1000 mA and the 110 V circuits in your house capable of supplying 15 - 20 Amps. Don't believe me? Strip the ends of the two wires coming after a transformer and then plug it in and touch the bare ends of the wires together. You may get a small spark. You can even hold both of ends in your bare hands and probably won't even feel it. Now try the same thing with a regular power cord plugged directly into an electrical outlet. Crazy? You betcha. That's why using DC powered products near water is so much safer.

 

CAVEAT: I learned about electricity in the Marine Corps, where part of my job description entailed using it to make things blow up.

[dchild]

can I hack into the balast for DC cuttent to run the fan

 

NO!! Leave the ballast alone, lots of power + high voltages in there. Your lamps run on AC anyway so there is no DC to be found inside the ballast.

 

Rascal makes some excellent points, esp. regarding DC vs. AC. Most people don't realize how much power is in 15 amps at 120VAC. I don't really have much to add except make sure your wall wart exceeds the combined wattage requirement of your fans. And when Rascal says "smaller than rated transformer", make sure it is the VOLTS that are lower (results in slower fan speed) and not the AMPS/WATTS, which results in the power supply running way too hot.

 

With a little creativity you can hide the wall wart in a lot of places. I recommend you not hide it in the canopy b/c it will generate heat and take up room you don't have to spare. But if you can't plug it directly into an outlet, can you plug it into an extension cord and hide it behind a desk? How about under a small (but aesthetically pleasing) box on a desk, like one of those decorative Kleenex box covers? Attach it/glue it in place under a tabletop? Superglue should hold it fine, Goop even better i you can find a way to brace it while it dries. Do you have an old laptop power supply? Those usually generate 12VDC with a fair amount of juice, and often have less intrusive form factors. If you can get a wall wart that has a short cord between the "wart" and the "wall", like one that was designed not to block additional outlets in a power strip, you can cut the plug off and splice it in with your power line. Solder and heat shrink tubing will minimize the visual effect of splices. I also recommend you get a multimeter ($8 unit at home depot/walmart/dollar store will do fine) so you can double-check your polarity. I think most fans will just spin backwards if you get the polarity wrong but it could fry them too.

 

Good luck!

[jason the filter freak]

Ok so where can I find ultra small fans, and said power supply (I'm looking for on the 3 gallon fans under 2 x 2 and for the 5 gal 2 fans under 2 x 2 and one fan around 3.5 x 3.5 all estimates are in inches

[dchild]

http://nexfan.com/

http://www.newegg.com/

[jason the filter freak]

http://nexfan.com/

http://www.newegg.com/

 

Ok the nexfan site worked the other didn't but can some one help me pick out the fan thats best for me, it'll be about 1' off the water and have to fit into a 2"x"2 space.