Exaust Fans on New Entertainment Center


  #1  
Old 09-20-06, 02:04 AM
F
Member
Thread Starter
Join Date: Nov 2005
Location: USA
Posts: 11
Received 0 Votes on 0 Posts
Exaust Fans on New Entertainment Center

Hello all,
If given the proper instructions, I know I can do this. So hopefully somewhere there is someone who can design it for me and help me, please do so. Alrighty, I just bought msyelf a really nice solid wood TV stand which has places underneath for my Xbox 360, Pioneer Reciever, DVR box, DVD player, and DVD Recorder. The back is solid wood and the front doors are glass, I am already concerned about ventilation and my components overheating. So I figure I should install about four 119mm vent fans on the back on the stand. I want to wire these fans so that I can control them myself to rev them up and down as necessary, plus power them up and off when I need using the combo speed on/off knob. I know what I want, I know I can build it, but desiging it is another issue. I'm not too keen on where to get parts, voltages and all the other stuff. Here is a link to a sketch of my design idea, keep in mind it's not to scale, the control box should only be about 4-5 inches in width. I plan on using 119mm computer fans, the rest I need some guidance on. I hope someone helps me on this. Thanks all.

http://xs106.xs.to/xs106/06383/idea.png
 
  #2  
Old 09-20-06, 04:35 AM
Pendragon's Avatar
Member
Join Date: Jul 2002
Location: USA
Posts: 1,851
Received 2 Votes on 2 Posts
A single 4" a/c fan would move as much air and be quieter as long as you are choosy.

There's no need for speed control as the fan isn't going to be loud enough nor will you be close enough to hear it, which is the only reason PC's now have temp/speed controlled fans.

If you insist however, www.digikey.com will have everything you need.
 
  #3  
Old 09-20-06, 05:11 PM
T
Member
Join Date: Aug 2006
Posts: 12
Received 0 Votes on 0 Posts
ferris209,

computer fan run on 12 dv ( a transformer), hook the transformer to fan thermostat ( attic exhaust fan stat) and set the temp about 87F
 

Last edited by DIYaddict; 09-20-06 at 07:03 PM. Reason: removed quote as it's unnecessary to quote the entire post
  #4  
Old 10-16-06, 10:00 PM
G
Member
Join Date: Feb 2006
Posts: 94
Received 0 Votes on 0 Posts
Been there, done that!

Been there, done that! Well, not exactly the same, but close enough. I had a client (local coffeeshop) that had a computer in an enclosed area that was EXTREMELY hot. (Not to mention the ice machine that happened to be placed directly across from it, blowing hot air into the enclosure!). Here's what I did and it worked well (I'm planning on doing the exact same thing to my entertainment center):

1.) Buy a 120mm fan that's rated as "silent" (make sure it has a 4-pin molex connector) ... check endpcnoise.com for good ones. I went with a Antec TriCool that has a built-in speed control just in case I needed it (in their situation, sound didn't matter, so I cranked it up).

2.) Buy this 4-pin molex to AC adapter: http://cablesonline.stores.yahoo.net/mo4inpotoacp.html (this is the exact product I purchased and from the same store)

3.) Buy two 120mm fan grills (one to keep cables from getting stuck on the inside and one to keep fingers out on the outside!)

4.) Go to the hardware store with your fan in hand and find some screws that will be just long enough to go through the entertainment center's wood and through the mounting holes of the fan (and will grip the mounting holes without splitting the plastic).

5.) Once you get the above, get out your soldering iron. Your 120mm fan should have a 4-pin molex connector with only two of the 4 places empty. The only problem with the above adapter is that they didn't tie the 5V and 12V grounds together! So, you'll have to cut off the 4-pin molex connector and get another one (old power supplies are great for this). If you look at the diagram on the adapter page above, you'll see one circle that's filled in, while the others are open. You need to "move" the ground on the fan over one position so it lines up with the open circle on the diagram (3rd circle from the left). Solder the red wire coming from the fan to the yellow wire coming from the old molex connector (the leftmost circle in the diagram). Then, solder the black wire from the fan to the black wire on the old molex connector that lines up with the 3rd circle in the diagram (ie: connections on the old molex should be:
1- red wire soldered to yellow wire
2- empty
3- black wire from fan soldered to black wire
4- empty)

you can pull out the unused pins if you'd like (2 and 4 .. that's what i did). To make a nice looking job of it, get some shrinkwrap tubing!

6.) Then, measure where you want the fan to be and use the outtermost ring in one of the grills as a template. Use a drill to make a hole somewhere inside the circle you drew using the grill. Use a jigsaw to cut the rest out.

7.) using the grill as a guide again, mark the holes for your screws. Drill holes just slightly larger than the screws where you marked.

8.) Put one screw through one grill hole and the entertainment center's hole. Using the hole for the fan, hold the fan in place while you screw the first screw in. Do the same for the rest (obviously )

9.) Use the short screws to mount the grill on the inside of the fan.

10.) Plug it in and enjoy not-overheating equipment

here's some pictures of the one I did. Note: this was the first time I ever used a jigsaw, so go easy on me!

http://lloydnet.org/Gallery/Portfolio/Mokas/

You should be able to run two fans off of that one power supply, but you'll have to alter each fan's molex adapter so that it completes a circuit. You have to do this because the AC adapter only provides the 5V ground (which is stupid, because in a computer, the 5V and 12V grounds are common on the molex connector). Just get a Y-adapter (or make your own) and alter it so that the ground is moved over one space.

Sorry if I'm not explaining the wiring well. If you want to go ahead with something like this, e-mail me and I'll draw up a schematic that makes more sense than my words! :P

Like I said, I'm planning on doing this on my system at home. I *think* I'll setup one as exhaust and one as intake so cool air is drawn in and hot air is drawn out evenly. With a good, quality 120mm fan, you will not hear it at viewing distance. I have a high-quality 60mm fan (only because my case wouldn't take anything bigger, unfortunately) in my HTPC (Home Theatre PC) and I simply cannot hear it, the video card fan ("silent" Zalman GPU cooler), the Power Supply Unit (XClio silent PSU) or the CPU fan (Nexxus silent CPU fan) from my couch or anywhere further than about 2 feet on a completely silent night.

Good luck and feel free to ask me if you have any questions
 
  #5  
Old 10-16-06, 10:03 PM
G
Member
Join Date: Feb 2006
Posts: 94
Received 0 Votes on 0 Posts
Originally Posted by Pendragon
There's no need for speed control as the fan isn't going to be loud enough nor will you be close enough to hear it, which is the only reason PC's now have temp/speed controlled fans.
there's also the energy usage consideration ... fans that speed up only when needed will use far less energy than fans that run at a constant, higher speed. granted, it's not like you're running a central air conditioner, but, hey, every little bit counts!

plus, some of us are "blessed" with hyper-sensitive hearing and every little bit of fan noise (including the "whoosh" of air through punched fan grills vs wire fan grills) annoys the heck out of us
 
  #6  
Old 10-17-06, 04:27 AM
Pendragon's Avatar
Member
Join Date: Jul 2002
Location: USA
Posts: 1,851
Received 2 Votes on 2 Posts
The 5v and 12v grounds are isolated in a PC power supply, and are seperated on all PC power supply connectors. That's why there are 4 wires instead of three. The powered device usually has the grounds bonded, but it's not so in the power supply itself.

A 12v fan won't use any appreciable difference in power running at 50% vs 100%, it's so little, it's not even worth mentioning.

An A/C powered fan is almost always quieter than a simular 12v because an a/c fan can have larger blades and run at a lower RPM while still moving the same or more air.

As far as the punched grills, I've ALWAYS cut them out, simply because they don't flow air. Why install a fan and then cover 80% of it's airflow? Never made sense to me, but I guess it's cheaper to punch the case than to install a wire grill.
 
  #7  
Old 10-17-06, 06:46 AM
G
Member
Join Date: Feb 2006
Posts: 94
Received 0 Votes on 0 Posts
Originally Posted by Pendragon
The 5v and 12v grounds are isolated in a PC power supply, and are seperated on all PC power supply connectors. That's why there are 4 wires instead of three. The powered device usually has the grounds bonded, but it's not so in the power supply itself.
i was just going on the info i found when researching that project ... the instructions still work just fine as posted, though


Originally Posted by Pendragon
An A/C powered fan is almost always quieter than a simular 12v because an a/c fan can have larger blades and run at a lower RPM while still moving the same or more air.
well, the ones I've used are rated for "silent" systems (endpcnoise.com) and are designed to maximize CFM while keeping sound low ... the 120mm tricool moves 39 CFM at 1200RPM while only outputting around 25dBa. I have the same fan in my main video editing machine and that's the quietest fan in the system (all fans and PSU in the system are "silent" and are each rated around or below 19dBa). the only sound i get from it is the annoying punched-out grill that I haven't decided what to do about yet. ... because of the poor design of the back of the case, it's not just a simple cutout of the punched grill and replacing with a wire grill (the grill has two "levels" to it, so if i'd use a wire grill replacement, i'd have to use some sort of spacers so the grill was perpendicular to the back of the system)


Originally Posted by Pendragon
As far as the punched grills, I've ALWAYS cut them out, simply because they don't flow air. Why install a fan and then cover 80% of it's airflow? Never made sense to me, but I guess it's cheaper to punch the case than to install a wire grill.
yeah, even a wire mesh would be better than the punch-outs ... the one in my video editing machine is especially poor in design ... just a bunch of 1/8"-1/4" holes punched out ... even worse than the ones most cases have
 
  #8  
Old 01-15-07, 04:52 AM
T
Member
Join Date: Jan 2007
Posts: 1
Received 0 Votes on 0 Posts
Your plan would definitely work, but I personally think it may be a little overkill. As long as you have someplace in the front of the enclosed area that air can get in (a gap between the doors, for example), 1 or 2 120mm fans should be sufficient. As for the speed control, I question its necessity. You absolutely do not want to run the fans at full speed, as the noise would be unbearable.

My suggestion: power 120mm 12V computer case fans with 5 to 7 volts. This will reduce the speed of the fans to the point that they're nearly completely silent while still evacuating enough air to keep it from turning into an oven. Hint: a good, inexpensive way to reduce voltage is to chain several 1N4001 silicon diodes in series with the power supply - they'll drop roughly .75V each. There's no need to purchase ultra-expensive super-quiet fans - almost any case fan will be silent when slowed down enough.

The slower the fan, the quieter its operation. However, the volume of air it moves is directly proportional to its speed, and its pressure it delivers can drop even more. Another consideration: stalling at startup. Nearly all case fans will start without a problem at 7V, some as low as 3V. IMO, the best thing to do is to start with a 9V power supply and experiment with the number of diodes until the fan is quiet enough, still blows a decent amount of air, and starts reliably when turning power on and off.

As for switching power, my solution was to drive the power supply from the switched outlet on my receiver. Since I use my receiver for everything entertainment-center-related, the fans will always be on when they need to be without messing around with switches. The only reason you would ever need speed control is if the amount of air being moved was not sufficient to maintain a decent temperature in the enclosure. IF you have a decent intake area on the front, that shouldn't ever be an issue.

I've seen plans for many elaborate DIY units with ductwork, fans outside the unit, etc. While impressive, it's really not needed. You don't really need to keep it freezing in there - just keep some fresh air coming in and you'll be fine. Your equipment is designed to dissipate heat, you just have to get it away from the unit. With this approach of computer case fans (easily under $10 each), a 9V DC power supply (you probably have one laying around), and 1N4001 diodes to drop the voltage (under $1 each), you can have an effective, very inexpensive cooling solution without a lot of hassle.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: