The second fan is spinning in the wake of the first fan, spacer or not. You can't pull in twice the air or create twice the pressure this way. It's been tried. There is a marginal improvement but nothing to write home about. We even tried affixing the blade assemblies directly to each other to keep them in sync. Balancing was a pain in the arse. We even tried filling the gap between the blades and the outer casing wall. That helped but was a lot of effort. We put a nose cone to a model rocket over the motor and a home made venturi over the case, that was fun, but not a huge help. Been there, done that. Have fun experimenting, but don't set your expectations too high is all.

I'd think that to have further meaningful pressure there, you'd need the fans to spin in different orientations. Ever tried counterrotating fans? (even though they'd have a painful amount of resonance noise)

Properly designed centrifugal blower fans are supposed to be capable of MASSIVE pressure output compared to normal casefans.

We were unable to try counterrotating fans because we never found reverse pitched fans. Thought about it though. Turbos generate great pressure, no doubt.

Here is a website that has several temperature controllers to choose from.
http://www.acortech.com/.sc/ms/cat/1110039...ture%20Monitors

Here is a fan that has built in temp control.
http://www.xpcgear.com/smartcasefan2.html

I ordered the Kingwin TC-02S from newegg. One more item out of the way for my pj.

Hey gents,

So if I were to seperate the glass and the first fresnal by a couple inches (to protect the frez), would i cut the cooling slot between the frez and lcd? or between the glass and frez? or both? If i cut the slot between the frez and the lcd, how will the air evacuate the space between the glass and frez if there isn't a cooling slot in the lid between the two. Is is even necessary to separate the glass and frez? or will it be ok to have the frez flat up against the glass?

As always thanks for the help!!

As Brainchild told me directly, with proper cooling it is definitely OK to put the fresnel against the glass.

Greetings. Anyone know where to get a 120v 120mm fan at all i can find are 120mm are 12v dc.

a good source (as any other) is www.nexfan.com

scratch that, i think they only do PC stuff, maybe www.meci.com, or pricewatch.com

Ebay. They have tons of stuff for cheap.

If you have a Sayal Electronics place nearby, they carry all sorts.

I bought my 120mm 120VAC fans at Princess Auto. They weren't really cheap, but they cost less than the local computer shop wanted for 12V units. IIRC, they were $14.99 CAD each. These are nice units, worth the money, IMO.

allelectronics.com has a variety of fans, dc and ac. I've ordered from them in the past and have had no problems.

http://gallery.bcentral.com/GID5092728DD37...Fans/120mm.aspx

Are either sleeve bearing or bal bearing styles generally quieter than the other?

nice read at http://www.silentpcreview.com/files/ball_v...eve_bearing.pdf

conclusion seems to be that ball bearing lasts longer, but sleeves are a bit quieter... of course, its all relative.

one thing to note, is that ball bearing fans tend to make more noise when they start dieing(sp?), while sleeves tend to just slow down and eventually quit. this might sound ideal, but in a situation where we're not seeing the fan, and knowing how crucial they are to these designs, i'd rather have the indication noise to let me know its about to go (like car breaks).

of course you can always introduce circuitry/components to tell you when the fans aren't working properly, but then that all depends on how much extra junk you want to put into your design. every little 'extra' is a potential extra problem.

Holy crap, i cant for the life of me find the ebay link to the thermostat posted earlier from the beginning of this thread. Ive searched and browsed through threads but no luck. Can anyone help me out? Thanks.

Just go to Lowe's if there's one near you. They have a temperature-controlled switch for $11.99.

Quick question for anyone out there.

I found a thermoswitch rated at 120 deg F. Will this work and wheres the best place to place it...near the reflector?

Thanks

I couldn't give an opinion on the whether the theromswitch will work but I do know that the temp you should be concerned with it the temp right near the LCD - that's the part that needs to stay <105F. I remember a post someone had showing the temp at the lamp was almost 600F!

Found This. Thought it might come in handy and for the price ($3.50), it's worth a try.
Its a fan alarm, if one of your fan stops an alarm goes off letting you know.




Heres the link:
http://www.geeks.com/details.asp?invtid=FA-100&cat=FAN

Features/Specifications
General Features:
Supports four (4) cooling fans for HDD, CPU, case
exhaust, etc.
Two (2) 3-pin fan headers
Two (2) 4-pin power connectors
LED indicators tell you which fan is malfunctioning
Built-in speaker
Alarm reset switch
Package Includes:
Just Cooler FA-100 Fan Alarm System
NOTE:
This fan alarm looks for open circuit breaks with the
fan and DOES NOT monitor..
-- fan RPM speed

I personally woudn't bother, if anything the Radio Shack temp sensor has an temp alarm and I may even consider a thermal fuse. But I don't really plan on leaving my projector unattended.

I might try this on my projector. I looked it up and found this page with some math theory that supports fan stacking in high static pressure environments.
Fan Math

We definately have more static pressure (with the long narrow slot and passageway between the LCD and tempered glass) than a computer case.

Found an interesting part i hadn't seen before. It's a small powersupply that has a UPS function built-in. Seems like it would work to keep fans running even if power was cut off. It needs to be hooked to a sealed lead acid battery for the UPS function to work, of course it also has AC in to recieve power from your socket.
http://www.allelectronics.com/cgi-bin/cate...5046&type=store

3.3vdc
5vdc @ 6.5amps<-- good for running fans at low rpm
12vdc .8amps <-- full rpm
UPS function <-- connects to a sealed lead acid battery (not included)
Click to view attachment

My projector is well below 95 degrees on the projection lens side of the lcd with all the electronics, but about 120 degrees on the lamp side of the lcd, is this acceptable?

Most people are using 105F as a maximum temperature for the LCD, so if you are at 120F right near the LCD, then I would say you might have a problem. You may want to take a look at your cooling setup and fan choice ??

Has anyone tried or considered closing off the light section (bulb to tempered glass) all together, ie. not leaving the gap at the bottom for airflow, thus containing the bulk of the heat and have 1 or 2 input and output fans in this section only to circulate the hot air?

I have done this. I used a piece of thing gauge aluminum with a hole cut in it to expose the arc of the bulb. I covered the opening with a piece of tempered glass and used one fan in the bulb area. The LCD still got too hot with this setup. I then added a quiet, low CFM fan, in the area between the heat shield and LCD sled using an additional opening in the side of the box and not drawing air between the LCD and fresnel. This still had the LCD getting too hot. I then uncovered the air intake to draw air between the LCD and fresnel (as is the standard design) and covered over the air intake that I had just added. This cooled the LCD very well.

I subsiquently removed the tempered glass (the piece I had was too thick and really killing brightness) and covered over the air intake I had put in the bulb area... so basically i'm back to the standard design with an additional fan between the heat shield and LCD sled. This keeps my temperatures below 90F measured at the gap near the bottom of the LCD. I do plan to add a piece of 1/8" tempered glass back to the heat shield as I feel this does make for the most effective cooling.

Check out my PLOG for more info and pics... I will post more updated pics today.

-gs

Would there be any reason why we could not use a second tempered glass say 60-70mm from the first one? Would this effect the light distrubution.

The idea is to keep fans away from the LCD and use 4x120mm fans running on 5v (quiet) two at the rear and 2 underneath with dust filters blowing air into the box. Then we could seal up from the tempered glass nearest the fresnel all the way back to create a enclosed dust free section.




sry about the crap diag


comments?

For anyone interested, an already "Stacked Fan" that was used by Dell Computer was available at American Science & Surplus for $3.95 Each.

Fans Page If this link does not take you there go to http://www.sciplus.com click on Motors, Blowers & Pumps then subcategory Blowers.

If you already have such a unit, try hooking up your big arse shop-vac(running in a distant room through a long extension hose)to pull air through your existing fan-port.......my 5HP shop-vac is sucking air through the port so fast, I can actually hear the air moving out of the light chamber!!!



Heat?! WHAT HEAT???? FLOL!


And if you are worried about overheating your hose, just put the lil' bugger on "blow" instead, but be sure to clear the hose of all dust first!

on the subject of air vents... are light leaks really a problem when u have air intake openings say above the fresnel / lcd gap?? i mean, if light is going up there, its light thats not hitting the lcd anyway right?? or is the bigger concern stray light coming in and washing out the light from the fresnel?

I wouldn't be concerned about stray light getting in, so much as focused light getting out; try beveling the slot so that the light gets bounced back onto the fres, not out of the box. Just a thought.


Then again, if your box is "blacked-out", or if the light source is tightly collimated onto the fres/LCD, then light escaping OUT won't be an issue, altho I would place a "blacked out" louver of some kind over the slot to ensure ambient light doesn't leak IN.

Ive just installed 2 92x92 fans in the back of my PJ, im not running any tempered glass, (since ive used a old overhead as base). I am considering if I should?

I did a quick test with the lamp today, and after about 5-6 minutes the heatshield (right behind the lamp reflector was at 60c . And the space between the first fresnel and the lamp was at 38c.



Should I install more fans? Should I consider a glass between the fresnel and the lamp?

(Or can I run without it? The original overhead didnt have any.)

Ive tried to read my way trough, to find some magic number to work with, but im kinda unsure of what temperatures you guys qualify as "max"?

I am considering buying 3 of this fan:

Primecooler 92x92.

Hey,
I really like the thermostat design. I am going for size (7' lcd) on my project and was wondering how large/small are some of the temperature control devices.

Thanks,
Joe

Joe - I just bought the attic fan version from HomeDepot. It must be nearly 4x3x1". Not too big for my box and only 15$.

Anyone interested in sharing their latest PJ experience with regard to cooling, fan types, noise, etc.?

I am using 2 - PCAC evercool bay fans and while they are keeping my temp @ 95 F they are really loud. I think the 23 dB at 100 CFM published rating is false. Especially when you factor in the increase in noise from resistance and the resonating of the PJ's wood enclosure. I have been able to turn the speed down slightly and still maintain the same temp. This helped a little, but they are still rather annoying during the more quiet parts of the movies. I don't hear them during the "machine gun fights".

Is anyone using multiple muffin fans with lower CFM that are getting the job done and keeping things quiet? I was thinking about 3 to 4 80mm or 90mm fans that would have a combined CFM of 100 or more. Seems like these size fans in the 30 to 50 CFM range have pretty low noise ratings.

Thanks,
GateMan

If you are in the USA try SVC.com the panflow are the best and the cooler master are panflow copys. both use rilfe bearings that are a lot quieter than ball bearings. It is geting hard to find any that don't have LED lights on them but the LED's can be removed easy. the 25000 rpm are a little loud and the 21000 are hard to hear. Use 4 the 21000 rpm that should be good. the 21000rpm don't make quite the pressure so go for some xtera CFM. I have been making computers for ten years and love the panflows. The cooler masters are so close that I think they ar made by panflow. good luck

I know Brain is pretty adamant on the cooling slot on top and air gap under the temp glass/ Lexan. I just have to ask what is the harm in completely sealing off the light chamber with a full height sheet of glass and blowing air straight across the LCD. I am not concerned with either light leeks or fan noise because I am going to locate the projector behind the wall and project through and access hole (ala movie theater style).

If you completely seal off the light chamber, without a fan creating air flow through it, the wood would eventualy catch fire! Your wire insulation would probably melt, possibly causing a short, and poof there goes your whole house. See, no air flow. You lose your house. With it you also lose the front half of the projector which has the lcd which you've taken great care to keep cool against the blazing inferno burning behind it.

Thats just what I think.

Perhaps I should have mentioned sealing the light chamber from the front half, NOT from the whole universe . I intend on blowing air through the light side separately. LOTS of fans.

Had an interesting conundrum regarding my wiring. I plan to use 2 Evercool PCAC's for the system's cooling, and I found a 5A 12V AC/DC PSU, for laptops. I was trying to figure out how to wiring everything to one switch and have a temp controlled cooling circuit stay alive after shutoff. Every wiring diagram I found ar saw, used a DPST switch but was designed with 2 seperate power supplies for the 12V components, 1 for the LCD, and the other for the fan(s). I didn't have a lot of space to play around with. So I thought the single 12V supply would do. Long story short, the DPST switch was not going to work. Either I would not be able to isolate the LCD from the fan(s) or I would not be able to maintain power to the fan(s) without also powering the LCD. I came up with 2 solutions:

1) Get a seperate thermostat that would kill the power to the LCD, I couldn't figure the right temp that would let me do that right, or

2) use a 3PST (3 Pole Single Throw) switch and wire the thermostat and fans to the third pole, thereby isolating the fans from the LCD.

The only con I see is that there will be live power in the box after the switch is thrown to off, however I think that is the way all the wiring diagrams with a temp controlled fan circuit are setup.

Here's my diagram:

Hi this is my first post, so i thought i would offer a idea as to how to help cool the box.

Simply put this is a old pot growers tech to cool the grow lights.

first get a pyrex tube off e-bay (cheap)

http://cgi.ebay.com/PYREX-BAKE-A-ROUND-BRE...1QQcmdZViewItem

Then install the light inside it, and draw the air through it via a side mounted fan.

let me know what you guys think...


Freedom

You have a wire mixed up in your diagaram....
In that drawing you have the eballast getting power all the time, and the AC/DC power supply running through the switch.
You turn that switch off, the fans will stop and the bulb will stay on....
I think you meant to have the AC/DC power supply hot all the time, and run the power to the eballest through the switch. Just switch the top 2 black wires on the left terminal strip

#1: Hmm . . . first post and already marking yourself as a toker?

#2: It would interfere with pretty much any reflector.

#3: AMAZING what you can get on ebay - ain't it!?!?

#4: Welcome to LumenLab!

Good call on the wiring. That's what I meant. And what you said is the way I'm setting it up. It's slow going. But I'm making headway.

Steamer

Hello,
I was just at my Local homedepot (in Ontartio Canada) and no one there could tell me where I could find one of these thermostats ( i guess in canada we have no need for them) in any case I was wondering if any other fellow canadians knows where i can find one locally or maybe I could arrange with Xanderphillips to send me one? Also Brain, this would be a great item to add to your store... an all in one shopping experience!

hopefully i get a answer starting my build as we speak but can't find this Thermostat to control the fans!

thanks
Igu

Igu,

You can go to Allied Electronics (I think it's alliedelectronics.com) and order the snap disc thermo switch. It is item # 928-9983. It it closes (operates the load) at a certain temp (anywhere from 93deg F to 107deg F)and doesn't open (kill power to the load) until it get's under 65 degrees F. it's only $4 U.S. and they will ship it to you.

Steamer

Igu, I'm in Canada too, Wpg. I had Pm'd Brain about it, he has went to HD in the US for me and sent me one and just put the bill thru LL. I tried to look here as well but HD US does NOT = HD CDN so there parts are different.

I'm sure if you PM him nicely he'll do it, he's a good guy.

Brain or others, I took a look at the wik guide and was wondering why this design is better then the reverse.
Another words, why is the 3/8 intake slot not below the projector(if sitting on say 2 inch legs) pulling cool air up along the lcd and straight across the top and towards the top back of the projector. I say this because since heat rises you would get stronger air flow with the same fan power.