There both like a foot long
336mm and the other is like 11".

I've done research but there isn't any fan out there thats small as evercool that claims to push 100cfm.

Thats why I was asking if that thing really pushed that much air in a earler post .

How is the evercool wired? I bought a transformer to change 120v to 12v, but there are two wires on one side and three on the other. I assume the side with two wires is the 120v in. The other side has two yellow and one black.

The evercool has two yellow and one black. obviously the blacks will be connected, but how do i determine which yellow goes to which. Or does it simply not matter.

Thanks in advance for any help.... don't want to ruin the fan so i haven't tried anything yet. Would really prefer to hear from those who have used the evercool.

Hold on there. If it is actually a transformer, you still need to convert to DC. Are you sure you have DC out? What exactly did you get?

One other thing i would like to add. I noticed somewhere that people were talking about the evercool being loud and that enlarging the air inlet on top of the box would help. If you are going to do this wouldn't it also require an increase in the opening below the tempered glass. If the inlet is 3/8ths then the space below the tempered glass should be atleast that.

I don't know if Bernoulli's principle(not sure of the spelling) comes into play here if you don't change the gap at the tempered glass. But if you didn't change the gap it would cause this:

At the inlet air pressure would be high and speed low. At the opening below the tempered glass the airspeed would be high and the pressure low. in the light chamber we would go right back to high air pressure at a low speed. This would occur all over again at the fan. At the fan air pressure would be high and speed low. Inside the fan speed increases, pressure drops and(if the fan can't get enough air) The fan get bogged down trying to suck air through which causes an increase in the fan noise..

If I am wrong and, I REALLY DOUBT IT(being that I taught this stuff for a number of years), Let me know.

By the way I tired and this could all be the ramblings of a fool

Actually there is alot more to it than that but that is the jist.

Oh i didn't think of that Deathray... It is a 120vac input center tapped secondary transformer.
What it actually says is 12.6-volt AC, 450mA power transformer.

I just looked at the fan and saw that is DC. How much does a convertor cost?

the transformer comes from radio shack and has a catalogue number of 273-1365a

Well could just by a wall wart type of adapter. I prefer the kind with a cord on it rather than the type with prongs on the box. Heck you probably have one lying around the house that would work. You could also use a PC power supply or even an open frame type power supply. Just need 12VDC out with an amperage rating bigger than your fan(s). Take that thing back to Radio Shack. You could put a bridge rectifier on it to get DC, but I doubt that it's worth it. (Don't ask me how to do that)

I'm using this one from a guy on ebay. It's for an external SCSI box, I thought that it was kind of cool, but it has no fan so it would need to be in the cooling circuit. I haven't tested it yet.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...5740824750&rd=1

Ok... I looked around the house and found a transformer that converts 120v to 12vdc at 1000mA. would this work? and the are still only 2 wires.

the fan has actual ratings of 12v DC and current rated at 0.07A ~ 0.13A

It looks like it would work. the fan .07A ~ .13A and the transformer at 1000mA(milliamps) seems to be in range.

That should work. The fan uses only about 300mA I believe. Check the power supply, there should be symbol that looks something like this: -c- This will show whether it is center positive(usually they are) If you mark the wires on both sides before you cut off the plug you should be able to determine which wire goes to the center with a meter. Then you will know which wire goes to the + on the fan. On the other 120VAC end(if it is polarized) the fat spade is the neutral and the narrow spade is the hot. If they are the same, it dosen't matter.

[edit] OK only 130mA, you could run 7 fans.

Thanks deathray. but the transformer only has 2 lines, will this work?

Yeah, you've got two cords with two wires each, or two prongs and a cord with two wires.

Let's call it a power adapter instead of a transformer for the benefit of others so that they don't make the same mistake as you.

[edit] You only need two wires to hook up the fan: If it has a third yellow wire, that is for the fan speed sensor. You do not need it.

Just wondering but could the heat shield be used to completely separate the lcd and fresnals from the lamp? Seems like you could do this and install one fan to draw air across the LCD. The front part of the enclosure infront of the heat shield could have its separate fan and separate air intake to cool its section.

here is a post

Why not? Go for it. It is similar to what some have done before and I don't see any reason that it wouldn't work. I really don't see the need for the light box and third fan, but it's your design so have a blast.

I just increased the size of my air intake slot and was taking temperature readings. What I found was...weird. When the thermometer probe is dead center I found that my temperature was approximately 69-70F (@ lowest setting w/two evercools). While the side of the slot (where the probe gets mounted) reads 15-16 degrees F warmer. I wasn't using an air filter cloth before, because it'd over heat, but now I can. I'm thinking that the filter cloth will break up the air flow enough to cause more even cooling.

PS. I built a cardboard air filter box with the filter and opening approximately 3 inches above the slot and about three times the width of the slot. It makes it easier for the fans to pull the air through.

How am i suppose to hook up the fan to the ballast, i read the guide but the fan has 3 wires coming out of i, so i dont know which to connect.

Well if you've got a fan with three wires, then it is probably a 12VDC fan so you would need a power supply for it. Check this before proceeding.

You do not wire the fan to the ballast per se. It will share the same hot wire which will first be split to two switches and one switch will power the ballast/LCD power supply, the other will power the fan. The fan power will either go directly to the fan or to a power supply if it is a 12VDC fan. This info is in the guide. Perhaps you know someone who can help you with this.

No my grandfather is the handy one and he is even puzzeled by this one, theres no guides or anything on the forums because i cant find one, and i have no idea what the guide is talking about.

Im in the last stages of building and this is need ASAP any help would be greatly apperiacted. Thanks guys

-Joe

Did you read the guide? The diagram is fairly simple. What don't you get about this? Take heed to the warnings about the dangers of working with electricity.

Could the DPST switch in the diagram bellow be replaced by the lilliput on/off switch? It would be nice to turn the projector on and off with the remote.

Any ideas /concerns ?

(Wiring diagram borrowed from force617's post )

Your wiring diagram looks good.

I don't think that you would be able to use your monitor's power switch to control your projector's power. Most monitor controls are logic level controls that operate on millivolts so I can't see how you could make that work(maybe I'm not getting something about the liliput monitor). If you want to control your projector remotely, the best solution would be a X10 setup like foamcows is using.

I've just had an idea on how to add a countdown timer for running the fan after the bulb + LCD has been turned off. Digging through some stuff trying to find something I discoverd this:

an old mechanical timed charger for radio controlled car batteries, still works but current pulse peak chargers make it obselete, so I thought:

Take the timer mechanism out of the unit, attach the input of the timer to the 12v power from the cooling fan(s) and the output to a mains rated relay attached to the mains input of the 12v PSU powering the fan(s).

So, when you turn the bulb+LCD switch power off you then turn the dial to say 5 minutes, this activates the relay which keeps the fan PSU on, then you can switch the normal mains switch for the fan PSU off and the fan will keep going for another 5 minutes then completely turn itself off.
Oh and as a visual safety measure add a 12v LED to the output of the timer, so you know the timer is working and powering the relay which powers the 12v PSU.


Have I just re-invented someone else's 'wheel'? I think I'm going to have a go at doing this mod for my projector.

This is what I was initially thinking of earlier, except it won't work because if the lamp area is sealed off then there is no air comming in for the fans to suck out.

So I was thinking of this...

Ok I have absolutly no CAD skills so your just gonna have to imagine this one. Unless someone wants to sketch it up for me.

Anyways in my head I'm imagining a standard box layout, but in the back left corner (where everyone seems to mount their ballast) built a sealed mini box around the ballast. On the inside of the little cube put a fan sucking air in from the back, and have a vent for the air to come out of the side panel. Since the ballast is in it's own wooden box the heat from the light won't affect it and also no actual light will get in so you dont have to worry about light bleeding out either. And then there is a seperate fan to cool just the ballast. Hopefully letting it run cooler and more efficent

Now I think either run the tempered glass to seal off the light section completely. Have a fan in the bottom right section blowing air in, and another fan in the top left blowing air out. I think this would create a nice cooling pattern. Then cut the standard grove in the top between the glass and the LCD and attach a fan to the bottom to pull air through, hopefully cooling the LCD. Or you could have the fan blow air up from the bottom as heat rises, it may be more effective.

Also I was thinking a nice way to disappate heat from the lamp area would be cut a big square out of the lid leaving a 2 or so inch boarder to seal it to the sides. Now cover over the hole with aluminum from the inside (if there is a sealer that won't give off toxic fumes when heated then seal with that as well.) Then on the top get a peice of grating, cut it to 3/4(or whatever size wood your using) bigger then the hole on each side, then cut the corners, bend down a 3/4inch edge, and you have a nice flush grating, so you don't accidently touch the hot aluminum.


I know there would be 4 fans in that setup, but they could be smaller and lower DB since there are more doing the job. If not either of those, what do you guys think of the normal setup but with the ballast sealed and with its own fan. I think that would help with cooling alot.


Just brain storming, sorry for the long post. Please ignore if it all makes no sense .

I've noticed many people incorporating similar ideas. They build a small box outside of the box and put their ballast in there with some active cooling. With an electronic ballast many just attach them directly to the outside of the enclosure, thereby reducing heat inside.

A box "within" the enclosure sounds like another decent idea. As you mentioned, it would need its own cooling which would directly exhaust air outside the PJ enclosure. A good workable idea imho, not sure if anyone has tried it though (?)

http://www.nexfan.com/pccofanfaal.html

here is something that may be interesting to some, since many are using 12v fans.
what's even cooler, is that if this device trips a sound, then maybe it could be used to trip a relay to cut power to the ballast too!!! built in heat protector?!


(WOOOHOOOOOOOOOO -- post number 200!!! ) and the crowd goes wild!!! ................ummm crowd,........................CROWD????!!!! ..............is this thing on..........????

Thats pretty nice, darn cheap too. That can be used along with a thermometer w/built-in temperature alarm for a decent warning system:

http://www.bestbyteinc.com/prodinfo.asp?nu...aitem=6&mitem=8

or

http://www.gemplers.com/items/G76995.asp (thx moose)

has anyone found a suitable shroud for the fan? I would like to help quiet mine down, and I think a shroud around the bottom and sides would help out..

I have an AC fan, 120mm... something like 107cfm, which is probably overkill but I like it that way... I don't have to worry about overheating..

Anyone?

Thanks

If you want the ULTIMATE protection... WARNING is not what you want... you want the lamp to AUTOMATICALLY Shut off....
The ticket is to have a sensor circuit, like an Attic Fan sensor and hook it to a closed circuit relay that operates the LAMP.

Uhmm.. Let me see if I can illustrate it better.

In the drawing, you have your 115v circuit, an Attic fan control, and a normally "closed" relay.

You place the attic sensor (A) to monitor the air coming out of the "lens tunnel" (for lack of a better word). Set the temp at a level you feel would be dangerous to your LCD.
IF the FAN stops working for some reason, the TEMP will quickly rise and cause the circuit to "kick on".
This will activate the "normally closed" relay (B) and "open the circuit" thus turning the lamp off.

Just one way to protect your system.

If you really want "quiet", get like a 7" fan (176mm) and run it at like 1500rpm. You'll still have around 110CFM. You won't even hear it running at that speed.

How? With a fan dimmer switch of course.

Like this Comair Tarzan

You can pick one of those up on eBay for $20+shipping.

I thought sav8or1 asked a really pertinent question a few pages ago:

http://www.lumenlab.com/forums/index.php?s...indpost&p=42047

Basicly: Does it make sense that if you widen the cooling slot on top, you also need to increase the height of the cooling slot under the heat shield ?

Another way to put it: Is the smallest area opening the one that controls the resistance of air flow through the system ?

That should bring the physicists out of the woodwork . . . .

Also, another theory floating around goes like this:

If a fan makes a different pitch sound with the lid on vs lid off, it's airflow is being restricted. To unrestrict the airflow, widen the cooling slot.

If this is true, seems like a good experiment would be to remove the lid, grab two pieces of sheet material (plywood, lexan, baking sheets, whatever) and set them on top of the projector with a small gap between them. Move the pieces apart until the fans stop changing pitch. The gap between the two pieces is how wide the cooling slot should be. Make sense ?

I'd go do it right now except I'm on business travel.

Another theory I'm sort of mulling over is that moving the heat shield towards the back of the box, away from the LCD helps with cooling. I suppose if conduction through the air was the major vehicle for heat transfer this makes sense as the insulating layer of air is longer. I suspect that radiation also plays a large part though and radiative heat treansfer is not going to be affected much by this change in distance. Thoughts ?

Cheers,
- J

Hey Guys,
On the topic of neat and different cut off techniques for the lamp, I think I'm gonna try something I found at a local surplus store. For anyone in the twin cities, I found this at the Ax-Man in St. Louis Park, TexaTonka strip mall. It's a heater thermostat for a waterbed, I think Anyway, it's operating range is 70 - 100 degrees. My theory is to run the A/C for the ballast through a relay attached to it. If the temp exceeds the setting it opens the circuit cutting the relay, shutting down the lamp? Any thoughts? I was thinking in coordination with a attic switch it would be the perfect safety combo. It has a remote sensing bulb you could place close to the lcd panel... It was only $4.95... so can you go wrong!?

To date I have added a second evercool and increased the inlet as large as i can. My temps are still in the mid 90's. I don't like the temps but then I don't measure the temp the way everyone else does. I have the probe actually touch the monitor since it has a published max temp of 104.

My only other option is to increase the size of the 1/2" slot at the bottom of the tempered glass. Which, because of bad measuring during construction, will require me to route out a groove in the bottom of my box.

By the way, I think jshire is onto something here with his idea about fans changing sounds. mine definately whine more when i close the lid.

Is it just me.... or am I reading the wrong threads.... but I haven't seen as many post by "The Brain" He must be busy making sure the pro lenses are correct

The answer is Yes...and No. Think of it this way: If you try to suck air through a 1 inch pipe that is 2 miles long you will have an extremely high pressure drop across the inlet and outlet of the pipe. So you will have to apply more power to the fan. However, if you shorten the pipe to 1 foot, then the pressure drop will decrease substantially and you will not have to work so hard.

Conversly, if you increase the diameter of the pipe to 2 inches but still 2 miles long, you will decrease the pressure drop from the 1 inch, 2mile pipe, but may still have a higher pressure drop than the 1 inch, 1 foot pipe.

Simply speaking, the amount of air the fan can pull is related to the cross sectional area throughout the whole path, from inlet to outlet. I think you would essentially integrate the pressure drop per cross sectional area throughout the whole path. Keep in mind that pressure drop vs cross sectional area is a nonlinear relationship. As cross sectional area decreases, the pressure drop increases more or less exponentially (I think).

So the smallest opening does make a difference, but it is not the only factor in determining the amount of flow through the projector. In this case, a smaller opening at the bottom of the fresnal will momentarilly increase the air velocity at that point.

Another way of looking at it is that a large inlet and large opening will allow the most air to flow. A large inlet and small opening will allow the second most air to flow. A small inlet and small opening will allow the least air to flow.



True.

And yes... I am a research scientist.

SAV8or1,

Touch the monitor at a different point with the probe. Maybe the area you are touching is a spot were there is a lot of heat generated by the monitor and it is normal for it to be 90F at that point?

Also, the problem with a waterbed thermostat... is it applies voltage when the temp gets BELOW a certian level, not above...

I supposed you could power the light itself with it and as long as your temp was "below" 100, your light would have power. Though I don't know what kind of current it could handle. Any idea how much current a waterbed heater draws?

Yup, you're absolutely right. The circuit would remain engaged as long as it didn't hit the cut off temp. The switch is rated for 300 watts @ 120. I'm, going to use it to swith a high amp 12v relay instead. That way I don't have to worry about draw.

If your fan pitch increases a lot, then you have poor circulation in your case.

When this happens, the air pressure inside the case decreases and the fan begins to "starve" for air.

Because of the decrease in air pressure, the fans spin faster. PLUS the increase of the "pressure change" adds to the noise.

They did not do the math when designing the LL design. It calls for 1/2" under the lens housing... which gives you about 7 sq inches... That is NOT enough for 1-120mm fan. A 120mm fan is about 17+ square inches of fan area.

When you increase the resistance of your airflow with "obstacles", you should also increase your flow area to compensate.

I think the LL plans should revise it to AT LEAST 1".

My PJ will have a 2" gap under the lens housing, as I plan to have 2 fans.

Hope that helps.

[edit]And No... I am NOT a research scientist.

[Edit#2]Had my area wrong about the fan. It's around 17+ sq in.

You'll need a "normally open" relay then, opposite of what I have in my diagram. With power applied to it, it closes.
And when the temp gets hot enough to "cut off" that circuit, the relay opens.

The real trick is how accurate the thermometer is with "air", as it is designed to measure a more dense source, whereas an Attic switch is designed to measure air temp.

Let us know how it works.

My Temps are well with in range if I simply dangle the probe between glass and monitor. But the 90 degree temps are temps I have taken all over the monitor not just in one spot.

From what i understand...most people measure the ambient temp. I however am concerned about the surface temp. Believe me, those evercool move alot of air and work great.

For the air they move and the price, you really can't beat them.

Did we conclude and agree that a 120V thermal switch (attic fan switch) in a 12V circuit will work fine?

Do you have airflow on both sides of the LCD?


hanseneffects - I would say so. It would be easy enough to test. Hook a 12v adapter to it with a fan.

Air flow is only on the lamp side.

Seems I have read (through the sea of threads), that circulating air on both sides helped.

That would be my suggestion.

Maybe you could add a smaller (80-92mm) fan somewhere in the front side of your pj and have it pull air out of their as well. I'd say heat builds up in there as well. It would certainly be a lot easier than trying to "dig" out from under your panels... to allow more air through that passage.

I see your point. But for me "digging out" would solve another problem I have created by building a box thats too small. I can't get full fresnel coverage with the rear fresnel.

Another problem I am having is that I live in an apartment that has radiant heat. While this is great because I don't pay for heating, I actually have a hard time keeping my apartement cool. The ambeint temp stays around 78 to 82. Thats a little high and a little uncomfortable at times and obviously has an effect on my pj.

Some would say just turn it down... not that easy. changing the thermostat one notch takes anywhere from 12 to 24 hours to feel the difference. With the temp fluctuations outside it is easier to open a window

Hanseneffects,
You should have no problem running 12v through a basic attic switch like that, unless by chance your running some rediculous load through it, which I doubt! Perfect for relays though.

Agent707,
I may have been a bit vague on my explanation. I'm planning on building a double failsafe circuit that will force cooling with the lamp and continue cooling until the desirable temp is reached. The over temp will simply pass low voltage until it reaches it's temp (worst cae scenario) and opens the control circuit for the lamp. Check out this lame pic I drew to visualize it a bit better. I am concerned about the ambient sensitvity also though. I was cycling it on & off last night in front of the blower with the warmth of my hand.

I'm still going coo-coo with my cooling issue so I dusted off the old textbooks. Here's how I figure it:

Assumptions:
Evercool does not lie about their specs (non-conservative)
I am supplying the fans enough power (non-conservative)
All the heat is making it to the space between the fresnel and LCD (very conservative)
Relative humidity of air does not change (conservative)
Use average density of air
The 400 W also accounts for the ballast power draw (non-conservative)
AC/DC transformer 100% efficient (non-conservative)


Calculations
Volume flow: 2 evercools @ 100CFM = 200CFM
Average specific volume between 76 F (my ambient) and 90 F (what I would be happy with in the box) = 13.87 ft^3/lbm
Mass flow = volume flow / specific volume = 14.42 lbm/min

Entrance conditions:
76F
20% relative humidity
22.39 btu/lbm enthalpy

Exit conditions:
90F
20% relative humidity
28.18 btu/lbm enthalpy

heat transfer = mass flow x (exit enthalpy - entrance enthalpy) = 1468 W

PLENTY !

My heat load should be:

Fan 0.13 A
Fan 0.13 A
Lamp 3.33 A
LCD 1.2 A

Total 4.79 A (I'm going to go measure the current at the fuze with a meter to be sure)
Voltage 120
amp x volts = 575.2 Watts

heat transfer / load = 2.55

In other words, the system should be able to move 2.55 times more heat than it needs to in order to maintain the system at 90 degrees.

Conclusion: something is screwed up with my geometry. Gaps, leakage, etc.

I agree. I have 2 evercools(top mounted) and i am still in the uncomfortable mid to high 90's. I could care less about the math. Others do fine with one fan. I am suppossed to be moving twice the air with 2 fans. It is really FREAKIN agrivating.

But I'll truck on ang figure it out. But like I said, It seems as though it should work.