I'm still waiting for my lenses, and ballast, so I have nothing to run tests with. I am mulling over material placement considerations, and I was wondering if anybody had checked:
How hot does it get inside the box, at different locations?
Everyone has been sticking their thermostat near the LCD, because that is believed to be the most sensitive component.
But what about:
- Between the tempered glass and the lamp?
- Just above the ballast?
- Next to, but not touching the lamp?
- Behind the flashing?
- In the front of the box, where the circuit boards go?
If the new electronic ballast is placed outside of the box, does it require fan cooling? How hot does it get? Can it just sit out in the open? Given little children about, is this a good idea?
If placed in its own external box (because of the children), would I need a another fan, or can I just have grates to allow natural air flow?
Full Version: Temperature Questions
My ballast is outside the box, but I still need fan cooling.
well all i can say about this is that the new electronic power supply is enclosed in its own casing -
yes you still will need a cooling fan - the lamp gets hot
i have the old school power supply - but i have made it external - i made a little enclosur with no lid - i can say that thing WILL burn your hand (this is where most of the heat comes from) -
with that said i still have a cooling fan in my projector -
yes you still will need a cooling fan - the lamp gets hot
i have the old school power supply - but i have made it external - i made a little enclosur with no lid - i can say that thing WILL burn your hand (this is where most of the heat comes from) -
with that said i still have a cooling fan in my projector -
I believe he is talking about and external ballast only not a power supply, if it is external, i do not think the electronic ballast will get that hot like the magnetic ballast, will just have to ask brain, maybe when he gets a chance he can run it with the bulb unscrewed to see how it is. just have to see.
I realize that the pj will require fan cooling because of the lamp.
One of the things advertised about the electronic ballast is that it is modular, so it can be removed from the pj interior. If I put it outside, do I need a separate fan to cool the ballast, or is the heat sink sufficient to cool itself?
And does the electronic ballast get hot enough that I need to put it in some sort of shielded enclosure so little kids won't touch it?
One of the things advertised about the electronic ballast is that it is modular, so it can be removed from the pj interior. If I put it outside, do I need a separate fan to cool the ballast, or is the heat sink sufficient to cool itself?
And does the electronic ballast get hot enough that I need to put it in some sort of shielded enclosure so little kids won't touch it?
I'm also trying to figure out the scope of the heat generated by the lamp.
It has been stated that tempered glass is required not because of the heat, but because the temperature differentials between hot and cold cause annealed (non-tempered) glass to break.
It also has been stated that some have observed unshielded wood getting toasted, which implies that it is just shy of catching on fire.
Jones set up a light box which he had great success in cooling the internal box, but the front 50% of his enclosure is open. Stainless steel will transfer heat straight through, but not side to side. The aluminum transfers heat throughout, which spreads it out. It may be that the various metals and structures were acting as a big heat sink, and the fan was dissipating it successfully. (Think of a CPU heat sink and the fan on top)
This may be a key to better cooling. For example, we're trying to protect the LCD from heat, yet some people are using aluminum frames on their fresnels. That will transfer some amount of heat from the bulb side to the LCD side.
I'm also wondering if we can use lexan instead of ordinary glass, or even the tempered glass. It is lighter, less breakable, rated to high temperatures, and pretty easy to obtain. It is cheaper than tempered glass, but more expensive than annealed glass.
Most plexiglass have problems with long-term exposure to UV, but not Lexan. And if you add in the UV filter, you reduce even that. Lexan can block heat, acting as an insulator, dropping the heat around the LCD more.
The net effect is that if the interior of the pj is cooled more efficiently, presumably the electronics last longer, and the fans don't have to work so hard (you can use quieter fans.)
Anyways, they're just some thoughts.
It has been stated that tempered glass is required not because of the heat, but because the temperature differentials between hot and cold cause annealed (non-tempered) glass to break.
It also has been stated that some have observed unshielded wood getting toasted, which implies that it is just shy of catching on fire.
Jones set up a light box which he had great success in cooling the internal box, but the front 50% of his enclosure is open. Stainless steel will transfer heat straight through, but not side to side. The aluminum transfers heat throughout, which spreads it out. It may be that the various metals and structures were acting as a big heat sink, and the fan was dissipating it successfully. (Think of a CPU heat sink and the fan on top)
This may be a key to better cooling. For example, we're trying to protect the LCD from heat, yet some people are using aluminum frames on their fresnels. That will transfer some amount of heat from the bulb side to the LCD side.
I'm also wondering if we can use lexan instead of ordinary glass, or even the tempered glass. It is lighter, less breakable, rated to high temperatures, and pretty easy to obtain. It is cheaper than tempered glass, but more expensive than annealed glass.
Most plexiglass have problems with long-term exposure to UV, but not Lexan. And if you add in the UV filter, you reduce even that. Lexan can block heat, acting as an insulator, dropping the heat around the LCD more.
The net effect is that if the interior of the pj is cooled more efficiently, presumably the electronics last longer, and the fans don't have to work so hard (you can use quieter fans.)
Anyways, they're just some thoughts.
OK, let's see if I can get them all. The electronic ballast can be used externally without any kind of box. The wood is not actually toasted; there is never any 'roasting' going on. It is getting 'tanned' as any organic substance exposed to bright light will. We have glass and acrylic to block UV but in case we are worried beyond that we have a nice UV acetate to clean up anything that's left. The heat on the lenses is very minimal in relation to their design tolerances and the aluminum frame is certainly not going to exacerbate their degradation due to the forced cooling of the design.
I'm not a believer in plastics to replace glass. I have no special empirical evidence of this but I've seen plastics degrade in relatively benign environs. At any rate, try it and let us know
I'm not a believer in plastics to replace glass. I have no special empirical evidence of this but I've seen plastics degrade in relatively benign environs. At any rate, try it and let us know
Somewhere in the back of my mind, I'm thinking of making the box itself out of lexan. Paint the interior silver, then flat black, then mount flashing. By the time you're done, it will look like a Macintosh.
Obviously, this will have to wait until I get my first box together, because I think the types of measurements I'm thinking of, I'll have to do myself.
There are several points where hot metal and the bulb come close to the sides, or touch the box. Ensuring that those temperature points are well below the rating of the lexan will be critical.
I currently don't believe the size and look of the pj will pass the "living room test." That is, my wife will probably throw it out of the living room.
I'm doing the best I can to make the wood box look professional, out of a good quality wood, and will stain it to make it look like furniture. On the other hand, I chose the screen name "All Thumbs" for a reason...
Right now my concept of operations is like that of the old home movie projectors. Watch a movie, then back it goes into the closet.
Obviously, this will have to wait until I get my first box together, because I think the types of measurements I'm thinking of, I'll have to do myself.
There are several points where hot metal and the bulb come close to the sides, or touch the box. Ensuring that those temperature points are well below the rating of the lexan will be critical.
I currently don't believe the size and look of the pj will pass the "living room test." That is, my wife will probably throw it out of the living room.
I'm doing the best I can to make the wood box look professional, out of a good quality wood, and will stain it to make it look like furniture. On the other hand, I chose the screen name "All Thumbs" for a reason...
Right now my concept of operations is like that of the old home movie projectors. Watch a movie, then back it goes into the closet.
You can get all 007 and have it rise out of the floor or something.
There are a lot of options floating around in my head about what I want to do with my box. I am moving into a new house in a month and I'll have to see where exactly it will go etc, and I am still tossing around the idea of ceiling mounting, or building a piece of furniture around it.
What really got me going before I posted this was the thought of the ultimate "center console". Projector, mini-fridge, who knows, all built onto one unit, set up in the den, etc... Perhaps a panel of controls for everything in the room, including all lighting (including aquarium lighting), sound, whatever, built-in on the top near where an armrest would be..
Then there always is the thought of modifying something...I have 2 125 gallon aquariums on huge stands with tons of room underneath. One stand I actually built with a carpenter friend of mine, that looks nice and is nearly indestructable. That particular item could easily be modified.
Sorry to get off topic, the thought of rolling out the PJ and then rolling it away again is one that I want to avoid. I want to watch T.V. on this thing!
What really got me going before I posted this was the thought of the ultimate "center console". Projector, mini-fridge, who knows, all built onto one unit, set up in the den, etc... Perhaps a panel of controls for everything in the room, including all lighting (including aquarium lighting), sound, whatever, built-in on the top near where an armrest would be..
Then there always is the thought of modifying something...I have 2 125 gallon aquariums on huge stands with tons of room underneath. One stand I actually built with a carpenter friend of mine, that looks nice and is nearly indestructable. That particular item could easily be modified.
Sorry to get off topic, the thought of rolling out the PJ and then rolling it away again is one that I want to avoid. I want to watch T.V. on this thing!
...So I built the box, but didn't put in the lens yet. I did get a 11x14 piece of Lexan and set it up as a heat shield, about 7" from the bulb. Then, using a digital thermometer, I ran some tests.
First, I turned on the bulb/fan and sealed up the box, so it would be operating as normal. Again, I didn't have the lens or LCD in there (didn't trust it yet). I then waited 30 minutes.
1 inch above the bulb (not touching the bulb, but getting close) 236 degrees F
Norpro Reflector (covering half the bulb) 98 degrees F
Behind Aluminum Flashing, and reflector 87 degrees F
7 inches in front of bulb and reflector, dead center, in front of heat shield 100 degrees F
Other side of Lexan 93 degrees F
Electronic Ballast (original, outside of box, no fan) 102 degrees F
Conclusions:
The Norpro reflector reflects much of the heat as well as the light.
The area behind the Norpro and the flashing gets very little heat. Some people hide wiring behind here. It is well protected.
I was skeptical that I could replace the tempered glass with Lexan. In fact, the Lexan can easily handle the temperatures I saw.
The electronic ballast is hot to the touch, but it won't burn you. If you enclose it in wood (a second box), you might want to consider ventilation.
First, I turned on the bulb/fan and sealed up the box, so it would be operating as normal. Again, I didn't have the lens or LCD in there (didn't trust it yet). I then waited 30 minutes.
1 inch above the bulb (not touching the bulb, but getting close) 236 degrees F
Norpro Reflector (covering half the bulb) 98 degrees F
Behind Aluminum Flashing, and reflector 87 degrees F
7 inches in front of bulb and reflector, dead center, in front of heat shield 100 degrees F
Other side of Lexan 93 degrees F
Electronic Ballast (original, outside of box, no fan) 102 degrees F
Conclusions:
The Norpro reflector reflects much of the heat as well as the light.
The area behind the Norpro and the flashing gets very little heat. Some people hide wiring behind here. It is well protected.
I was skeptical that I could replace the tempered glass with Lexan. In fact, the Lexan can easily handle the temperatures I saw.
The electronic ballast is hot to the touch, but it won't burn you. If you enclose it in wood (a second box), you might want to consider ventilation.
What are the acceptable temperatures in various parts of the enclosure?
Shouldn't go over 150º in the light compartment and stay under 90º between the panel/glass.
Shucks! My glass-lcd temperature is around 98. I guess that is too hot!
Put the probe directly on the panel. I've found that the glass/frez will exibit a higher temp than the actual panel temp.
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