Hi all, first post here but I've been lurking for quite a while (only created an account recently though). I've already successfully put together one projector, but the bulb I used wasn't very bright so needless to say it didn't take long for me to want something better.
I managed to get my hands on a 150w par38 metal halide and ballast, so I've been doing some experimenting with that, but I'm having problems with heat. At the moment I have everything set up in isolated sections; there's the bulb housing, followed by IR glass (from DPC) about 3.5" away from that, a sheet of XL-10 lexan, then another 3" or so to the screen holder (5" PSone LCD for the moment). There is an 80mm fan (75 CFM max) blowing air between the IR glass and the front surface of the bulb.
I checked the temperature of everything before putting in the screen; it all seemed fairly low and there was no radiant heat escaping to the screen area at all. The IR glass was getting up to around 140ºF near the center of the bulb, and the lexan around 80ºF. When I put the screen in though (turned off), after about 5 minutes it was getting up to 130-140ºF, which is far too high for operating it. I tried putting another fan (40 CFM) blowing across the screen (perpendicular to it), but the temperature drop from that was nil.
Reading other posts it seems that people have gotten away with less cooling than this, so is there something I'm missing here? Would the fact that the bulb is in a par38 housing have a different effect on the amount of IR being sent towards the screen? Has anyone even read this far 😛? Anyways, thanks, and in the mean time I'll be trying other positions for the fans...
I managed to get my hands on a 150w par38 metal halide and ballast, so I've been doing some experimenting with that, but I'm having problems with heat. At the moment I have everything set up in isolated sections; there's the bulb housing, followed by IR glass (from DPC) about 3.5" away from that, a sheet of XL-10 lexan, then another 3" or so to the screen holder (5" PSone LCD for the moment). There is an 80mm fan (75 CFM max) blowing air between the IR glass and the front surface of the bulb.
I checked the temperature of everything before putting in the screen; it all seemed fairly low and there was no radiant heat escaping to the screen area at all. The IR glass was getting up to around 140ºF near the center of the bulb, and the lexan around 80ºF. When I put the screen in though (turned off), after about 5 minutes it was getting up to 130-140ºF, which is far too high for operating it. I tried putting another fan (40 CFM) blowing across the screen (perpendicular to it), but the temperature drop from that was nil.
Reading other posts it seems that people have gotten away with less cooling than this, so is there something I'm missing here? Would the fact that the bulb is in a par38 housing have a different effect on the amount of IR being sent towards the screen? Has anyone even read this far 😛? Anyways, thanks, and in the mean time I'll be trying other positions for the fans...