17 inch 16:9 assault on high end project

[Guy Grotke]

>Is it true that beter results are obtained with a matched pair back to back?

For our projectors, the "matched pair" is really the condensor fresnel and the field fresnel.

In the drawings you may have seen of a matched pair condensor system, the first lens collects a lot of light from a point source at its focal length and refracts it to be a parallel beam. The second lens refracts the parallel beam to a point at its focal length. That is not what we do with our pre-condensor lens.

Instead we are just trying to collect more light by putting it as close as possible to the lamp, and then refracting that light into a cone that matches the cone the condensor fresnel would see from a lamp at its focal distance.

[Goemon1966]

Guy,

So, in addition to the 2 fresnells, I need just the one condenser?

Ace was extolling the virtues of dual pre-condensers, but I would thrilled if I only needed the one as the costs of this projector down under (here in Australia) are quite high.

Its crazy - we can't get a coil ballast for less than $200 let alone any of the other technology.

Anyway, a single pre-condenser would be good news indeed.

Regards,

G

[Hezz]

Goemon,

Ace was using two condensers in an attempt to improve the light gain in his light engine but it is not a necessary thing nor probably the best thing to do for someone putting together a DIY projector for the first time.

Hezz

[Hezz]

Guys,

Today I bought a new Onkyo A/V receiver so that I can integrate the HTPC more full into the system. It has multi channel analog inputs and digital inputs which my old A/V receiver lacked.

Still working slowly on the projector frame. Next I need to build LCD mounts.

Hezz

[Rox]

hi friens;

i never have seen results using 17" and 135 triplet, Nobody knows the FOV of this lens. The only results i have seen, shows it is not posible (or could be a bad configuration but i don´t think this way).

Could someone do a test with this lens? i would like to measure an angle, just a laser is needed (it is not the FOV but we can have an idea of the FOV. Just measure the max angel the laser gets out trough the lens. I´ll do the same with 32cm focal 80triplet. And we can compare the results.

somebody interested?

[Hezz]

Rox,

If you are talking about the DIYprojectorcompany 135 mm diameter lens which has 450 mm FL. It most certainly will work with a 17 inch LCD. I have tested it and I believe it will work with a 19 inch also.

Allen has tested the lens with a 17 inch mockup. IF you visit the forums on DIYprojectorcompany you can find the thread with the information. We do not actually know the field of view but this is a somewhat subjective thing because a lens is usually designed for correction within a target FOV but it can still often perform outside it's optimum FOV with lowered resolution at the edges.

The FOV on this lens is quite wide. I would estimate it at 35 - 40 degrees. This is the best lens you are going to get for the money for a 17 inch LCD.

Hezz

[Rox]

i don´t like his test. How did you meassured de fov?

[Hezz]

Minor update on projector:

I have built the base out of MDF and have the frame mounted on the base. I just ordered my USHIO 250 watt bulb and I fould out as an added bonus that it has UV blocking quartz glass.

I finally figured out how I am going to get the patterns for the deep parabolic reflector made. I found some software meant for boat hull repair or building which can take a solid model and extract a 2D pattern from a curved surface. Actually there are two different programs that do this but the approach is different. One is a Rhino plugin. The other is a dedicated program. I will import an IGES file of the solid model and then create a NURBS surface in the software from the IGES model. I can then flatten out the NURBS surface to get a very accurate flat 2D pattern of each reflector side.

I have been modeling a new two piece reflector/heatsink combination and I need to get the exact bulb in my hands to get all of the measurements that I need to complete the design. Then hopefully in a couple of weeks I will have the final reflector/heatsink designed.

I am planning on using an Edmonds optical piece of heat glass. The lower grade costs 24 USD in rectangular piece that something like 102 x 127 mm in size.

I've also decided to buy a custom first surface mirror and use the aluminum mirror that I started making for the mirror backing plate. I think it will cost more for all the materials to polish the mirror than to buy one. Plus it makes the mounting much easier.

I need to glue the mirror to the aluminum backing plate. I think slilcone would be good.

More pictures are in the works once I get some more work done.

Hezz

[chbright]

tiger direct has a good deal on a hyundai 17in panel, the rebate lasts till 5/31/05.

rebate

panel

my dad has the 19inch version (with dvi input) and it is absolutely amasing, it is a lcos panel though would that effect anything?

[Hezz]

HTPC meltdown,

Well it actually happened. I had a heat meltdown of my HTPC. I suspected this would happen when I first bought the Antec Overture case.

Note: I do not recommend this case for a HTPC if you are going to do games or run dscaler.

This is a good looking sleek and quiet case. When I first bought it I needed a quick and resonably priced case for my HTPC that would kind of blend in with the HT equipment. When I opened up the case for the first time I noticed that it was going to have some heat issues under heavy loads but I liked it's quietude so much that I kept building and experimenting.

This case is unusual in that the PS is up front and sucks air in. It seems to work from a low noise perspective but the case fills with warm air from the PS unit. There were to other quiet venting fans so I thought that all would be Ok.

The HD's are mounted near the back exit fan supposedly to cool them. The only problem is that they are being cooled by really hot air from the PS and the CPU which is right next to it. IT's a bad design for cooling issues without some modifications.

After running dscaler for about half an hour the HTPC started spontainiously rebooting. I then think the HD data became corrupted as the OS won't boot at all. I'm hoping there is no hardware damage.

I have decided that I need to take a more industrial approach an build the ultimate long term HTPC case. There is only one case that I would consider and even most 250 USD cases are not adequate in my book.

So I am going to embark on a high end home made design which is a hybrid approach of heat pipe technology and slow turning fans.

Here are models of my work so far. The heatsinks are large homemade units made from machines flat plate and rectangular .5 x 1.5 inch extrusions. There is no HD mount as of yet as I am thinking about how I am going to do that.

Hezz