Ok. After blowing out the LCD in my first plog (see signature) I decided
it might be best to start off a little smaller. So my parts list for the next pj
are as follows:

PSOne 5" LCD Screen
3M 9200 OHP

That's right, true junkyard DIY. I'm going to rip apart the 3m for light's, mirror, fresnel and triplet.
Need a few pointers on a folded 5" design. Can't seem to re-locate that post from the other night
that showed the layout. Wish me luck!! (I think I'll use lego's and pegboard for mock-up)

Try this one buddy.. PS ONE PJ

Check this one out also PSONE PJ

Thanks Menik. I had been trying to relocate one of those threads. Wish me luck!

I'm having a tough time with focal lenghts. I want to just rip up my 3m 9200 OHP for a psone. Should I just measure the distances as the fresnel and triplet are already mounted? I guess I'm missing something because when I take the fresnel and triplet out I get completely different measurements.

Here are the measurements from the 9200:
Click to view attachment


When I take the fresnel and triplet out and use the "Sunlight" method I get a FL for the
fresnel of 5.5 inches and the triplet is 8". Plus it only has one fresnel in it but has grooves
on both sides (thick, dense grooves on one side and light, spread apart grooves on the other)
It's not two fresnels glued together its one peice of plastic grooved on both sides. When using the
sunlight method though I can't get a single point of light unless I stick a flashlight directly on the fresnel
and triplet. Somebody help me out. This always looks so easy in other peoples plogs!

edit: Oh, I almost forgot, the lamp is angled down at the mirror about 35 degrees so I'm thinking they're getting
a 90 degree bend after also tilting the mirror the other 55 degrees.

Giving up on the ohp fresnel. Will go to OfficeDepot tomorrow and snag some page magnifiers. That's mostly what the psone guys are doing I suppose.

Well, I'm glad my mistakes don't cost much. See whats wrong in this picture?

Click to view attachment

Bye Bye PSONE. (The other 3 are cowering in their boxes like turkeys at Thanksgiving)
And since this just so happened to occur when I was hooking up the A/V cable it also fried my
DVD player. I think the warranty is still good though.

Word to the wise.....Use wood for everything!!!

edit: Warranty not good - add $85 to my "lesson Learned" total

Things might not be all that bad...Though that does look bad...
I was thinking of making a mini pun15her box with a psone screen, so I've been looking for the pinouts of the connectors and I came across this:
http://www.extremetech.com/article2/0,1697,1765358,00.asp




Worth a shot...even if you do have extra screens...

Thanks for that info Limbfilter. i'll have to try that, nothing to lose on that controller anyway. Screen still works though. tested it with another psone controller board and it checked out ok. I've moved into the design stages on my psone and I can't decide between two of these designs.

This:Click to view attachment

Or This:Click to view attachment

The fresnels are Office Depot page magnifiers and are supposed to have a 310mm focal length.
I like the second one better because there is only one mirror but the double fresnels between the lamp and the lcd I haven't seen results from yet, only theory. Someone said in a post that they had used this method on their psone but I never saw any images from that. I've tested the triple fold method by laying the fresnels as positioned and can get an image of the lamp (ohp FXL) and its reflector on my cardboard screen. Problem is with the office depot fresnels my triplet no longer matches up. I don't understand that either, does the triplet have to match the focal length of the field fresnel? Also if anyone can verify that the doubled up fresnels actually cuts the focal length in half I'd appreciate it. Thanks everyone.

Hi Manshack one,

I like the second design best, like you say only one mirror. Also the position of your light, I've recently found that when using an OHP light it's important to maintain the original airflow around your bulb. I believe the second design would allow for that.

Also if you have an ohp whay not use the fresnels from that? Cut the two fresnels apart, I tried that before buying the kit, they're just sealed at the edge and should cut fine with a rotory tool

Spatula,

The reason that I didn't want to use the ohp fresnel was because I couldn't figure out
the focal lengths at first. But after blowing the psone and dvd player I forced myself
to slow down and think a little more before jumping ahead like that. I realized that
the measurements had been right in front of me the whole time in the first ohp layout pic
in this thread. 12.5" from lamp to fresnel and 18" from fresnel to fs mirror. So that's when
I took to trying out the 2 other designs for making this all fit inside of a pc case. Problem was
the focal length of the ohp fresnel (and the office depot fresnel which has the same 12" FL)
was putting the lcd sled in a weird position because of the 2 bends. Long story short I came
across a thread about multiplying fresnels and someone mentioned that they had done that for the
psone to make the image brighter. So I went ahead and cut the ohp fresnel down to size and
binder clipped it to my office depot fresnel. That operation should effectively cut the focal length
in half allowing me to move forward with the 2nd design with only one bend. A psone vertical in a
computer tower case. anyway, after cutting it down and clipping the fresnels together I started
measuring again and it seemed like everything was going to work out so i layed some little wood
slats down, hooked up the second psone and fired it up for a test run. Here's that result:

Click to view attachment

Proof that the psone pc pj can work!! I know everything is horribly aligned and there's only half a picture, and that I was having to hold the triplet in place but it's an image dam*it!! And after burining a 17" lcd and a psone and a dvd player it was sweet enough for redemption for me!

Here's how it's looking:

Click to view attachment

I still have to build a sled, do the vga mod, build the focus box, build the heat shield box, wire everything up neatly and cover all the light leaks. But even with all of that to do I still could have stood there holding that power button and the triplet for hours seeing that image on the wall.

Oh, i forgot to add that I couldn't split the ohp fresnel. It's one peice of acrylic that they put grooves on both sides of. i call it a 'dual focus fresnel'.

Cool, just thought I'd mention it, I like the idea of getting everything in a pc case too. I'm really interested in doubling up the fresnels as well, I want to build a smaller projector next. Can't wait to see your results.

What, you mean you wouldn't watch that image for hours!?
Haha, just kidding. I can't wait to see my results either. I need to take a sick day or something. Thanks for the confidence boost too!

Ha! I know what you mean, I always want to leave work early or not go in so I've got more time to work on my projector

You should be able to set up a good focus unit in the cd rom bays of the pc tower too, not that I'm having a go at your method of holding the triplet by hand of course, that creates a fantastic picture.

Holding the triplet by hand is nice but it gets a little warm if you leave your hand in the light path too long. I'm building the focus mech out of the hard drive cage because the triplet fits real nice in it and because the hard drive cage fits almost perfectly into the cdrom cage. Bottom line, I think pc cases make great pj cases for psone's. But then again, i haven't had an image on the wall for more than 2 minutes.

You'll get there dude, don't worry.

Been putting some time in on the pj and thought I'd run a few updates on my plog.

The second version of the pj seemed like a good idea but the lamp is just too close to the lcd. Keeps getting burned in. It's like watching paper get burned in the middle. I'll have to add a second mirror but it won't be like the first diagram above. It'll just be 2 mirrors with 45degree bends. This will also help because I can possibly fit a small power supply in the case to handle the fans. Either way, it's still coming along. I really need a solid answer on these Apollo page magnifiers focal lengths though. Everyone seems to add in "about" when they describe the focal length. I guess i've got some more playing to do before it'll be ready to get bolted down.

Here's what my psone pj is going to be like (like it or not)....


Click to view attachment

Of course, this still needs tidying up.

Things to work on:

1) Cooling - This setup solved my burned lcd problem but now i have a new one - How do i keep the heat down now?

2) wiring

3) Bolt everything down so when it's vertical nothing crashes into the bottom

Could you get rid of the back mirror, aim the bulb towards the lcd, put a fan to blow across the bulb and a piece of lexan that would seal the bulb from the rest of the pj. This is unless you need the mirror to add the distance to get the focal length.

Thanks for the response BoomerBrian. I actually tried that method if you'll look up at the second pic in post 11. I really wanted to do it that way (with the bulb on bottom pointing straight up) but even with the lexan there I get too much heat on the lcd. I had doubled up on the fresnels to shorten the distance so could put it that way. Since it kept burning my lcd in i had to move the lamp back which meant second mirror had to go in. I wonder if i could move it back that way and just build a light engine enclosure with tempered glass and lexan. The picture sure was a lot brighter with the lamp only 7 inches from the lcd.

I think I would go more for a piece of optic glass, possibly even one thats blocks IR or UV. Im not sure the lexan will stand up to the temps above that lamp. You might end up with a gooey mess. Even if you flushed the inside with wood, you would still stand a better chance with glass.
If you use an IR reflective glass, you could place the lamp back to where it was in its brighter position.

Still, its pretty neat!

Samurai, do you mean tempered glass? if so, how thick should it be?

I was thinking of trying the heat shield that joe built for this 7"

http://www.lumenlab.com/forums/index.php?showtopic=4114

Is there anything I can put between the lamp and the pc case to keep it from getting hot?

Hmmm. I think you may be right. I wasn't thinking about how hot those little bulbs burn. I was hoping that with the fan blowing across the bulb the lexan would hold up but probably the IR glass would be a better route. Off hand I don't know what temp the lexan will hold up to.

manshack_one, That light box looks pretty good. If you built that then that might solve your issues. Joe was also using an ohp bulb and didn't seem to have any heat issues.

SamuraiJack, Does tempered glass reflect IR or would he need to buy a special piece of glass to do that? I have never used tempered glass so I am not for sure.


I found the answer to my question.

XL10: This is a UV blocking lexan. This is probably the most common method for blocking UV light from the bulb and providing a heat shield for the rear fresnel and monitor. Most people get this from their local Home Depot and it usually costs around $10. The main advantages of XL10 are that is cheap, blocks UV, and can easily be cut to the needed dimensions at your own home. Just make sure when framing the lexan to leave a little expansion room for when the lexan is heated.

Tempered Glass: Other members use tempered glass as their heat shield. Since the tempered glass doesn’t block UV, a filter must be purchased from Lumenlab to block UV. Another hassle is you have to go to the glass store and have them cut it to size for you, so you better know the exact dimensions of your box. The advantages of tempered glass are that it doesn’t bow when heated, and it blocks heat a little better.

You need tempered at the very least if its too hot. They do make tempered glass that can block heat which would be perfect for you. Thickness is a matter of convenience and price, but I would try to steer towards a standard thickness. If you get it too thick, it might distort a bit.

The enclosure would do well for you if its done right. Make sure that when you cool it, you are venting directly outside from the chamber, other wise you will pull in heat and it will have a chance to settle into your box. With a PC case. You could section the bottom off with glass and use a few fans to get some very nice flow in that chamber. Shoot this makes me itch to do one myself....

Samurai, don't do one yet! I'm trying to be original.
Just kidding, this is a forum for sharing ideas so I can't
claim intellectual property on this one. I think i'll stop by
the glass shop during lunch if I have time. Sounds almost
like I need clear oven door glass. Could I also leave the lexan
that I have in there now but move it closer to the fresnels to manage
my UV protection?

You could leave the lexan in there but it would have to be on the cool side of the glass. Remember that each time your light enters or exits a surface you loose some lumens, so you want to have as little glass as possible and your glass should be as transmissive as possible. With enough airflow you should be able to get away with tempered glass.

I'll check with the glass shop and see what they have. I'm determined to put the lamp back under the lcd and take that mirror out. I hate to keep changing my mind but it was so much brighter with the lamp 6 inches closer. I'll build the enclosure out of flashing like Joe did and try to make a mount on the front like his. (hopefully he hasn't patented the idea by now The enclosure will run along the entire length of the bottom of the pj with the stock ohp fan blowing air across the bulb and out the back where the card slot covers are. What can I put on the bottom of the pc case to keep the case from getting hot?

Try the venting first, then if you need it, you could always pad it. Flashing is good as long as you keep some distance between the flashing and the outer wall.

The glass hest sheild that he used is from a shop light. I tested four heat sheildes the other day the shop light glass was vary good. the test was.

1) China heat glass 148 deg from a shop lamp
2) Buhl heat glass 140 deg from a 1000 watt pj has a slight tint
3)Clear temp glass 157 deg from the work plate of the BUHL PJ

I used a 250 watt lamp at 8"

Well, let's make sure this is going to be ok. It's a 400W Halogen OHP lamp that the glass will be 2 inches away from. It's gonna get pretty warm.

I'll be using the stock OHP fan. It really blows. (pun intended)

Yep AV has it right.
I was lucky enought to find a piece of glass that went over a 300W halogen bulb for outside use.
Later on I found one of the same lamps at home depot for 9.99. You could try them...

I found this light at the HD...The glass in front is identical to the glass I used.

Sorry, should have known that link would not work right. Goto HD and follow this path:
Lighting & Fans > Area & Security Lighting > Halogen Lights

For a small panel PJ the rear Fresnel of 300mm is to long. For a 7" panel a rear Fresnel of 150mm would be better. Instead of using double Fresnels on the rear or trying to find a 150mm Fresnel try this.
Buy a 220mm fresnel from LL or someone they can be had for $20.00 use it as the front fresnel this will be to short to reach the triplet so to focus the lamp you will have to move the lamp 110mm closer to the rear fresnel.

Perfect the PJ will be much brighter now. In short I think two 220mm Fresnels would be best for a 7" or smaller LCD.
Feel free to disagree.

Not to sound like a skeptic, but will this work??
effectively, what is this doing to the light path??
making the divergence of the light cone NOT a point???, thus moving the FP out farther????

Ricoks

what would be really cool, too, is if you make it a tad tighter inside, and then add a small MB inside (mini-itx??_ ) and then you could put in a small DVD drive (slim line slot load, like from a mac) and you'd have a computer AND PJ all in one fairly small package. maybe a Full tower would be better suited for this then.
hmmmmmm - got me thinking now for MY PS sitting in the closet stripped, ready for mounting.

Ricoks

Got my tempered glass last night. It was attached to a 300w halogen floodlight at walmart for $7.44. 1/4" thick. Also got an email back from 3m that says my 9200 OHP stage glass is tempered. Well, at least I don't have to cut the halogen glass, it's already small enough. I'll run a test later tonight and see what I get.

Can you guys help me check my math on this one:

Click to view attachment

The fresnels are 7.5" from the bulb. I am using the office depot page magnifier in front of the ohp fresnel. Rough sides are facing each other. The other side of the ohp fresnel has grooves also which i measured to be about a 16-18" FL (measured from ohp stage to triplet). There is a 1" gap between the fresnels and lcd. I just laid these out on my table because I wanted to double check the measurements before bolting it all down in the pc. I have room for 24" of light path in the pc give or take about 2 inches. Maybe someone else has multiplied fresnels to get the lamp closer for extra brightness and can impart some wisdom on me.

Here's what I came up with for a heatshield. Air from the front of the pc will be pulled in by the 65 cfm 120v fan, blown across the bulb and out the slots in the back. The glass is from a 300W halogen floodlight.

Click to view attachment


Even with this setup i still burn in the lcd. i'm going to try it again with a freakin' box fan running on this thing and see if it still burns in. Any other ideas for cooling this?

Here's another shot.

Click to view attachment

You could try this
http://www.surplusshed.com/pages/item/m2407.html
They say
Assembly includes a Halogen 300 Watt, 82 Volt GE #EXR projection lamp (used in Kodak Carousel slide projectors), a dichroic mirror, 50mm x 45mm x 2mm thick, and a DCX condenser lens, 50mm wide x 55mm long. The mirror passes the heat straight thru and reflects the light thru the condenser lens.
$15.00 I donk know what the shipping is.

Click to view attachment

So, how close do you think i could get the light to the fresnels using that?

Your rear fresnel would have to focus at the focal point of that thing's lens. Since it's for a slide projector I'd say it'd have to be right against the thing.

I was under the impression that with condenser lenses I could eliminate the lamp side fresnel and just have the triplet side fresnel? Don't condenser lenses do the same job as a fresnel which is make the light parallel?

Pretty sure that would be the case if that lens was as big as the panel. I'm not 100% sure though.

This light engine should work if the condenser lens does not have too short of a FL then it will let you put it closer to the rear fresnel the rear fresnel focuses through the condenser lens just like adding any two lens. The main thing is the dichroic mirror will reduce the heat by 85%.
There is a chance that the light could be so good [a round and even 7" circle of light] that the rear Fresnel could be eliminated.
A link on cold mirrors.

http://www.rocoes.com.tw/20040811/english/coldmiro.htm

Because the light is now cool you can place the condenser vary close to the LCD . You have four ways that might work no rear fresnel one fresnel two fresnels and no condensor at al,l with just the mirror the heat problem will be gone

Do i still have to handle the heat that passes through the mirror? Haven't read up on cold mirrors yet.

E = mc(mc)

Yeah, the energy goes somewhere. The heat is still there it's just not directed at the LCD.

so with that condenser lens, does it act like a spot beam or is the light coming out cone shaped? Since it's built for 2" slides does moving it farther away mean the light area gets proportionately larger?