from Hacker News

DIY True 4K Projector

by humbfool2 on 6/15/20, 3:13 PM with 40 comments

  • by huhtenberg on 6/15/20, 5:36 PM

    Since the right people might be reading through the comments here -

    I've been looking at making a hi-res ceiling projector for a living space. Perhaps not one, but a set of several projectors with an overlap, but the key point is that they need to be placed in a way so not to interfere with the normal flow of life. Nor to be easily shadowed by people walking around, etc. This (likely) mandates placing them around the room perimeter, possibly on the walls at some height. This in turn means that they will be projecting at an angle.

    Do I understand correctly that it's not possible in principle to achieve proper focus on the target surface when projecting at an angle like this? That is if I am to project, say, a star field then it's not be possible to have stars close to the projector and far from it to be both in focus at the same time?

  • by cmurphycode on 6/15/20, 4:59 PM

    This is so awesome! Back in 2008 I built a projector from an old unsued laptop and a high powered metal halide overhead projector that I bought off ebay for 50 bucks. It was surprisingly good looking; I was very happy for the total investment. It was unwieldy and pretty power hungry, but none of that really mattered living in my college dorm at the time.

    When the laptop screen eventually gave up (I think just the connector) I never ended up rebuilding it. Nowadays you can get a really awesome looking projector setup for so little, it's not really worth trying the same approach.

    But from what I skimmed through, this is a build of way higher complexity, cost, and quality. I'm looking forward to watching this video tonight.

  • by bserge on 6/15/20, 4:41 PM

    DIY Perks is a fantastic channel. So much good stuff, so little time to try everything :D

  • by aidenn0 on 6/15/20, 5:00 PM

    When you buy an expensive projector you are paying almost entirely for brightness, so this result isn't too surprising.

  • by fenwick67 on 6/15/20, 7:00 PM

    The super low-cost version of this is a magnifying glass and a shoebox - it works surprisingly well if you're only throwing a few feet in a dark room.

  • by superasn on 6/15/20, 8:51 PM

    I never even knew Sony had released a 4k phone. What a clever way to kill two birds with one stone: Get an android system with a 4k screen but for 1/5th the price.

    This guy is a true hacker.

  • by pengaru on 6/15/20, 6:18 PM

    A bit disingenuous for the presenter to completely ignore the obvious vignetting of his dim projected image, the results seemed pretty mediocre from where I'm sitting.

  • by ktm5j on 6/16/20, 1:47 PM

    I built a similar LCD projector when I was in high school! Same basic principal as is used here, shine light through a bare LCD panel (mine was from a broken laptop), add some fresnel lenses and a focusing lens and throw it all in a box.

    Pretty cool, but just buy a damn projector. Do not approach this as something practical that's going to be useful, because it's not. It's huge, probably loud, you'll get dust and stuff stuck in all sorts of places messing with the image and it lacks advanced focusing like keystone transform https://en.wikipedia.org/wiki/Keystone_effect

  • by lmilcin on 6/15/20, 6:42 PM

    This is marvelous.

    Now imagine, with no right to repair, manufacturers locking all components making these things impossible.

  • by mleonhard on 6/15/20, 10:26 PM

    He mentions that adding a reflector to the LED will reflect too much heat onto the LCD. Could this be solved with a pane of glass between the LED and the LCD to absorb the IR light?

  • by netsharc on 6/15/20, 6:19 PM

    The audio seems to be a let down though: plug something into the (disassembled) phone's audio jack.

    I wonder if phones can deal with USB audio cards (that have surround options), or if there are any Bluetooth audio solutions that offer surround sound.

    Or I guess you can replace the phone with a PC/laptop, and have the display connected to an LVDS driver..

  • by chooseaname on 6/15/20, 4:48 PM

    Interesting. I’ve been thinking of trying to find a decent projector that operates off 12V for hurricane season. Something cheap because we’d not use it too often. DIY might be an option. I don’t have access to any way to make the metal panels like this one has though.