68kMLA Classic Interface
This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.
| Click here to select a new forum. | |
| Driving an LCD bright white from a gizmo for use as a light table? | |
| Posted by: Trash80toHP_Mini on 2021-07-19 10:04:12 I've been doing nothing for quite some time, but thinking of this little project. Using a computer to drive the LCD seems a big waste of power. I've got VGA and DVI inputs and a powered USB hub for juice I think. Nifty panel with the PERFECT base for this application. I have a lot of contact sheets and negatives to ransack for scanning. | |
| Posted by: max1zzz on 2021-07-19 12:06:14 I have no experience with doing this, but a little bit of googleing turned up that (to my surprise) a arduino can be used to generate VGA signals using a library such as this one: https://github.com/smaffer/vgax The colour pallet is limited (And changes depending on how you wire it) but since your just wanting white it shouldn't be a issue | |
| Posted by: davidg5678 on 2021-07-19 14:02:01 I would take a look at this video: I think that it should contain the information you'll need to run the backlight on a TV/monitor LCD panel without providing a video signal. | |
| Posted by: Trash80toHP_Mini on 2021-07-19 16:09:59 Neat, I'll take a look at that for a larger panel that's useless as a display. Max, I was thinking more along the lines of driving the VGA interface's RGB lines full blast via resistors from USB power. 😬 | |
Posted by: max1zzz on 2021-07-20 09:18:40Max, I was thinking more along the lines of driving the VGA interface's RGB lines full blast via resistors from USB power. 😬That was my first thought but (presumably) you need the vsync / hsync to actually get a image, and by the time you have built a circuit to do that you might as well have just got a £4 arduino Uno clone 🙂 | |
| Posted by: 4seasonphoto on 2021-07-20 10:54:05 Maybe remove the LCD and just use the backlight + diffuser? Hopefully illumination is pretty even. My old 24" iMac had brightness which was about 1 stop brighter on one side of the panel than the other!  If you're only working with black and white, even something like this inexpensive panel would likely be fine: https://www.bhphotovideo.com/c/product/1434767-REG/huion_l4s_led_light_box.html | |
| Posted by: Trash80toHP_Mini on 2021-07-20 19:51:06 THX, I've already stripped the LCD out of a larger panel and it lights up briefly, then turns off. I'll get at that later on. Wrote this reply this morning, but forgot to hit the post button . . . oopsie! re: syncs Yep, it didn't take long to figure that one out Max, that's why the ironic grin emoticon. For the time being. Good 'ole 12 year old HP_Mini doesn't draw all that much power so a white pic to display full screen via the VGA input will do the trick. Driving the larger panel in backlight sheet only mode will be the most efficient setup by far, so I'll skip the Arduino sideshow. There's quite a bit of info out there about repurposing displays as light boxes. | |
| 1 |