EEVblog 1700 - Do Dumpster LCD TV's Make Good LED Light Panels - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: August 08, 2025, 10:00:59 pm
content: Can you convert a dumpster LCD TV into a light panel?HP320 Spectrometer:https://s.click.aliexpress.com/e/_okJifdp

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 09, 2025, 02:16:16 am
content: I spy a cane hanging from the fire sprinkler pipe?!Good video Dave, very informative. I wouldn't have minded the extra length if you went more into the "light" side of things.Like, why have a high color temp (thus more blue), only to filter the blue out?

author: EEVblog
author_rank: Unknown
timestamp: August 09, 2025, 03:07:25 am
content: Quote from: ballsystemlord on August 09, 2025, 02:16:16 amCame with the dungeon.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 09, 2025, 07:54:41 am
content: If that panel has a polarizer foil, I'll try to peel it off, to maybe foul around later with it (polarized light and such physics experiments).

author: jnk0le
author_rank: Regular Contributor
timestamp: August 09, 2025, 10:40:52 am
content: 20:30 - you can't reliably light up those edge lit diffuser/guide panels from the wrong side. Rotate it and you will see why.

author: golden_labels
author_rank: Super Contributor
timestamp: August 09, 2025, 04:26:15 pm
content: Reminds me how I had the same idea, more than once. I learned my lesson.It’s not only color issues: LCD panels have horrible efficiency as general light sources. If one wants a heater with a light function, they should grab an incandescent lightbulb.

author: Brumby
author_rank: Unknown
timestamp: August 10, 2025, 01:06:27 am
content: I found a good use for a couple of the LED strips from a backlit TV. They are mounted underneath my bench top.Having a low profile and integral heatsink, they are completely out of the way and together with a simple PSU and convenient switch they give me great illumination when I need to go fishing for items that make their way down there...(which seems to happen far more often than I'd like.)

author: bitwelder
author_rank: Super Contributor
timestamp: August 10, 2025, 11:30:29 am
content: So, CRI of the backligthing is about 75.What would be the CRI of a working TV set to a full white screen?

author: jh15
author_rank: Frequent Contributor
timestamp: August 11, 2025, 02:59:23 am
content: If I had a new really thin LCD/LED set, I would not run at 100%.Due to overdriving and poor heat sinking.Everyone is bulimic.

author: thm_w
author_rank: Super Contributor
timestamp: August 11, 2025, 09:54:07 pm
content: Quote from: ballsystemlord on August 09, 2025, 02:16:16 amNormal color temperature of LCD is 6500K. So 10K is not crazy high. I think most backlight LEDs are 8.5k to 10K range.Then there could be some extra blue attenuation in the crystal or color filter layers, seems to be the case for TN and IPS:https://opg.optica.org/oe/fulltext.cfm?uri=oe-21-22-26269&id=270066Quote from: bitwelder on August 10, 2025, 11:30:29 amSome LEDs I found were 80 CRI: latwt470relzk maybe some are better or worse.I tested on two monitors here and the CRI was 80-82, so basically its the same as your backlight LED, which makes sense. The color temperature will be lower, as the monitor is calibrated to 5000K or 6500K etc.

author: golden_labels
author_rank: Super Contributor
timestamp: August 12, 2025, 08:52:50 am
content: I believe that 2023 video(video1)is relevant to ballsystemlord’s question.(video1)3blue1brown “This tests your understanding of light | The barber pole effect”:

author: Kleinstein
author_rank: Super Contributor
timestamp: August 12, 2025, 03:31:44 pm
content: There are some TVs and LEDs that have an aging problem with the LEDs that causes them to get more blue over time. So the high color temperature could be an issue from age too. I send a TV to recycling because of the very blue tint it develpoped. So there is a chance than old TV can be bad because of the LEDs.An issue can also be the power supply. The SMPS may be combined for the light and display electronic. It may support reduced backlight but not necessary removing the display/receiver part.

author: Simmed
author_rank: Frequent Contributor
timestamp: August 12, 2025, 04:08:27 pm
content: Quote from: golden_labels on August 12, 2025, 08:52:50 amthat is fascinatingi wonder is there a known length + sugar concentration etc etc parameters = the end "hue" produces a constant color/hue which can be used repeatedly and accurately for calibration of colors ?

author: golden_labels
author_rank: Super Contributor
timestamp: August 12, 2025, 08:23:38 pm
content: Quote from: Simmed on August 12, 2025, 04:08:27 pmIf you are asking about this particular method to produce single peak at a particular frequency (color): from what I understand, no. Unless there is something very wrong with my understanding of the process: it’s obtained from white light and the result still contains all the frequencies. Some are just attenuated. You can see it from the output in 3blue1brown’s video appearing pale.If you ask about verifying that a monochromatic source is at a particular frequency: an opposite problem is being studied, with some success. It’s possible to get good enough calibration to measure glucose level from how much it rotates polarization plane of light. Even if light is scattered by skin. Search for non-invasive glucose measurement research.