Variable colour temperature LED bulbs - Page 1
Forum section: electronics / projects

author: Rachie5272
author_rank: Regular Contributor
timestamp: January 05, 2016, 10:04:04 pm
content: I keep looking for these every now and then, but I have yet to spot them. Does anyone make variable colour temperature LED bulbs? Specifically, ones which change colour based on a dimmer switch. I know full RGB bulbs exist, but they only work with atrocious user interfaces. There's no way I'm going to carry a smartphone around to operate a light when there's a dedicated switch mounted conveniently on the wall.

author: Fungus
author_rank: Super Contributor
timestamp: January 05, 2016, 10:30:44 pm
content: Stick a small Arduino inside the switch, make the interface whatever you want!

author: ajb
author_rank: Super Contributor
timestamp: January 05, 2016, 10:35:33 pm
content: I've seen bulbs that shift color as they dim, to mimic the redshift of incandescent bulbs. I want to say they were made by Philips, and I saw them at Home Depot, but could be wrong. Is that what you want, or do you want the ability to change color temp independent of brightness?

author: rdl
author_rank: Super Contributor
timestamp: January 05, 2016, 10:38:55 pm
content: What I'd like is for the bulb to be self-contained with a micro and RTC, then have the bulb auto adjust color based on the time of day/day of year. Warm for nights and evenings with gradual change to cool white during the day. Probably not gonna happen though.

author: kmm
author_rank: Regular Contributor
timestamp: January 05, 2016, 10:59:59 pm
content: Quote from: Rachie5272 on January 05, 2016, 10:04:04 pmI have an RGBW strip on a beam in my living room being controlled by one of these "Magic UFO" wifi modules. It works reasonably well for basic RGB+W (they can be controlled independently, so color temp is more or less arbitrarily controllable) color control, but the "effects" it has are the usual low-effort and irritating crap found on most consumer grade LED controllers.The protocol is very simple (stream a few command bytes to a TCP port) and has been reverse engineered, but there appears to be some variance as mine doesn't respond to the sample packets I sent it. I may also have been making the packets wrong in some trivial way, I've only spent an hour or two poking at it.I intend to eventually packet dump it to see how it differs from what I've seen published, but this requires rooting my phone and I'm just not looking forward to that so I've been putting it off.It appears to be based on a modernized 8051 micro, and one of the ESP8266 integrated wifi stacks, so there's likely a lot of hackability to these things. Not sure how deep you want to go, but I don't see why it wouldn't be fairly easy to rig a dimmer switch with a similar ESP8266 module that emits command packets for a device like this.http://www.amazon.com/LEDENET%C2%AE-Controller-Android-Smartphone-Control/dp/B00MDKOSN0Not sure if there are any bulb-format devices based on similar hardware and protocols, but it may be worth looking around. Other option is to put one of these modules in the base of a lamp and install a low-voltage RGBW emitter in place of the bulb; may not be advisable to hack your antique Tiffany lamps though.There's tons of off the shelf stuff that's cheap and hackable or usable as raw material though, so this is definitely a solvable problem with reasonable effort.

author: Rachie5272
author_rank: Regular Contributor
timestamp: January 05, 2016, 11:51:37 pm
content: Quote from: ajb on January 05, 2016, 10:35:33 pmThis is exactly what I want. Is the effect pronounced though? Say, shifting from 5500 K to 2500 K?Quote from: rdl on January 05, 2016, 10:38:55 pmI'd like this even better. The reason I want this is to help regulate my sleep cycle. Blue light suppresses melatonin production, which is great during the day, but terrible at night. I want my lights to be bright and blueish during the day, but dim and yellowish at night. For lack of a RTC, I can simply adjust the dimmer switch.I've seen RGBW strip lights, but they simply aren't bright enough for general room illumination. I expect bulbs to be at least 800 Lumens each, or else I consider them to be novelty indicator lights.