LED Dimmable DMX House Lights System - Page 1
Forum section: electronics / projects

author: paul_g_787
author_rank: Frequent Contributor
timestamp: January 21, 2023, 06:12:39 pm
content: Hi.At the theatre I work at they have decided that they want to replace our "house lights" with LEDs but they want to keep the existing fixtures.The existing fixtures in the main auditorium all use standard Edison screw lamps.The fixtures in the smaller auditorium are all standard BS Bayonet lamps.What we are after is basically change all the lamps to dimmable LED ones, just warm white nothing fancy like RGBWe want to use the existing wiring and replace the old dimmer pack with an LED dimmer pack that is controlled by DMX or can also be set into a "permanently on" mode to be controlled by a manual light switch.Any suggestions as to which system we can use to achieve this? Anyone tackled this already?

author: james_s
author_rank: Super Contributor
timestamp: January 21, 2023, 07:32:24 pm
content: They're just ordinary lamps? Have you tried standard dimmable LED bulbs? Philips and Cree are both brands I've had good luck with. They work reasonably well off of standard dimmers in most cases.

author: drvtech
author_rank: Regular Contributor
timestamp: January 21, 2023, 08:35:29 pm
content: What model are the existing dimmers?

author: bidrohini
author_rank: Regular Contributor
timestamp: January 22, 2023, 08:00:39 am
content: You can check the following bulbs:https://reductionrevolution.com.au/products/philips-led-bulb-e27-edison-screwhttps://www.greenelectricalsupply.com/products/3-watt-led-bayonet-single-contact-base-12v-elevator-light-bulb

author: paul_g_787
author_rank: Frequent Contributor
timestamp: January 22, 2023, 12:01:37 pm
content: Quote from: james_s on January 21, 2023, 07:32:24 pmI was under the impression you had to have special dimmers for LEDs? So dimmable LED lamps will work from a normal tungsten lamp dimmer pack?

author: paul_g_787
author_rank: Frequent Contributor
timestamp: January 22, 2023, 12:03:17 pm
content: Quote from: drvtech on January 21, 2023, 08:35:29 pmThe main auditorium dimmer packs are great big honking strand ones that tale up a whole room. Circa 1960s. Ideally we want to replace these.The smaller auditorium has an early 2000s Zero88 dimmer system I believe. Will have to climb up and have a look.

author: drvtech
author_rank: Regular Contributor
timestamp: January 22, 2023, 12:37:46 pm
content: The main issue with LED House lights is that you really want them to dim right down to zero and not snap off at the bottom. This is close to impossible with dimmable mains LEDs as you still need something to supply power to the control electronics down at the minimum level. There are techniques for doing this but they require some intelligence in the fixtures or the lamps themselves (eg. Offsetting the zero point on the led to be at 10% or so on the supply side)

author: The Soulman
author_rank: Super Contributor
timestamp: January 22, 2023, 12:42:50 pm
content: Quote from: paul_g_787 on January 22, 2023, 12:01:37 pmYeah, no, kinda..At the place where I work we had (have) the same idea to change all house lights to led,we've experimented with all sorts of (mayor) brands and types of replacement led bulbs.We have found the following issues with driving of the shelf bulbs with comom (phase chopper) dimmers:At low levels led is ugly, the color remains the same and only intensity is decreased.Especially when doing slow fade-in and out it is apparent that the led's don't produce any light at the bottom 20% of the range, and will suddenly turn on at fade-in,even worse they won't turn on all at once but each bulb has a different threshold, so expect a disco show when slowly fading in the house lights.I've experimented with driving common (AC) led bulbs with a constant current (DC) led driver, that solved the dimming and turning on/off issues but each bulb would require its own driver..Also ETC came out and showed us theirhttps://www.etcconnect.com/Products/Architectural-Fixtures/ArcLamp/Features.aspxthat was rather nice but it wouldbe fairly expensive, (at around 100 euro's per seat, in total would be looking at 300K for our place..).Our conclusion is to simply minimize use of the dimmable house lights (aprox. 1 hour a day) by installing a second ,led on/off, system that's used when there isn't a audience, during set-up cleaning etc.

author: james_s
author_rank: Super Contributor
timestamp: January 22, 2023, 07:56:28 pm
content: Quote from: paul_g_787 on January 22, 2023, 12:01:37 pmSpecial dimmers do typically offer better performance and work with a wider range of lamps, but most dimmable LED bulbs will work acceptably well on most standard incandescent dimmers. Sometimes there are problems at the lower end of the dimming range and some bulbs are more finicky than others. I've also seen issues where a single bulb would work fine but put multiple LED bulbs on the same dimmer and then things act up. In almost all cases putting a single incandescent bulb, even a low wattage one on the dimmer with the LEDs smooths everything out. A trailing edge dimmer usually works the best but it's not an absolute requirement.

author: Marco
author_rank: Super Contributor
timestamp: January 22, 2023, 09:14:59 pm
content: Quote from: The Soulman on January 22, 2023, 12:42:50 pmThat's of course a result of AC edge dimming and LED lighting electronics, in principle with PWM they can produce any intensity you want though the colour shifting obviously won't work like incandescent.Aren't there any major brand 12V or 24V edison/bayonet LED bulbs? Then use those with DMX or DALI dimmable drivers?

author: james_s
author_rank: Super Contributor
timestamp: January 22, 2023, 09:19:22 pm
content: Philips did make some "warm glow" LED bulbs that color shift. I think they are mostly discontinued now in favor of smart bulbs. If you can find a way to go from DMX to zigbee the Philips Hue white ambiance lamps are dimmable nicely down to a faint glow and the color temperature can be tuned from 2200k to 6500k.

author: dmills
author_rank: Super Contributor
timestamp: January 22, 2023, 09:38:20 pm
content: Quote from: The Soulman on January 22, 2023, 12:42:50 pmThat was my conclusion as well, tungsten looks NICE at down below 20%, LED as a retrofit is a hot mess in the same situation.House lights AND working lights is the way, and the workers (that are what spend most of the time on) can be simple LED or (I last did this some time back) florescent, you want efficiency here. Incidentally, having working lights that do not glare horribly or cast really hard shadow makes the venue far more pleasant to work in.The house lights (Only used when the punters are entering or leaving) are only on for an hour a day but MUST dim right the way down while looking pretty, nothing easily does this better then tungsten, especially as a retrofit to an existing system.

author: themadhippy
author_rank: Super Contributor
timestamp: January 22, 2023, 09:40:23 pm
content: QuoteA few of the zero 88 desk can already talk to Phillips hue lamps,but then again there both owned by the same company.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 22, 2023, 11:55:15 pm
content: Take a look at ESP8266 or ESP32 based smart bulbs, they can be reprogrammed with a firmware that allows for much faster control. Could even make use of "Wifibroadcast" to make the communication stateless and avoid the usual problem of bulbs losing the connection to the AP.https://github.com/Ncerzzk/esp-wifibroadcast

author: james_s
author_rank: Super Contributor
timestamp: January 23, 2023, 12:00:44 am
content: I did that for a while, but then I finally bought a few Hue lamps and realized how much better they are so I gave up on all the WiFi based bulbs. Zigbee is just better for something like that where you have a large number of small devices, it's a mesh network and you don't have to worry about having an IP address for all of your bulbs.

author: ajb
author_rank: Super Contributor
timestamp: January 24, 2023, 09:06:23 pm
content: You may have better luck asking on stage lighting specific communities, purely to increase your chances of finding people with directly relevant experience given the number of variables involved. controlbooth.com is the only active web forum I know of, but there are several facebook groups if you're willing to deal with facebook--Everything Stage Lighting and the aptly named Lighting Designers groups come to mind as pretty active ones.I would think a driverless LED bulb (like those filament style?) might be a better bet, since you won't need to worry about them suddenly cutting on/off at the low end. With a finely-enough-tuned dimming curve you should be able to dim those very deeply, at the expense of 100/120Hz flicker. If you were willing to shell out for a sine wave dimming system that may also help--not necessarily because you need sine wave output, but because those dimming systems will have more flexibility in output shaping and in setting a dimming curve that works well for the bulbs.There are some LED bulbs that dim down to zero, or near enough--I have some such at home, and at the minimum setting of the wall dimmer they are very dim indeed--but may be tricky to find ones that work well for you without a lot of trial and error. A sine wave dimmer that can be configured to chop the leading *and* trailing edges of the sine wave may help with conventional dimmable LED bulbs, as you could set the minimum dimming level to where the pulse length is very short but still above the minimum operating voltage of the driver. Hypothetically that might help with the low end 'snap' on/off and with consistency across bulbs in the same system, but it depends on the details of the driver's dimming implementation.Quote from: james_s on January 23, 2023, 12:00:44 amI'd be very wary of any sort of smart bulb for house lights. Using a consumer device like that for an onstage practical is one thing, but if something goes wrong with the bulbs, or the gateway, or whatever, and all the sudden you can't bring up your houselights that's going to be a big house management issue, and is a potential safety issue if there isn't some sort of accessible backup system (worklights or whatever).

author: Marco
author_rank: Super Contributor
timestamp: January 24, 2023, 10:23:48 pm
content: Quote from: ajb on January 24, 2023, 09:06:23 pmNahh, everything cheap is resistive constant current driver now. Those really don't like dimmers.

author: themadhippy
author_rank: Super Contributor
timestamp: January 24, 2023, 11:08:50 pm
content: QuoteAlsowww.blue-room.org.uk

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 26, 2023, 02:53:00 pm
content: Quote from: james_s on January 23, 2023, 12:00:44 amWifibroadcast is not IP, it's using raw Wifi packets to send the data. The high bandwidth would help if you want individual control of many bulbs at a fast rate.

author: james_s
author_rank: Super Contributor
timestamp: January 26, 2023, 05:54:25 pm
content: Quote from: NiHaoMike on January 26, 2023, 02:53:00 pmThe lamps still need an IP address on the network, at least all of the WiFi bulbs I own do.