Switching LED bulbs from houselights dimmer

[NTABID]

I'm looking for a cheap fix for our community theatre. Stage working lights are currently connected in parallel with house lights (both tungsten) through a stand-alone old fashioned dimmer (in the lighting box at the back of the auditorium). This means that, when using house tabs, stage working lights come on when tabs are shut and house lights on. (I know there are good alternatives to that one, but there are others who think the status quo is desireable...)

 

However, throughout the building we're gradually substituting LED bulbs for domestic tungsten (not there with house lights yet!) Since stage workers are on on most days of the year, there'd be a useful power saving if LEDs could be used.

 

Could one imagine a cheap and cheerful switch for the stage workers activated by the houselight dimmer? Perhaps a relay opened by the difference between mains and dimmer output voltage? Hence, outside performances, when house lights switched off but dimmer on full, stage workers could be controlled as now through existing back-stage domestic switch wired in series.

 

I apologise if this seems a stupid question, but any practical suggestions much appreciated.

 

Sorry if this is seems a dumb question

[timsabre]

Why not just put dimmable LED bulbs in the working lights. The dimming isn't great usually but it would work without modification.

 

I'm not totally sure what you are wanting to do from the above description. How does the "existing back stage domestic switch" come into the setup? What is the relay supposed to do?

[Dave m]

What dimmers?

You can switch some dimmers to just plain "off/on" to switch non dimmable

Ideally you want to have the workers and house lights on different dimmers anyway

[Roderick]

I think you are making this far more complicated than it needs to be.

 

In the community theatre I work with we have a switch that can be operated from stage level and the biobox to turn worklights on & off.

House lights are dimmed separately, we run it through the desk. Worklights are a combination of LED QI and fluoro battens.

Houselights are tungsten PAR38's mainly because there is no economic LED alternative that dims well and has a nice colour temperature.

[NTABID]

Thank you for your replies; I apologize for not phrasing my question clearly enough.

 

Tim - the issue is indeed the compatability of even dimmable LED bulbs with an old dimmer of unknown spec (Electro Control Systems Limelight dimmer, for what it's worth). The key criteria being cost, the specific thought was whether one could cheaply switch LED workers by using a dimmable feed to tungsten house lights (the house lights need to dim, the workers do not). Hence the thought that, as the dimmer output dropped, it could be used to trigger the switching off of the working lights.

 

Of course the setup is far from ideal, but I was merely thinking of a quick short-term fix that maintained the existing link between house lights and workers. If I can persuade others that they really, really don't need this, the solution is very cheap and simple!

[timsabre]

Any led bulb that says it's dimmable should work - the tungsten lamps also on the dimmer will help (sometimes you get strobing / latch on if there are only led lamps on a dimmer).

I would aim for that solution rather than something bodgy with a relay.

[sleah]

Hence the thought that, as the dimmer output dropped, it could be used to trigger the switching off of the working lights.

 

Somewhere inline with the feed to the workers fit a DMX Relay? You'd need to get DMX to the relay plus hard-power (to power the relay board).

[timsabre]

Hence the thought that, as the dimmer output dropped, it could be used to trigger the switching off of the working lights.

 

Somewhere inline with the feed to the workers fit a DMX Relay? You'd need to get DMX to the relay plus hard-power (to power the relay board).

 

I don't think his dimmer is DMX. Sounds like it is a manually controlled 0-10V thing in the lighting box, separate to the actual stage lighting system.

[NTABID]

Hence the thought that, as the dimmer output dropped, it could be used to trigger the switching off of the working lights.

 

Somewhere inline with the feed to the workers fit a DMX Relay? You'd need to get DMX to the relay plus hard-power (to power the relay board).

 

I don't think his dimmer is DMX. Sounds like it is a manually controlled 0-10V thing in the lighting box, separate to the actual stage lighting system.

 

Many thanks for your time and trouble in replying. Will follow Tim's suggestion, if there's any problem with that will use as good reason for separating out the working lights.

Cheers.

[Jivemaster]

Without BUDGET, nothing dims and warms like tungsten. With budget it's possible to dim LEDs nicely, with big budget it's possible to dim and warm LEDs but the rig gets complicated.

 

IIRC there is a post on here about Sydney Opera House switching to LED with lots of care and money, and finding it good.

[david.elsbury]

Jivemaster: yes exactly. But if you re-read they only want workers to be LED so they just need be dimmable so as not to die on the dimmer. ?

[alistermorton]

We don't know the type of fixture used for the workers. If it's a bunch of pendants with ordinary GLS lamps in then the quick fix would indeed be dimmable d0m35t1c style LEDs. If they're R75 style linear lamps in floods it may be a bit harder to find a dimmable replacement, and I know (because, as an experiment, we tried) that just putting those cheap 30W Chinese LED floods on a dimmer is not entirely satisfactory - as expected they flash at the low end, so just swapping out for 50 quid's worth of cheap floods isn't likely to work well.

 

EDIT: punctuation

[sleah]

Hence the thought that, as the dimmer output dropped, it could be used to trigger the switching off of the working lights.

 

Somewhere inline with the feed to the workers fit a DMX Relay? You'd need to get DMX to the relay plus hard-power (to power the relay board).

 

I don't think his dimmer is DMX. Sounds like it is a manually controlled 0-10V thing in the lighting box, separate to the actual stage lighting system.

 

Valid point. Still do-able in theory though with some electronics jiggery-pokery. The relay could even be triggered from dimmed 240v, again - in theory :)

[mac.calder]

If it is an old analogue dimmer that uses 0-10v control, grab a mains relay which is triggered by 12v - these tend to have an operating voltage of between 9 and 13v. There are also voltage monitoring relays where you can set the closing voltage to anywhere between a given range - so you could set it so that at 75%, workers go off.

[timsabre]

If it is an old analogue dimmer that uses 0-10v control, grab a mains relay which is triggered by 12v - these tend to have an operating voltage of between 9 and 13v. There are also voltage monitoring relays where you can set the closing voltage to anywhere between a given range - so you could set it so that at 75%, workers go off.

 

There's no way a 0-10V control signal would drive a relay coil. You'd just kill the controller output (probably destructively). A voltage monitoring relay might work, but really, this would be just making a strange setup even more strange.