Dimming house lights

[bruce]

I know a few lecture rooms in Uni have got them. It means that all the dimming for the building is in one room. The uni ones have 4 buttons - "All ON" "ALL OFF" and an up and down key which if held increase the brightness or decrease it. They display this as a percentage in a small LCD screen.

 

I've been involved in speccing several installations like this, as part of lecture theatre installations. In general it tends to be a combination of tungsten and dimmable HF flourescents, in several banks. You are usually able to define about 4 different

"scenes", which in a lecture theatre might be

 

all off

all on

and 2 presentation states - screen area dark and appropriate leves of lighting for audience (who need to take notes) and lecturer.

 

There would be a simple "on-off" controller - which effectively selects either scene 1 or 2 - at the doors, and a more sophisticated one which allows selection and modification of the various scenes in the lectern and/or projection box.

 

eg a simple one might be http://www.mem250.com/products/assets/images/HA7012.jpg

 

External control other than the proprietory buttons tends to be analogue or RS232 rather than DMX - although lots of options are available. RS232 is popular if interfacing to AMX/Crestron control systems.

 

I can't remember which system we normally use, but we've certainly used the MEM Studio range (see the HA section in this link) in the past.

 

Bruce.

[Dominicg]

Usually house lights are on a separate fader to the desk however I've seen house lights be controlled on a through one channel on the desk and then once the desk gets switched off you put a control switch box onto one channel to keep them on or override to turn them off.

[Shez]

A theatre I used to work at had upside down dimmers for the house - you faded up in order to dim them down. I think the idea was (back in 10v days) that it would fail safe - if the feed was unplugged / powered down, the house would come up automatically. The mains feed to the dimmer could be switched on & off by whoever & the house would ramp up & down accordingly.

(It was a pain to plot as if you weren't careful, you'd end up with the house randomly coming up for one cue!)