Show Relay Mute

[TomHoward]

Has anyone got a clever way of muting the show relay during intervals & at the beginning and end of shows?

 

I could easily put a mute switch in by the control position but I'm certain it'll either get left open (rendering it useless) or more likely will get left closed at the top of shows.

 

The problem we have is the foyer could do with muting during pre-show and interval and it sometimes gets left on during the day during show runs, which transmits any libellous or personal conversations in the space through the whole building.

 

I'm expecting it's a silly question and the answer is "don't forget to switch it" but just thought I'd ask in case anyone had found something inventive to tie it to.

[henny]

How about a relay on your house lights when they on you wouldent be in show mode but off you either got an empty building or a show

[boatman]

Has anyone got a clever way of muting the show relay during intervals & at the beginning and end of shows?

 

I could easily put a mute switch in by the control position but I'm certain it'll either get left open (rendering it useless) or more likely will get left closed at the top of shows.

 

The problem we have is the foyer could do with muting during pre-show and interval and it sometimes gets left on during the day during show runs, which transmits any libellous or personal conversations in the space through the whole building.

 

I'm expecting it's a silly question and the answer is "don't forget to switch it" but just thought I'd ask in case anyone had found something inventive to tie it to.

 

A muting relay with its coil connected to the house lights would do the trick. You'll also need a bypass switch so that you can have the show relay on when the house lights are up if required.

[J Pearce]

A big red light at SM desk that lights when show relay is on tends to focus the mind.

[TomHoward]

House lights are a good idea.

 

Unfortunately we often don't run with an SM desk - we just run with ops who follow a script, so they can miss auxiliary things like the show relay mute.

 

Re the bypass switch for when we need it, we have a zone mixer than has separate inputs for switched show relay and solid show relay - so we can select by zone whether they are running from switched or solid. An input switched from the house lights sounds like it would work well - as the audio racks get turned off at the end of the day.

 

The only problem is our house lights are dimmed and we tend to run them at about 50% - is it possible to run a 240V relay from 50% dimmed power (it's not quick enough for it to chatter is it?) or do I really need to install a DMX relay running from one of the house light DMX channels?

[GridGirl]

In my last theatre our show relay simply had a mute switch in the control room. Casts soon got very good at coming to find us if we'd forgotten to switch it on - but you need to have easy access from backstage to either the booth or someone on coms for that to work.

[boatman]

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The only problem is our house lights are dimmed and we tend to run them at about 50% - is it possible to run a 240V relay from 50% dimmed power (it's not quick enough for it to chatter is it?) or do I really need to install a DMX relay running from one of the house light DMX channels?

 

Hang a 240V/24V transformer across the house lights and use a simple bridge rectifier, reservoir capacitor, 12V regulator and a 12V relay. That should work OK down to about 30% and drop out when you take the house lights right down.

[alistermorton]

We use a DMX relay to control whether the video for the show goes to the foyer and other rooms or the rolling adverts get shown. This switches over at a preset level - below 30% it's one way, over 30% it's another (actually, it's a 4-way switch but the principle applies). You could use something like that to switch the audio, so normally it's off or piped music or whatever, and only goes over to show relay when the lighting board tells it too (or when the house light DMX level is below a certain point). We have a channel on the lighting board dedicated to show relay control, so when the cue to dim the house lights runs we change the switch over, and the reverse when the lights come back up again. It does mean that the lighting programmer has to remember to put the relevant level change into the right cues, but it does mean that nobody on stage has to remember each night to flip a switch, it's just part of the show program.

 

The switch in question is one of Milford instruments products IIRC.

[DrV]

How about using a relay to do the mute and running it from ordinary 2 way light switches or intermediate switches if you want more than 2 controls. That way anyone at any position can turn it on or off

Dave

[dbuckley]

In our bijou theatre, the dressing room is behind the stage, with doors leading directly onto it at each side, and when the doors are shut its hard to hear on-stage action, so there is a stage relay going in, and there are microswitches about to be fitted to the doors to mute the stage relay when the doors are open.

 

Several other functions are being controlled by a PLC, with buttons with LEDs on them, such as smoke detector override. The advantage of the PLC is that it also controls the power contactors, based on security alarm armed or not, so it can undo things like the overridden smoke detectors on alarm set, not when the timer expires some time later.

[TomHoward]

I've had a think about this and there are three states where show relay ought to be muted:

 

House lights are on (easy)

Workers are on (easy)

Blinds were last driven in the 'up' direction (which is okay but I need a flip-flop circuit).

 

I'll then knock up a three-way box with relays for house lights, workers, and a flip-flop that closes when blinds are driven UP, and clears when the DOWN button is pressed.

This should cover all eventualities - either we're in a house or audience state, we're working with the workers on, or we're working with the workers off but the blinds up - we have big windows so actually most days we don't even turn the workers on.

 

The only bit that isn't completely obvious is the flip-flop bit - and then I'll make a little indicator with 3 LEDS / neons to indicate which route it is muted by for fault finding.

 

 

 

All three of these are 240V control - house lights are dimmed 240V, workers are hard 240V and blinds are 240V up/down momentary switches which drive contactors - so that just needs a circuit that holds state on 'up' pressed and clears on 'down'.

[TomHoward]

I'm drawing a bit of a blank as to how to do the two-way blind control neatly - basically what we've got is a two-way momentary switch which is held one way or the other to drive the blinds up or down - 240VAC common in the middle, and drives 240V to two rails for up and down.

 

I need to hold a relay to whichever of the two rails was last energised - to give an approximation as to whether the blinds are up or down.

(Really I only need SPST output - closed and latched when the up rail is energised, and held until the down rail is energised.)

 

I reckon I can do this using a relay holding itself via it's own coil, and raising the second side of the coil to clear it, but it needs to remain energised (possibly for days on end), which I'm not happy with - impulse relays hold without power, but the ones I've found change state based on a single coil being energised - what I really need is a dual-coil unsprung relay - so a coil needed to drive each way and it remains in that state without holding power.

 

Does such a thing exist and I just haven't found it?

 

Oh - it also should really be continuous rated - some of the impulse relays are only rated for a few seconds being energised - the switches could in theory be held continuously but in practice it takes around 40 seconds to drive the blinds up or down - so would regularly being energised for that time.

[boatman]

A bit of lateral thinking. Could you add a limit switch to one of the blinds? Either to detect when it's "Fully Open" or "Not Fully Closed". The choice obviously depends on whether you do either of those things with your blinds. If you only operate them between some half-open & half-closed states then it ai'nt gonna work.

 

Edit: to remove unnecessary quote.

[Glyn Edwards]

Do you have an upper limit switch for the blinds? Could you interface a flip flop circuit to that which then drives an impulse coiled relay?

 

Boatman and I think alike at the same time

[TomHoward]

The blinds are usually always fully closed during show state - but they are not always opened fully - often during runs we only open the bottom 12 inches - so the mute could be connected to the bottom limit switch - so un-muted when the bottom limit is engaged - and muted otherwise.

 

However the only problem is that this wouldn't allow us to over-ride the mute - as I had been thinking about if we wanted to un-mute with the blinds open we could just momentarily push the 'down' switch - in the rare occasions we do run shows with the blinds open.

 

Also the cabling for the limit switch would be a pain - the limit switches are on the blinds themselves and the blinds are fed from spurs - so no conduit runs directly to the blinds. All the other circuits are available in conduit in voids and lofts so wouldn't need any decoration work to install - so although it's possible driving from the rails would be an easier way to do it if possible - and it would allow the over-ride/workaround and basically we could 'nudge' them in the opposed direction from either end setting to over-ride either way.