# Cue Light System: What do you think?



## Lambda (Nov 13, 2011)

Well, some people have been asking me about a cue light system for a while. So I've planned one out. 
We currently have a three-wire cord running from the control booth to stage-right wing, so I thought I'd just use this instead of pulling new cable. I can control four lights this way. 
For the base station, I was thinking a simple interface with silent rocker switches (not momentary) for each light, and an indicator wired in series that will warn of a broken circuit. 
The light units themselves is where I have some doubt, I think I'm over-thinking them. They'd be small boxes with large LEDs in them, that would connect to the line with some sort of robust three-pin plug. There would be two of these per unit, allowing them to be daisy-chained in parallel like DMX devices. Each unit would have switches allowing its "address" to be set.

Questions I have: 
What type of connector should I use for the light units? I don't want to use XLR, since the working voltage will be 6 volts AC at times, I'd hate for someone to accidentally connect it to some audio equipment. I don't want to use telephone or cat5 because they cables should have the ability to be connected end-to-end like XLR cable can.

Do you think I'm over-thinking the light units, what with the addressing and all? Would it be better just to give up some versatility and have each unit hardwired to be a certain number?

Do you think I'm under-thinking the light units, should I have a brightness control for the LED? 

Is there anything drastically wrong that I'm overlooking here?

And overall, what do you think of it? Is it worth building?


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## chausman (Nov 13, 2011)

I'f there is three wires, shouldn't that only be able to control one light?


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## Lambda (Nov 13, 2011)

chausman said:


> I'f there is three wires, shouldn't that only be able to control one light?


 
No. An LED will only light when current is applied in correct polarity. So if you have one 'hot' wire and a ground, with two LEDs connected between the hot and ground with polarity opposite, if you apply a positive voltage, one lights. Apply a negative voltage, the other lights. Apply an alternating current, and they both appear to be lit at the same time (although in reality they flicker). 
I'm using half-wave rectified AC for each LED. When both the lights on one wire are switched on, the result is a sine wave and they both light. 
So, with two LED's per wire and one ground, three wires can control 4 lights, and they can all be on at the same time if needed. 
Once you have the ground wire, each additional control wire can control two additional LEDs.


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## Chris15 (Nov 13, 2011)

Yes I think you're over thinking it all 

Use XLR, it's just easier...

How are you planning this control regime to work?
Are you planning 1 common and 2 wires of half wave switched AC?

So you answered my question while I was posting...
You realise you can switch other loads that way using relays, just by throwing a diode in between the control line and relay? (in one direction for one, the reverse direction for the other)


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## Lambda (Nov 13, 2011)

Chris15 said:


> Yes I think you're over thinking it all
> 
> Use XLR, it's just easier...
> 
> ...


 
Yes, half-wave switched AC. About the XLR, you don't think that someone might conect the system to a mic-level input? That's my main concern here, inexperienced high-school students will be using this. And what _really_ concerns me is that one of the current freshmen will be in charge of sound in 4 years.

EDIT: 

Chris15 said:


> You realise you can switch other loads that way using relays, just by throwing a diode in between the control line and relay? (in one direction for one, the reverse direction for the other)


Hadn't occurred to me, I've never needed to do that. I'll remember that though.


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## Chris15 (Nov 13, 2011)

Use an XLR4 or XLR6 or XLR7 - they are all far less frequently encountered.
It does mean you'll need dedicated cables though.

That said, we've been running comms on 3 pin alongside audio for years and that's 30V DC.
The incidents are in my experience rare...


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## derekleffew (Nov 13, 2011)

Lambda said:


> ...What type of connector should I use for the light units? I don't want to use XLR, since the working voltage will be 6 volts AC at times, I'd hate for someone to accidentally connect it to some audio equipment. I don't want to use telephone or cat5 because they cables should have the ability to be connected end-to-end like XLR cable can. ...


All valid points. I'm guessing your criteria also include: small, fairly readily available, inexpensive but sturdy, easy to terminate, rarely found for any other purpose, both genders in both line and panel mount. 
XLR4 meets many, but not all, of those. Likewise, NEMA ML-2. Or one of the bajillion offerings from Molex or Cinch-Jones. Do you have a Fry's Electronics or equivalent nearby (just wander the aisles), or are you limited to The Shack and mail-order?

Against your objections, I think I'd still use XLR3, but LABEL VERY CLEARLY, paint a unique color, keep the parts locked up when not in use, etc.

Have you seen these threads?
http://www.controlbooth.com/forums/stage-management-facility-operations/2996-cue-lights.html
http://www.controlbooth.com/forums/stage-management-facility-operations/6740-led-cue-light.html
http://www.controlbooth.com/forums/lighting-electrics/25808-cue-light-systems.html
http://www.controlbooth.com/forums/...26484-cue-light-system-what-do-you-think.html
There *may* be un-mined gold in them thar threads; then again may only be pyrite. Mama always says, _"ControlBooth is like a box of chock-lats; you never know what you're gonna git."_


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## tyler.martin (Nov 13, 2011)

I was going to mention Cinch-Jones connectors. I used a bunch from old Slide Projector pickle cables for a stage marker LED system.


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## Lambda (Nov 13, 2011)

derekleffew said:


> All valid points. I'm guessing your criteria also include: small, fairly readily available, inexpensive but sturdy, easy to terminate, rarely found for any other purpose, both genders in both line and panel mount.
> XLR4 meets many, but not all, of those. Likewise, NEMA ML-2. Or one of the bajillion offerings from Molex or Cinch-Jones. Do you have a Fry's Electronics or equivalent nearby (just wander the aisles), or are you limited to The Shack and mail-order?
> 
> Against your objections, I think I'd still use XLR3, but LABEL VERY CLEARLY, paint a unique color, keep the parts locked up when not in use, etc....



I think the ML-2 is really overkill for 6 volts and a handful of miliamps. I've looked through Molex and cinch-jones, but didn't find what I really had in mind. 
This is what I had in mind. But I can't seem to find an in-line jack or panel-mount male connector for it. 

I don't really have an electronics store nearby, I'm limited to mail-order (or radioshack, but their stuff is too expensive unless I really need it _today_). 
XLR3 does seem to be the best choice, but believe me, as soon as I leave next year, despite any labeling or painting, people will still be grabbing for them when mic cable is scarce. Or they'll be using mic cable for the cue lights when it's handy.
I suppose the chance of things going wrong is small, but I keep invisioning somebody connecting the cue light system directly to a power amp, and the horrid KBZZZZZZZ- followed shortly by the stench of burnt electronics.
4-pin XLR might still be an option. I'll have one unused pin, though. It's also the same cable as we use in our intercom, which is used much less frequently than XLR3, so less chance of someone connecting it where it shouldn't be.


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## Lambda (Nov 13, 2011)

tyler.martin said:


> I was going to mention Cinch-Jones connectors. I used a bunch from old Slide Projector pickle cables for a stage marker LED system.


 
Oops, I missed your post. What do you mean by a slide projector pickle cable? I haven't heard that term.


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## derekleffew (Nov 13, 2011)

*tyler.martin* inspired me, as I thought the Kodak pickle was a 5pin DIN, but different than MIDI. 

Lambda, What about a 3 or 4pin DIN?


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## emac (Nov 13, 2011)

Is there anyway to post pictures and schematics when you are done???? I have been trying to get something like this together for a long time and that would help me a ton.


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## Chris15 (Nov 13, 2011)

I've always thought of DIN as a "back of the rack" connector rather than an on the deck connector.
They rapidly pale in comparison to an XLR in terms of ability to be dropped, stepped on, etc. and survive...


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## shiben (Nov 14, 2011)

Lambda said:


> I think the ML-2 is really overkill for 6 volts and a handful of miliamps. I've looked through Molex and cinch-jones, but didn't find what I really had in mind.
> This is what I had in mind. But I can't seem to find an in-line jack or panel-mount male connector for it.
> 
> I don't really have an electronics store nearby, I'm limited to mail-order (or radioshack, but their stuff is too expensive unless I really need it _today_).
> ...


 
I am confused why you cant just use an XLR cable for this project in the first place. I used to have a huge bunch of projector dousers that you hooked up to a 9V battery and switchbox via an XLR/mic cable, and Comms uses them all the time with way more voltage than you will be. Wouldnt the only thing you need to label well be the outlet where you hook your cue lights to? I guess Im just wondering why you cant use mic cables. If they run out of them, you clearly have a problem anyhow, right? Saves you from having to buy too much new stuff as well.


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## Lambda (Nov 14, 2011)

emac said:


> Is there anyway to post pictures and schematics when you are done???? I have been trying to get something like this together for a long time and that would help me a ton.


I will post final schematics if it ever gets built. There's a chance it won't get approved by the department, and if it does, it will likely take a while.


shiben said:


> I am confused why you cant just use an XLR cable for this project in the first place. I used to have a huge bunch of projector dousers that you hooked up to a 9V battery and switchbox via an XLR/mic cable, and Comms uses them all the time with way more voltage than you will be. Wouldnt the only thing you need to label well be the outlet where you hook your cue lights to? I guess Im just wondering why you cant use mic cables. If they run out of them, you clearly have a problem anyhow, right? Saves you from having to buy too much new stuff as well.



I suppose in the end I will go with XLR3. The DIN connectors, though they will work, seem to be less durable and they don't lock. I am concerned with longevity of the system, because after I leave it will likely be a long time before someone comes along who cares to maintain it. 
We _have_ had problems in the past with mic cable shortages, until it was discovered that there were a great many of them running under the stage dating back to who-knows-when. Even now, we have problems with intercom cable (XLR4) shortages. Every proposal I submit for new cable seems to be ignored...


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## hsaunier (Nov 15, 2011)

Might be a little overkill, but nuetric makes a "PowerCon" connector that I have seen used to connect stringers for stage power. The connecter is the same principle as the standard NL4 speakon but has a different stud pattern so they will not interconnect.


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## Chris15 (Nov 15, 2011)

Using Powercon would be a really dumb idea.
It nigh guarantees that at some point, the box is going to get mains put across it.
That will not end well
Don't do it. EVER.

Powercon is for mains power and mains power only.

btw, neither Powercon nor Speakon would meet the request for a connector that can be extended in line...


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## Traitor800 (Nov 15, 2011)

Chris15 said:


> btw, neither Powercon nor Speakon would meet the request for a connector that can be extended in line...


 
Neutrik makes both male and female genders of both panel mount and inline speakon connectors, so it could be a viable option for this project. One thing to keep in mind is the speakon genders are not as obvious as some other connectors. In a typical audio system the panel mount is considered male connector and the inline is considered the female.


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## hsaunier (Nov 15, 2011)

Well there you have it.


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## Chris15 (Nov 15, 2011)

Erm, There is no NL4MX.
Yes, there is the NLT4MX. It's from the 40A rated metal bodied family and that series is somewhat more pricey than the NL series.
Of course there are Chinese males abundant, generally of typical Chinese quality though.

I'd have thought we still had a risk at this point of getting a far greater voltage across the cue light system than it's designed for. A decent amplifer can easily dump north of 100 volts across it's load... (Without me doing any impedance or voltage sums - it's late.)


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## Traitor800 (Nov 15, 2011)

Chris15 said:


> Erm, There is no NL4MX.
> Yes, there is the NLT4MX. It's from the 40A rated metal bodied family and that series is somewhat more pricey than the NL series.
> Of course there are Chinese males abundant, generally of typical Chinese quality though.
> 
> I'd have thought we still had a risk at this point of getting a far greater voltage across the cue light system than it's designed for. A decent amplifer can easily dump north of 100 volts across it's load... (Without me doing any impedance or voltage sums - it's late.)


 
Last time I checked the STX Series (to which the NLT4MX belongs) of connectors were still part of the Speakon family. And while yes they are more expensive than the other Speakon connectors, you don't have to purchase a barrel coupler to extend your cable which helps to offset the added cost of the connector.

And I would put a Female Panel mount Speakon (opposite gender as what is used on most speakers and amps) backstage for the cue light system to help prevent people from plugging amps/speakers into the cue light system.


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## tyler.martin (Nov 11, 2012)

Maybe time for some thread resurrection...

Did you ever build your system? 

I need to replace our homebrew system. Currently it uses a control box in the booth connected to the PSU onstage with HD15 Monitor cable. A pin provides the common 12v DC power to the switches at the SM desk, and when the switches are on, they trigger a 120v relay. All of our baskets are regular 120v lamps, but the relays are only rated for 1 Amp at 120V. I was thinking about rebuilding it to a similar system but replace all the HD15 with 2 runs of CAT5. I do need to be able to control 8 separate cue lights. 

Or my other thought is to build a new one that uses large LED's in project boxes and use CAT5 as the wiring. We operate on the Standby - On - Go - Off principle, so only one light is needed per station, but it would be great to be able to daisy chain the boxes.


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## Chris15 (Nov 11, 2012)

If you changed your 12V DC supply to be an 12V AC one, you could effectively double your number of control channels for a given number of wires.

I may have posted this before, but refer to the attached diagram...


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## Lambda (Nov 12, 2012)

tyler.martin said:


> Maybe time for some thread resurrection...
> 
> Did you ever build your system?
> 
> ...



I had thought this thread was dead and buried. No, I never built the system, it did not get approved by the department (and at this point I'm no longer even affiliated with that facility).
With my design you'll be able to use the LEDs and cat5 and daisy-chain the boxes like you describe, just fine. I'll see if I can dig up my old diagrams and scan them in for you (or just draw up some new ones), but it might take a while. Chris is right, if you use switched half-wave AC instead of DC you'll be able to control more lights with less wires.


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## Dreadpoet (Nov 12, 2012)

I really like gam's cue light....takes all this hassle of cue lighting away for relatively inexpense


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## tyler.martin (Nov 12, 2012)

Dreadpoet said:


> I really like gam's cue light....takes all this hassle of cue lighting away for relatively inexpense



Unfortunatly it really doesnt work for our needs. I dont need 4 colors of LED, and I need them to be controlled per station.


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