LED Cue-light

[Charc]

So I could probably just figure this out tomorrow, but I thought this would be an interesting topic for the booth, and has some educational merit.

So today I was running XLR (20 minutes before the house opened!) with the ME for a newly home-brewed cue-light system. It was pretty interesting. A little DC power supply into a hobby box, with unknown electronics/wiring inside, two toggle switches and two XLR outs. The XLR was run from the hobby box to the cue-light location, and a small adapter was attached to the end of the run, also home-brew. He took a bare connector, and wired it up with the LED sticking out the hole where the cable would be...

Looked like a pretty nice little setup, and cheap/easy considering most theaters should have the parts on-hand.

How would you go about setting up this system? What would you do differently than described? How would you wire in the LEDs, any resistors, or anything else relating to the project?

[derekleffew]

I'd use this: TMB's ProCue.

[gafftapegreenia]

Yea, and ProCue costs how much? We all know how Charc's school loves to spend.


Side note: TMB just gets to make all the fun widgets don't they?

[derekleffew]

Originally Posted by gafftapegreenia

...We all know how Charc's school loves to spend. ...

Stay with the program, Greenia. This is for Charc's internship at the professional theatre, and we all know that LORT theatres have virtually unlimited budgets.

Originally Posted by gafftapegreenia

...Side note: TMB just gets to make all the fun widgets don't they?

Yes, whatever did we do before TMB and City Theatrical? I'll tell you--we made things ourselves, with varying levels of success and, in the long run, often more costly.

[gafftapegreenia]

I guess I'm slipping, Derek. I guess I'll have to start both reading the board constantly AND start taking notes on everyone's life.

But what about the feeling of accomplishment that comes with making your own gear, or, I mean, the smashing your head into a wall when it fails?

[Footer]

Originally Posted by gafftapegreenia

I guess I'm slipping, Derek. I guess I'll have to start both reading the board constantly AND start taking notes on everyone's life.
But what about the feeling of accomplishment that comes with making your own gear, or, I mean, the smashing your head into a wall when it fails?

Or dealing with the SM who is smashing your head into the wall when it fails, thats usually how it goes.

[cutlunch]

OK I'll try and answer Charcoal's question before we forget it.

What you saw is fairly simple to build. It's a project you could easily handle.

First here is a quick link about wiring LED's.

http://white-leds.co.uk/led-wiring-guide.htm

Just remember different LED's have a different forward voltage. You normally find it listed in the suppliers catalouge.

You forgot to mention whether the LED was just one colour and how they used the cuing system. Ie Did they only turn the LED on just before the cue then off at cue time? If it was this is the simplest thing of all to make. You have your battery supply so you wire battery negative to one pin of the XLR in your control box. The battery positve is then wired to one side of a switch. From the other side of the switch you could use the resistor you need to connect the switch to another pin on the XLR . Then in the XLR plug for the other end you just wire the LED across the same two pins. That's all there is to it. To improve the LED end you put expoxy resin to fill the XLR cap to hold the LED in.

For a two location system like your LD's one just duplicate the above you can use the same battery supply. Note for battery you can also use a DC adaptor. I would use at least a 9V source.

For working out the value of the current limiting resistor I would set the current value higher then you need by 10 or 15 Milli Amps this will allow for the resistance of the cable.

Charcoal would you like to hear about a slightly more complicated unit that uses a two colour LED?

[David Ashton]

I made one about 30 years ago when leds were new technology, in the control box is a 3 volt transformer connecting to 2 switches, one switch connects to the anode of a green led and the other to the cathode of a red led.
then join the green cathode and red anode together to one wire and the other side of the transformer to the other wire on the 3v transformer.
At the other end of your 2 core cable a box with a red diode cathode and the green diode anode joined together to the "live" 3v wire and the other ends to the common wire
Basically the two green leds are in series on the positive half of the waveform and the two reds on the negative.
Very safe and very cheap.

[avkid]

You need a three position switch.

[cutlunch]

Your diagram doesn't quite work but I think you have the idea but I'll go over it again to make sure.

We'll pick pin 1 to carry the common battery gnd (-)

The battery positive is connected through a suitable resitor to a two postion switch with centre off. Connect the battery to the common input of the switch.

Ie the one that if you put one leg of continuity meter on this switch contact leg and the other leg of the meter on either of the other switch contacts when you move the switch to the on positions you get a circuit made without having to move the lead off the common. Most of the time this is the centre connection.

Now you have detrmined the switch connections wire one side of the switch to pin 2 and the other to pin 3 of the XLR.

At the other end join the cathodes of both LED's together and wire to pin 1. Wire pin 3 to the anode of the RED led and pin 2 to the anode of the GREEN led.

To work it move the switch from the centre off position to one side then another making sure the Led's light in turn.

Try diagramming that but use three wires on your diagram.