Control/Dimming Opto Isolator

LEX Products makes a one in two out that's proven useful. I don't recall the cost............
 
Do you need an opto-splitter (ie, are you trying to provide equipment protection against electrical faults on the data lines, or solve a ground loop issue), or do you just need a booster?

As far as DIY. . .

If it's the latter, a pair of RS485 transceivers (two MAX485 equiv, or one MAX488 equiv) 'back to back' with a 5V power supply will be all you need. Easy peasy. But this provides no actual isolation, so it's only useful if all you need is a signal boost and you are not facing objectionable voltages.

If you need isolation to address ground potential differences, then you might use one or two isolated transceivers like the MAX1480. This is a complete, fully isolated transceiver in a single package, so it's only a bit more complicated than its non-isolating cousins, and provides protection up to 1600Vrms. However, special care must be taken to not undermine that protection when you construct the circuit. If you really need isolation/protection, your safest bet is to buy something off the shelf.
 
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unfortunatly, i have found out how poorly our building was wired. I have mentioned it in a previous thread, but I have 10 Male DMX "inputs" through out my theatre. Thursday afternoon we finally figured out how they were wired. They are all just daisy chained together. we figure the run is probably close to 300ft, terminating at my dimmer rack. So now that I know they are all one big unhappy circuit, I would like to use them as outputs, but i think it would be logical to protect my console and gear from any funny business.

So I would like a full opto isolator, with no splitting neccessary. However, the Dsplit looks the most reasonable and cost effective (Its hard trying to get a P/O for a $400 box that "makes more wires come out then in" (president of our board :( )
 
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If you want to use all of those connectors you're going to need more than just an optosplitter at the console. You're going to need a repeater at each and every plug.

DMX is meant to be a linear multidrop network, meaning that it should be cabled from one device to the next to the next with no splits or branches and no stubs any longer than absolutely necessary. From what you've described, all of those male DMX connectors being daisy chained comprises a linear multipoint topology. But if you start adding cable and receiving devices to those connectors, you're going to turn it into a branched network, which means an impedance mismatch (source of signal reflections) at every split and excessive loading on the driver (console) even if you don't have more than the standard 32 devices on the network.

You can get around this by placing a repeater on each of those connectors because the repeater is just another receiving device as far as the backbone of the network is concerned, but will repeat all data from that backbone onto its output which is, electrically, the head end of an entirely separate DMX network. The repeaters need not be optoisolating for this purpose, since you're unlike to get ground potential differences of any significance, but you can opt for optos if you want the protection they provide.



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The other option is to split the DMX line at each of the existing male connectors so you have a female on the side towards the board and a male on the other side. When you need to use one of those points, hook whatever devices in between the two connectors; otherwise just keep the male and female mated so that you can use downstream ports. However with this method, you're limited to 32 devices total sicne it's all one single network. Whereas with a repeater on each connector you can have up to 32 devices per each output.
 
for a short term solution, you could pick up a Chauvet DMX splitter. It has 2 outs. I picked one up on close out for about $60.
 
If you want to use all of those connectors you're going to need more than just an optosplitter at the console. You're going to need a repeater at each and every plug.

That was the plan... I am looking to buy maybe 3 total, so I can leave one up on my catwalks for the scrollers, and have the other 2 float around to the other ports for movers and or atmospheric effects
 
That was the plan... I am looking to buy maybe 3 total, so I can leave one up on my catwalks for the scrollers, and have the other 2 float around to the other ports for movers and or atmospheric effects

Ah great! My impression was that you were just going to put one at the console, but I'm glad to hear you laready have the right idea.
 
You may want to consider getting a 3 or 4 way opto-spiltter, and set up some sort of patch panel solution, instead of having things "float around".
 

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