paulears Posted March 19, 2012 Share Posted March 19, 2012 Joshva - the resistor is fine. The subs was just an example showing how a formula is pretty useful for things other too. I don't know much of Sri Lanka but you have managed to get lighting equipment in reasonable quantity, yet can't get access to basic thing like cable? Can you not buy from other countries direct - I tried a few of the big firms who seem able to deliver to your country? It does sound like the lighting industry in your country is pretty undeveloped if the people who supply kit don't understand the basics. I'd also suggest having a look at the basic electrical calculations again - because if you have a computer, you have a calculator and typing in a few dumpers and multiplying and dividing really isn't heavy maths. Watts is E (E is voltage) squared R. so %V squared is 25, and 25/120 gives 0.20W 5volts squared =25V 25 divided by the resistance (120 ohms) give you .2 - which is less than a quarter of a Watt - hence why your half Watt resistor is fine. Plenty of people are trying to help, but you seem very very negative all the time. Every time you say no no, we say yes yes - when you seem to just give up and want something even easier. Look at the fuss about the XLRs even if your XLRs didn't have numbers (which they all do), the picture shows which pin is which? You could just make up your cable to look exactly the same as the one in the picture - it will be fine. The colour of the other two conductors don't matter because as long as they are wired to the same pin each end - the outer one, or the middle one with respect to the ground one, on every cable you make, it will work. Best guess is that your 20 items in a single run will be fine, with the terminator at the end - which goes to the pins that are NOT ground, labelled 1. However - it would have been easy to do a little bit of research first, then you wouldn't have had to show everyone your weaknesses. We don't really mind, but before I posted that I couldn't do the basic maths, or didn't know how to find the right pins, I think I'd have found out myself rather than have posted all this. It's perhaps just that as a mainly UK forum, we're a little unused to the problems people in shall we say less developed countries have - not your fault if your industry is not really quite with it, but we are having real trouble answering your questions in a way you understand without offending you. I've been looking at some typical Sri Lankan electrical installations on the net, and the idea of using proper plugs seems to have not quite been understood either. Our group opinion is that you should just go for it. Likely issues will be to do with soldering - are you any good? Dry joints, stray wires, poor tinning are going to be much more of a danger than the cable type I suspect. Link to comment Share on other sites More sharing options...
plainman007 Posted March 19, 2012 Author Share Posted March 19, 2012 Hi Tim, Run them on the ground meaning ? Sorry im not asking rhetorically, but sincerely to understand what you meant. Im running this mostly on the floor only. Except for at the wings, I dont want people stamping on them so im raising it above 10 ft and then the cable desends again ner the back drop and goes on the floor and up the truss to each and every moving head. Thanks Link to comment Share on other sites More sharing options...
timsabre Posted March 19, 2012 Share Posted March 19, 2012 I just meant, rather than installing all the cable and then finding you have problems, test out the full length you're going to use before you install the cabling. Link to comment Share on other sites More sharing options...
pritch Posted March 19, 2012 Share Posted March 19, 2012 One thing worthy of note is that DMX cable doesn't have to have 'DMX' stamped on it; a lot of cables with the correct electrical characteristics will do just fine - I guess part of the issue that might come up though is how handleable the stuff is (how nicely it coils, how it copes with the rigours of being constantly set up and torn down, etc). I know when I did the install in my venue, I was going to go for some Belden cable - http://www.belden.com/pdfs/Techpprs/DMX-512.pdf - most of the cables they list were originally intended for RS485 data networks, but as DMX is just a specialised implementation of RS485 anyway, they fit the bill perfectly. I'm not sure how any of those would cope with being used for flexible leads, though. Link to comment Share on other sites More sharing options...
plainman007 Posted March 19, 2012 Author Share Posted March 19, 2012 By CAT5 Cable do you men the same one used for computer lan connections ? Thanks Link to comment Share on other sites More sharing options...
Ynot Posted March 19, 2012 Share Posted March 19, 2012 By CAT5 Cable do you men the same one used for computer lan connections ?Yes. Link to comment Share on other sites More sharing options...
plainman007 Posted March 20, 2012 Author Share Posted March 20, 2012 This is a totally unknown subject for me. Yes I admit again. If you tell me again, ill admit again. What else can I say. Ive not been difficult to help. Ive only said most have been helpful and thanked them. Ive only asked honest and polite doubts. But if you want to say "you dont seem to know anything about this subject", ill humbly accept, what more do you want me to do ?. It may seem im being thick or difficult probably because of the varied culture between the places we come from and maybe my communication 'seems' negative. Ive been a member at several US based forums on different subjects and ive never had anyone tell me im being difficult to help. Maybe its because of where I am from and where most members here are from. I assumed my english was good enough to explain and understand but it seems to be working negatively. Link to comment Share on other sites More sharing options...
plainman007 Posted March 21, 2012 Author Share Posted March 21, 2012 Yes,,,,, ive located CAT5 cable here (150 ohms rated). Available in long run rolls. But the delaer says CAT6 is what people are using to control lighting. But he couldnt explain what kind of lighting exactly. Should I go for CAT5 or CAT6 ? Ofcourse I can google and jump to conclusions but then with an event which is going to run for a month and the launch date just close by I dont want to try to educate myself, and see stuff on google and assume that this is the right thing to do and then make a mistake. So it would be great if you can tell me which route to go. And also if I get CAT5 for a 120 metre run with 20 fixtures on the line will that be equal to using original DMX cable ? And I googled CAT5 and saw how it looks and it has multiple strands. And I also googled to see how to attach it to DMX connectors and didnt get any viable info. Can someone tell me how the multiple strands are soldered onto a 3 pin DMX connector. Thanks Link to comment Share on other sites More sharing options...
Andrew C Posted March 21, 2012 Share Posted March 21, 2012 CAT5 is fine, and CHEAPER than CAT6. That is why he wanted to sell it to you. CAT5 can be soldered to XLR connectors for DMX use. Better would be special "punch down" types, but I suspect you would struggle to get these. It would be best to use the CAT5 ONLY for permanent runs as it isn't particularly flexible. If you have nothing else, then use it with care! Link to comment Share on other sites More sharing options...
musht Posted March 21, 2012 Share Posted March 21, 2012 CAT5 is fine, and CHEAPER than CAT6. That is why he wanted to sell it to you. CAT5 can be soldered to XLR connectors for DMX use. Dinnae solder solid core CAT5 , specially in any application where the cable moves, it will work harden and snap. Also be aware of economy CAT cables with copper plated aluminium conductor. Problem can be partly the nick put in the conductor when stripping the insulation. Only use punch down krone style terminals, get adaptors with punch down to XLR wallplate. CAT5 patch cable is different, it has a stranded conductor and is solderable, with care, the insulation melts back fast. Main problem as a temporary DMX cable is its not got a tough sheath on it, but it is cheap. For maximum flexibility, short XLR F and M to CAT5 plugs, butchered from premade patch lead, with RJ45 back to backs will aloow you to use just standard ethernet patch cables. http://tsp.plasa.org/tsp/working_groups/CP/DMXoverCat5.htm is the tests http://www.pathwayconnect.com/content/view/91/26/ is the standard way of wiring RJ45 for DMX Link to comment Share on other sites More sharing options...
Ynot Posted March 22, 2012 Share Posted March 22, 2012 And I googled CAT5 and saw how it looks and it has multiple strands. And I also googled to see how to attach it to DMX connectors and didnt get any viable info. Can someone tell me how the multiple strands are soldered onto a 3 pin DMX connector.Cat 5 INSTALL cable (the cheaper type) is NOT stranded - it will be 8-wire solid cores and as has been said already NOT suitable for anything but a permanent install. DON'T try soldering this to in-line plugs/sockets, though it should be OK for panel mounted outlets. So build up the infrastructure with Cat 5 install then use proper DMX cable for the leads out to the fixtures. Link to comment Share on other sites More sharing options...
plainman007 Posted March 22, 2012 Author Share Posted March 22, 2012 I just noticed on my original DMX cables which came with the fixtures. It says AVVR 300/300 V. Whats does this mean please ? any idea ? Link to comment Share on other sites More sharing options...
paulears Posted March 22, 2012 Share Posted March 22, 2012 here You really do need to practice with Google - didn't take very long I searched for AVVR 300/300 cable type and up it came! Link to comment Share on other sites More sharing options...
plainman007 Posted March 22, 2012 Author Share Posted March 22, 2012 Ive seen that. Didnt take very long to understand it had nothing to do with my doubts either. Im sure ive heard here itself on this forum if you google "Elvis is still alive" you'll get hundreds of threads validating even that, Link to comment Share on other sites More sharing options...
plainman007 Posted March 23, 2012 Author Share Posted March 23, 2012 Can you please lock this thread too. I myself have had enough of this. Link to comment Share on other sites More sharing options...
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