DIY keychain DMX tester for lighting technicians.

If you work in the event lighting industry then you'll probably have experienced DMX network issues and the mayhem they can cause. One of the biggest weaknesses of DMX is the lack of error detection and the annoying ability to function under fault conditions with random instability. The most common problem is a shorted or broken data line in a network, and this simple tester can detect many of those issues. Note that this tester will not analyse the validity of a DMX stream, although it's very rare that there is a data timing or format issue unless the shadiest generic lighting desks are used. It will also not indicate a reversed data pair, although that's often fairly obvious in a run of lights. I use one of these at work and it does a great job of tracking down faulty cables quickly. Note that officially you are supposed to terminate a network by plugging a connector with a 120 ohm resistor in it at the end of the run of lights. The resistor bridges the two data lines and reduces the risk of signal reflections that can corrupt data at random points in the network. It's not uncommon for veterans of the industry to imply that they actually cause problems. In reality the terminator will most likely show a problem that was already there. For instance, if a broken cable left one of the data pairs floating the lights might still work with just one line, but when the terminator is connected it stops the rogue line floating and brings it to an equal voltage with the good line. That results in no differential voltage and no data, causing the lights to stop working. The coloured connectors were bought from a UK supplier called CPC which is part of the Element 14 group, so I would expect the same connectors to be available from their other outlets around the world. Here are some connector purchase links for the UK. For the 5 pin male XLRs the codes are:- Red - https://cpc.farnell.com/pro-signal/ps... Yellow - https://cpc.farnell.com/pro-signal/ps... Green - https://cpc.farnell.com/pro-signal/ps... Blue - https://cpc.farnell.com/pro-signal/ps... Black - https://cpc.farnell.com/pro-signal/ps... For the 3 pin male XLRs the codes are:- Red - https://cpc.farnell.com/pro-signal/ps... Yellow - https://cpc.farnell.com/pro-signal/ps... Green - https://cpc.farnell.com/pro-signal/ps... Blue - https://cpc.farnell.com/pro-signal/ps... Black - https://cpc.farnell.com/pro-signal/ps... Quarter watt 220 ohm resistors:- https://cpc.farnell.com/unbranded/mcf... And whatever bright red LEDs you can find, noting that eBay generics are fine. Choose a bright connector colour to make it easier to spot in amongst the blackness of the industry. I keep mine on my keyring at times to make sure it's always with me. The slight downside of that is the risk of inadvertently leaving your keys plugged into a light! If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- http://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.