DrWizard

So I'm debating buying or building a DMX splitter in order to split my yard into 'zones' and avoid so much wire criss-crossing the yard. I understand the reasoning/advantage behind opto-isolation, but the question is, do I really NEED isolation as it substantially increases the complexity and cost. There are some very cheap RS-485 to TTL converters on fleabay, 5 for $5 (US seller, even cheaper from China) and I was thinking of using 1 as the receiver, and connecting it's TTL data output to the TTL data input of the other 4 (as transmitters), and driving them all from the same 5V power supply that runs my controllers and other stuff. All my controllers are grounded and on the same circuit. Any problem with this?

I use CAT5 twisted pair wire. I use the 4 white wires for ground, 3 of the colored wires for power, and the final colored wire for data. That way the data and ground go thru a twisted pair. I have some pixels that are 100' away from the controller, and data-wise at least, this is not a problem with twisted pair. Voltage drop is still an issue though, so I power-inject using heavy gauge extension cords meant for 120V. I use different plugs tho so no confusion. (Would hate to plug my pixels into 120 volts!)

I think the strips (in the silicon tubes) look better for outlining, and definitely cheaper. Problem is, when you get a bad pixel, they are a real pain to get out of and back into the silicon sleeve. All of my pixel failures appear to have been moisture related, and now I make sure to silicon the heck out of the ends where the wires come out, and I have had no more problems. Don't get the strips that are just epoxy coated. The coating turns yellow and cracks pretty quickly in the sunlight.

I wasn't sold on vamp plugs either, until I finally tried some a few years ago. The electrical engineer in me had a bad gut feeling about them. But now I love them! I can make all my cords the exact length I need them, with multiple outlets exactly where I need them. And far cheaper in the long run. I now have somewhere around 2000' of spt-1 wire, around 60 male and 200 female plugs, and much to my pleasant surprise, I have had absolutely ZERO bad connection problems. Moisture issues have not been any worse than they were with premade cords. The only critique I have with your cord is that perhaps green would have been better aesthetically.

I have been mulling over the idea of multiplexing 120 Volt AC channels, and I was wondering if anyone can tell me reasons why I couldn't or shouldn't do this. I'm planning 8 minitrees, each with 4 colors of 120vac LED strings which I'm assuming are probably half-wave. My thought was to use 2 dirk cheap [4 channel] SSR boards to control the hot wire going to each of the 8 trees, and another dirk cheap to control the neutral wire going to the 4 colors. 1) Yes, I know switching the neutral is highly frowned upon, and I wouldn't get a UL rating. 2) I know this would not work with incandescent lights which are just resistive and so there would be feedback loops thru the matrix and lights would come on that I didn't want to. 3) Likewise, I know I will need to get all the half-wave LED strings 'facing the same way' diode wise, so that again, there are no feedback loops. Because of the switched neutral, I thought of maybe running the power thru an isolation transformer first for safety reasons. Not sure that that really improves things though. If you touch the hot wire (without an iso transformer), you're gonna get zapped no matter what. Matrix or not, neutral switched or not, the hot is still hot. And I also am considering going thru a full-wave bridge rectifier (after the transformer, before the SSRs) (rated for sufficient current and voltage of course) to make them brighter. Any thoughts on this?