This effort is a do-over. I have had the scoreboard running for about two years. For those two years, the data came from the control box to the panel using a flat ribbon cable. I’m not sure what gage (gauge?) the wires are in that ribbon cable, but they are TINY. I had a separate, but much larger cable that powered the digits. It powered all four digits, and that was one of my problems. I had a single voltage regulator that was supplying all power for the panel, and I was definitely exceeding the 1.5A that the board was rated for. Since I decided to add a second regulator, I thought it might be best to also route that power separately. And that’s when I got to thinking about whether I should have a completely different battery for the panel.
It sounds like electrically, it is OK to use the common ground, so I suppose it does make sense to use only one ground symbol as well in the schematic.
I wasn’t aware that CAT5 used the same size wires as I was planning here! The molex data sheets said the pin connectors were rated at some crazy high amperage, so that sounded great. I hadn’t thought that while the connectors were rated high enough, the wires may not be. I can certainly go back to using separate but larger wires for the board power. I think I will do that, since I have the chance now to do it right.
Yes, the board is used outdoors. It is for Ultimate Frisbee, which we normally play “first to 15”. You have to win by two, so rarely we go into the twenties, but it does happen. Definitely the most power drawn would normally be something like 18-18 (or 16-18, 16-19, you get the point). That score could be up there for several minutes. Do you think I still have some power concerns other than what we have talked about here?
Strike that entire paragraph. I had forgotten that you were using two different regulators. Unless you really know what you are doing, don’t connect the output of two different regulators to each other. It is perfectly fine and acceptable (and often necessary) to connect their grounds together though. Just remember that ground return needs to carry the same current as both regulators combined.
I would probably approach things differently. I would put an arduino (or more likely make my own board with everything on it) in each display box and connect it to the controller with RS485. Using the cat5 cable, that would give you 3 wires each for Vcc and GND, and one pair for RS485. This way, you can get away with one cable (if it’s too long, shove a higher voltage up the cable and use a buck converter in the display box). I did something similar for the last remote LED display I made.
Also, don’t forget to derate the TPIC6A595. There’s a per-pin limit of 350mA and a total power limit, shown in the graphs, based on ambient temperature and number of segments on.
Hi … I have only just briefly read through the thread - I was referred from another thread - yet notice that it seems the OP will be using LiPO batteries to power his circuitry. Which may be fine … I do, however, not see any low voltage cut-off circuitry and would like to mention that they typically do not like to go under ~3 volts.
