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I have been working on a project to make my own laser tag gins and sensor vests.

I have completed the electrical side of my design but this is the first time I have designed something like this and have a few questions regarding some design decisions I have made. First just some background info. I have attached the layouts for my backpack and the gun. The comms cables between my boards are just running a 10khz bit banging protocol I have created. And the IR sensors and emitter will be running at around 1khz. The leds are ws2812b so are running at around 4mhz on the signal line. All the boards have a ground plane with a ground pour and via stitching on the top layer. The sensor board has 3 isolated ground planes for the motor, led and ir sensor. The diode boards just have a load of IR and normal LEDS and the required transistors and resistors. I also have more 2 strips of sensor boards in the backpack. These are wired the same but not shown in the diagram. In the backpack diagram, the green cables are the led comms, orange is IR output from TSOP sensor and blue is the motor turn on signal.

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My questions are:

  1. The battery for the whole system is in the backpack. I have lots of pairs of power cables running to the power board in the backpack to keep various things isolated. Would it be ok to link these all together in the gun, maybe adding a voltage regulator and some caps where they connect, and run a single pair of power cables back to the supply. Or just run less pairs and run a few devices off the same pair. Also, should I do this for my sensors or keep the 3 separate power runs for motor, led and IR sensor.

  2. Have I gone overkill with the amount of separate power cables. For example would it be better to run the power for my IR sensors directly from the PCBs power or is having separate power feeds for them a good idea. The actual main IR emitters have a separate power connection on the main PCB which is linked to the boards main ground plane.

  3. I haven't added return ground cables for anything that is just a low level signal to turn something on/off with a transistor. For example the non PWM leds on the gun diode board or the turning on of the motors. But is it necessary to have the negative return cables for my comms cables between the two boards as they're only running at 10khz.

I think that covers anything. Thanks in advance for any advice.

Dave Tweed
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Shayne Colbert
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  • please proper punctuation .... i do not see any question marks in you post – jsotola Mar 03 '19 at 19:34
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    upvote for well described project – jsotola Mar 03 '19 at 19:38
  • connect as few systems as possible to the gun because of the amount of flexing in the attached cable ........... interconnect all modules with the least number of cables ..... run power and data in same cable – jsotola Mar 03 '19 at 19:48
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    Welcome to EE.SE! In general, we discourage broad, open-ended design review questions here, because the answer(s) tend to become long strings of unrelated edits and/or comments. While this might help you with your immediate problems, it is of no value to the site overall. We DO allow design review questions in which you explain your choices and then focus on a few points about which you still have doubts. To get a better feel of what is or is not acceptable, search for "design review" on the meta site. – Dave Tweed Mar 03 '19 at 20:04
  • You should probably build one copy with eval boards breadboards or whatever and try it in various lighting. Not clear if you are actually modulating the IR and detecting specifically that but you definitely need to. – Chris Stratton Mar 03 '19 at 21:36
  • I don't know why you need so many power supply lines. A few decoupling capacitors would do instead. Every wire you have trailing from one bit of kit to another is a possible failure point. These things will be moving about constantly as people are running around. – Simon B Mar 03 '19 at 21:45

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