Mitochondrion Mark 5.0: First light

Yeah, this is going to be bright.

That’s the test power board, the test centre board, and the test strip. The power board holds four 16340 Li-Ion cells and a 5 Volt, 4 Amp converter (and some other gubbins). There’ll be four of them, one for each strip. The centre board holds the Teensy, motion sensor, FRAM, and level shifter (and a bunch of other gubbins). The test strip is 144 Neopixel LEDs. There’ll be 800 of them.

Testing reveals a bunch of issues to fix, but at least I’m at the stage of making light.

3 Responses to 'Mitochondrion Mark 5.0: First light'

  1. ratkins says:

    Can haz more detail on the power setup pls? What DC-DC converter are you using and why did you choose 4x 16340s instead of, say, 2x 16650s? What’s your tube diameter?

    Also, have you looked into the APA102 strips people are talking about on the FastLED group? I know you’ve already gone and bought a bunch of WS2812Bs, but the APA102s will be much better for POV effects.

  2. Jez says:

    DC-DC is these little 5V 3A converters, which have a LM2576 inside. The test one is getting very hot, very quickly, so I may double them up, but I’d like to do some current measurement first. There’s going to have to be power limiting in software (just a cap on the maximum number of LEDs on at once) and temperature limits too.

    Lots of 16340 cells add up to a decent length and I’m starting to get really short on length now. With a very slightly larger tube diameter I could have used a smaller number of 18650s, but I’m limiting myself to 25.4 ID tube, otherwise I find the staff gets to be less fun to spin.

    And I’m not going to look at the APA102 strips yet. Maybe for the next version, coz technology marches ever on and you’ve got to freeze the design at some point and just get one built.

    • ratkins says:

      You know about FastLED’s set_max_power_in_milliwatts()? You can get it to clip your brightness to under a certain power level dynamically. It’s really neat.

      So it’s the battery holders around the 18650s that won’t fit in the 24.5 ID tube? Bummer.

      Fair enough on the design freeze. One lesson I’ve learned is no matter how tempting it might be to go to town when you do an order (“I’ll save on shipping!”), never buy more than you need for the current project—by the time you get to use all the stuff, technology will have moved on.

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