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amateur wearable electronics: best way to accomplish male-to-male JST PH connection?

CalicaCalica Registered User regular
I have:
  • a LiPo battery with a female JST connector
  • a JST extension cable with switch - one end each male and female
  • a pass-through USB charger for the LiPo battery with two male JST connectors - one for the battery and one for the project electronics (plus a USB socket for the power source)
  • a cable with a female JST connector on one end and bare wires on the other (came with the charger)
  • a Gemma microcontroller board with a male JST connector

The battery will plug into one JST connector on the charger, and the extension cable will plug into the other. That leaves me with a male JST connector on the free end of the extension cable, which I need to connect somehow to the male JST connector on the Gemma. I also have an extra female connector attached to the cable that came with the charger. Possible solutions:
  • Replace the male connector on the free end of the extension cable with the extra female connector
  • Plug the extra female connector into the Gemma, remove the male connector from the free end of the extension cable, and join the two cables via their exposed wires
  • Acquire another female connector and attach that to the bare end of the extra cable, then use the now female-female cable to bridge the male end of the extension cable to the male connector on the Gemma

They all seem kind of silly for different reasons. What's the best approach here?

This is for an LED hat for a three-year-old, so assume it's not going to be treated gently. The Gemma, battery, and all connections are going to be as well-protected as I can make them, though.

I've never soldered anything before, but I do have soldering equipment. I had planned to sew all the circuits with conductive thread, but that obviously won't work for this situation.

(Given that the battery has a female JST connector, and the charger is a male-male component meant to sit between the battery and whatever it's powering, why on earth doesn't the charger come with a female-female connection cable by default?)

Jedoc wrote: »
The GOP cares about babies until they're born, soldiers until they're in need of care, and families until they interfere with stockholder dividends.

Posts

  • DaenrisDaenris Registered User regular
    If it was just something for me personally to use, I'd probably just go with your second option. But since it's for a kid and likely to be taking some abuse, then either options 1 or 3 sound reasonable. Obviously option 1 doesn't require you to get another connector, so you could do it now. Shouldn't be too hard to do even if you've never soldered.

    And yeah, it's weird to me that the charger isn't one of each.

  • tynictynic PICNIC BADASS Registered User, ClubPA regular
    edited October 2019
    unfortunately whatever gremlins decide on component connectors always seem to come from parallel universes, they never include all the things you might actually need.

    Easiest and most robust plug and play solution is to have the correct male/female connectors going into each other, so I'd probably go with option A unless there's some reason not to that I'm missing.
    Do you have heat shrink wire wrap/ are you willing to buy it? (digikey is cheap and easy to buy things from) If you end up needing to do wire-to-wire soldering, just make sure you get a long soldered connection (rather than a blob) and then secure it with heat shrink, it should be pretty resilient.
    Can't give any more advice without knowing exactly what you're trying to make, but conductive thread is pretty flimsy and tends to have a brittle connection to component sources so if a kid is involved I would make sure all the functional parts are contained within the fabric - they're not gonna hurt themselves at those low voltages but it's easy to break the connection.

    tynic on
    Calica
  • CalicaCalica Registered User regular
    tynic wrote: »
    unfortunately whatever gremlins decide on component connectors always seem to come from parallel universes, they never include all the things you might actually need.

    Easiest and most robust plug and play solution is to have the correct male/female connectors going into each other, so I'd probably go with option A unless there's some reason not to that I'm missing.
    Just that it looks really fiddly to take apart a female connector without ruining it. But I could always get extras; they're cheap enough.
    Do you have heat shrink wire wrap/ are you willing to buy it? (digikey is cheap and easy to buy things from) If you end up needing to do wire-to-wire soldering, just make sure you get a long soldered connection (rather than a blob) and then secure it with heat shrink, it should be pretty resilient.
    I have heat-shrink tubing, yes. Might put some over the connection even if I go with option A.
    Can't give any more advice without knowing exactly what you're trying to make, but conductive thread is pretty flimsy and tends to have a brittle connection to component sources so if a kid is involved I would make sure all the functional parts are contained within the fabric - they're not gonna hurt themselves at those low voltages but it's easy to break the connection.
    Project description:
    My niece is super into unicorns. I'm going to knit a unicorn hat - i.e., a basic earflap hat with ears, a horn, and a mane - and use LEDs and optic fiber to light the horn and make little firefly sparks in the mane. The LEDs and their circuits will be sewn to a strip of felt running over the crown of the hat, beneath the mane. (If I can't avoid soldering entirely, then I might as well use proper wire and solder those connections too; but they'll still be sewn down.) The fiber optic bundles will be attached to them with heat shrink tubing and liberal application of hobby glue.

    The microcontroller, charger, and battery are each about the size of a quarter. They will be in one or more small plastic boxes - I'll have to see what works best given the limited space - and attached with conductive Velcro, since the battery needs to be removed for washing and I'd rather not depend on the JST connectors to hold up to being plugged and unplugged repeatedly. If I wind up with separate boxes, I'll enclose them in fabric or something to make sure the wire stays slack when they're handled.

    The kid will be able to turn the lights on by connecting the earflaps using more conductive Velcro. The circuit for that will be hidden inside i-cord. I figure braided conductive thread would be good for that, since it'll need to flex a lot. The actual power switch is mostly for the parents :razz:

    The part of this that's most likely to break under reasonable abuse, I think, is the individual optic fibers - but a fiber still glows if you break it; it's just shorter. And I spent some time flexing a piece, deliberately trying to break it; it's a lot less brittle than whatever they were using when I was a kid.

    Jedoc wrote: »
    The GOP cares about babies until they're born, soldiers until they're in need of care, and families until they interfere with stockholder dividends.
    Zilla360tynicmightyjongyo
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