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How much current can you draw from a JoyconEX LED port?

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  • How much current can you draw from a JoyconEX LED port?

    I'd like to connect a small relay to the LED port on my JoyconEX to turn my screen on and off.

    At night I'd like to be able to turn the display on and off using the steering wheel controls. So, I was thinking I could connect a relay to the LED port on the Joycon and the relays contacts to the power button on the display.

    The relay I have draws less than 20mah at 12volts. I'm guessing it will be fine, but didn't see any specs for how much could be drawn. Anyone know?

    If anyone has a different way of accomplishing the same thing I'm open to ideas.

  • #2
    Thinking about it I bet the output is only 5volts, being a USB device and all.
    I need to dig into the car to do some testing but I'd still like to know how much current can be drawn from it.


    • #3
      after comparing some pictures of the carpc joycon, and checking digikey, i estimate that the led that they are using consumes about 10-20mA, at about 2v(similar led's appear to be rates for around 1.8-2.1v) also, they could also be under-driving it to help preserve the life of the led, so it could be using less then 10ma...
      My OLD 2001 Mitsubishi Eclipse GT:
      "The Project That Never Ended, until it did"

      next project? subaru brz
      carpc undecided


      • #4
        You need a FET or transistor as a buffer to trigger the separately powered relay.
        Or use an optocoupler etc.


        • #5
          Thanks guys,
          Not much current I guess, and I think you're right about not driving the relay directly. Easy enough and safer to use a transistor or optocoupler.
          As luck would have it, I salvaged some opto-couplers from the same modem the relay came off of so we're good to go. Now I've got something to do tonight.

          Thanks again,


          • #6
            I grabbed more of the cards from the modem today and looked at some of the other components on it.
            There is a transistor and a darlington output coupler and three optomos relays. The relays look interesting. No bounce or inductance spike.
            I might be able to use a single resistor and the relay (LCA111e). Just connect the displays power button to the relay and call it a day.

            Fun stuff.


            • #7
              JoyCon developer told me that led ports output is 5V and 500mA max, which is USB port max output.

              I have one Fujitsu SY5WK relay connected and works fine. Relay's specs are 24V 1A, coil is 5V 170ohm. I don't know how much current that relay use for pull, so I'm not sure is't possible connect two of those relays.


              • #8
                Thanks for the info Dartman,
                I ended up using one of the optomos relays. The LED has a voltage drop of 1.5v so with a 175ohm resistor it's only drawing about 20mah.
                I just hooked up some wires to the displays on/off switch and it's working perfectly.

                I've got 8 spare relays if anyone is interested in one. It can only handle 120mah so it might be somewhat limited.
                If anyone would like one just PM me.

                Thanks again
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