Home 2018 Forums Crumble Support Current capability of Outputs

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  • #7237
    windy54
    Participant

    Hi,

    Just received my crumble starter kit, programmed the sparkled and used the switch.

    This is going to be great in my code club alongside the microbits.

    I have looked through the posts and found out that the motor outputs can drive 1.5A and that they are short circuit protected.

    A couple of questions on outputs A,B,C,D.
    Are they short circuit protected
    what is the current rating, can i connect a led for instance without a
    limiting resistor.

    thanks

    Steve

    • This topic was modified 2 years, 6 months ago by windy54.
    #7275
    Helen Roberts
    Keymaster

    Hi, Steve.

    Yes: outputs A,B,C and D have a built-in series resistor to keep the current within the absolute maximum in case of short-circuit. This also means that LEDs can be connected directly. Typically, you get 10mA output.

    Hope your Code Club has fun with them!

    Helen.

    #8135
    Dr John
    Participant

    Further question on the capability of the motor outputs:
    Can I connect a 1.5v single cell battery in series with the output to get a faster motor speed?
    I have done this successfully with other robot designs, and therefore use a negative output to actually stop the motor.
    To put it another way: Is the output driver a simple transistor bridge (like L293D) or is it a pair of amplifiers, capable of producing a low impedance output at all voltages?
    I can just read the letters embossed on the chip, but can find no data on it. Thanks

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