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Multi Switch

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  • Multi Switch

    Hi all,

    Is it O.K. to connect a bipolar transistor's base to the "PRESS" switch? (the b. e. parallel to R5).
    I need it as an electronic ON/OFF switch. (A very long press indicates on/off toggle )


  • #2

    Since I won't know exactly which circuit you are referring to R5 in, it's a bit hard to say.

    Assuming the circuit you are referring to is in Section 4.2 of the datasheet for the uOLED-96-G2.

    It's a bit of a worry, eg a) expecting a bipolar transistor to do something useful with 0.67v will depend on the rest of the circuit and b) the loading it presents might stop Goldelox from seeing the PRESS button.

    Other ideas are a) a FET, or b) getting Goldelox to detect the long press and toggling IO2.

    As for the applicability of any of these suggestions, it depends on what you are really trying to achieve/do.


    • #3

      Yes, the R5 is from the datasheet.
      As far as I know a general purpose silicon transistor will saturate at Vbe=0.6V... Ic=100uA.
      The Plan is to connect the collector of the transistor to the gate of a P-Channel mosfet that it's source is connected to the battery and plays the role of the ON/OFF switch. Software will pull down an I/O pin to keep the gate low thus the supply current to the circuit is not interrupted after the push button is released.
      A FET is of no use because of the 0.65V.... even with "logic level mosfet" Vgsth is more then 1V.

      I'll try to upload a diagram


      • #4

        Hi all
        The circuit attached works fine.
        I used the second OLED's module IO to control the MOSFET

        Thanks Attached files