USB wedge - 5V power interruptor

This is a simple project to interrupt the power of a USB cable

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I plug and unplug USB cables continuously all day and every day. My cable connectors get loose, sockets get worn out, and my concentration gets broken.

This project interrupts the 5V of a USB connection. It sits on the high side of the circuit so that any shared grounds to other test equipment/devices don't leak current.

My first board iteration was simply a PNP (S8550) transistor and a normally closed button that sat inline with two cables.

My second board iteration replaced the S8550 with an AP2171 so that it can switch up to 1A instead of 500mA of current. This board also improves on the original in that a break out pin can be controlled by a microprocessor.

I use these to deploy software to a board via VFAT partition over a USB connection.

First board iteration is available on Tindie: USB micro wedge

Second board iteration is also available on Tindie: USB power micro wedge (5V programmable)

Limited quantities!  While supplies last!

  • outline

    George05/17/2018 at 05:53 0 comments

  • revision 3

    George05/17/2018 at 04:13 0 comments

    Revision 3 of the board came in and I quickly soldered it together and it works.

    I can control the USB port with either a 3.3V/5V MCU!  This should be ideal for automation testing and deploying code.

  • salvaging botched PCBs with bodges

    George05/16/2018 at 01:53 0 comments

    One other thing I didn't notice with the new PCB design was that the USB A connector had its wiring completely reversed in EasyEDA.  I sourced the components and PCB fab through LCSC and JLCPCB, and they were super helpful in refunding my money for the mistake, even though there were already a couple of other mistakes on the board.

    Here we have some bodge wires and some TH components to further test and validate the new design.

  • cost down boo boo

    George05/16/2018 at 01:49 0 comments

    In an attempt to bring the PCB cost down, I spun up a new design, and added support for 3.3V to 5V logic toggling of the AP2171.  Too bad I didn't notice the copper pour was messed up when I uploaded my Gerber to the fab.

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John (EBo) David wrote 12/29/2023 at 15:29 point

If I understand the use-case correctly, how I solved that problem is to use cables with magnetic ends on them.  That way I can say connect my cell pone to the charger once or twice a day without having to unplug the connector (just disconnect the magnetic connection).

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ssvenn wrote 07/26/2018 at 13:41 point

This project made me curious what types of commercial products exist for switching off and on USB power.. after some digging i found - turns out a couple of USB hubs has software switchable power functionality built into the chipset!

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