USB Mini Hub with Power Switch - OTG Micro-USB (ADA2991)

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Do you ever find yourself saying, “Gee whiz I wish I could plug in 4 more USB devices to my tablet, or microcontroller with USB host, or a Pi Zero?” I did - literally … read more

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I need a powered USB hub for a USB 4G modem I want to attach to a Rpi 3B+

The Huawei Modem in question needs more juice than the Rpi USB port can supply to operate reliably

In your product description for this USB hub

You describe a need to cut the red wire from the USB line, if external power is needed.

Cut the red wire is a bit vague.

Any chance you can provide more detail?

Or a how to video?

If this device will do what I need, even if it needs a little modification, I will buy one, probably more than one.



Hi Nigel,

There aren’t any further directions really. You sever the power connection between the USB hub and the Raspberry Pi, so you aren’t pushing power “backwards” into the RPI through the USB port. I expect “cutting the red wire” is clear once its open and you are looking at it. If it turns out that its not just send us a picture of what it looks like once you get that step and we’ll walk you through it!

If you are going to open the USB hub, you should check to see if the DC in barrel jack is the three pin type, and how easy it would be to modify the hub to disconnect the USB power when the DC plug is inserted.

Should stop a lot of hair pulling months or years from now when you try to re-use the hub elsewhere.


Has anyone actually tried this with a tablet or phone where the OTG
connection is required to make the host act as the master? Does it
charge the host or does the OTG mode prevent the host from accepting the
power that is on offer from the hub? Some people say that the GND and ID pins must be shorted with a resistor rather than a direct short in order for charging to occur while the host is in OTG mode.


Hi Karla,

I’ve used similar products to these with success with Pis and android phones, and found the charge passed through, but without both this product and a range of devices in front of me, I can’t say for sure.

I believe this varies on a device-to-device basis. USB-C rectifies some of these issues so depending on your device that may be an option.

Good luck with the hunt though!


I will not say that the switch on the USB is a basic necessity, but it has a right to exist and is certainly not superfluous.

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