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Twin USB converter

Community Veteran
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Registered: ‎06-11-2007

Twin USB converter

I have a redundant USB Twin Charger...

On opening it up.... there is a small circuit board with some "discreet" resistors ....  see pics

 

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P1100412.JPG

 

 

P1100413.JPG

 

I am thinking that if I destroyed the resistors, and scraped away the circuit board runs,  I could then solder some joining wires from the four points  ( and the metal shroud ) on the male side, to the two female sides, this would produce a TWIN USB converter.... 

 

Would this work, so that I could use (say) two USB memory sticks, or Memory stick and mouse , in the same socket on the laptop ?

 

12 REPLIES 12
Seasoned Hero
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Re: Twin USB converter

@shutter 

Have you tried it as it is? Just a thought. Depending on the circuit these might be ok left in

Are pins 2 and 3 connected through?  See.  https://www.hobbytronics.co.uk/usb-connector-pinout   If not you could just link through these pins and try it otherwise unmodified but to be honest I don't know if you can just connect the data connections in parallel. If it didn't work then you can try ripping out the other components and adding links. 

Community Veteran
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Re: Twin USB converter

@Baldrick1   Yeah... I did try it with a mouse and a 64gb sandisk  stick.... [-Censored-]ed up the 64gb of music files... fortunately they were the back up... so I bought another stick and re did the back up with a lot more new files ! .

 

Thanks for the linkd

 

Just had a read of that link.... and this bit

 

A USB device must indicate its speed by pulling either the D+ or D- line high to 3.3 volts. These pull up resistors at the device end will also be used by the host or hub to detect the presence of a device connected to its port. Without a pull up resistor, USB assumes there is nothing connected to the bus.

 

seems to indicate that it would not work as a "Straight Through connection"...  or am I reading that wrong... as the "pull up resistors" may be incorporated in the USB stick/Mouse  aka "device" in that wording ? ? ? ? 

Perhaps I need to google some more and see if there is some "on line" way of making a simple twin connector.

 

Seasoned Hero
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Re: Twin USB converter

@shutter 

My reading of this is that it would work as a straight through one to one, if not there would have to be components in all USB leads. However it will not do what you want, that is one to two without the data lines to the two sockets separated by some buffering circuitry powered by the 5V pins. But that's just my thinking...

Community Veteran
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Re: Twin USB converter

OK... thanks for that....  I know I can get a 4 port usb thing...but they are a bit bulky, either as a solid plastic unit, or with 4 floppy leads & usb sockets on the end... but... I would like to use just this small piece as a TWIN usb socket...

so will do some searching... thanks for your "thinking" on this..

cheers

Wink

Seasoned Hero
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Re: Twin USB converter

Hero
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Re: Twin USB converter

@shutter 

I can't help with your goal of getting two devices communicating with whatever you plug the USB converter into, but something tells me that you would need to have some sort of 'hub' circuitry incorporated to control data-flow otherwise how will the two connected devices be identified/separated by the host device?

It seems that it's a 'basic' converter ATM which just provides power for charging two devices simultaneously?

Community Veteran
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Re: Twin USB converter

@Baldrick1  Hmm.... That`s an interesting looking thing.... And for the price, will save a lot of messing about.. ( although that does give me something to do ! !  ) ..

As a point of interest...

I plugged the twin into a USB 3 slot on my laptop... added 2nd mouse... and a Wireless dongle, 

neither registered... and the mouse did not work on screen..

unplugged all...plugged in the 2nd mouse just to check it and it did work with the original mouse in a USB 2 slot ( two mouses working on same screen ) .

So.. as @RobPN  seems that the circuitry is designed for Power sharing between the two female sockets.

 

As best I could do without proper X-Ray equipment ! ! ... see pic below ...

 

 

P1100418.JPG

Rising Star
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Re: Twin USB converter

@shutter 

Just looked inside an old (USB 1?) cheap 4-port hub:

There is a blob of epoxy resin in the middle of the PCB with the legend "U1" in the silkscreen.

It will be a tiny chip that controls the access to the bus through the hub.

Regards,

Alistair

Seasoned Hero
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Re: Twin USB converter

@shutter 

As far as I can see there is no connection to the data pins 2 and 3 on the incoming side, just the power supply pins 1 and 4. Pins 3 and 4 are connected through circuitry on the output side  If this is correct then presumably data can be transferred between the two output ports but not through the incoming one, this being there solely to provide supplementary power.

Having said this I don't understand what's happening with your mouse tests.

Community Veteran
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Re: Twin USB converter

@Baldrick1  Do you not understand what I was describing,.... or do you not understand why the 2nd mouse did not work ??

Seasoned Hero
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Re: Twin USB converter

@shutter 

Sorry. If there are no connections to pins 2 and 3 of the input side of the unit I cannot see how a mouse plugged in to one of the output sockets could work, unless of course the other output socket was in some way connected back to the computer, when I would expect it to work normally.

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Re: Twin USB converter

@Baldrick1 OK>..  normal mouse... in usb slot 1.... works.    plug in that adapter... to usb slot 2... and then plug in a mouse... that 2nd mouse did not work...  however... unplug the adapter from usb slot 2... and plug the mouse into usb slot 2.. 2nd mouse worked... ( did that just to prove that the mouse was not faulty)

 

On your point about pins 2 & 3 ..I shall have to run a test on my multimeter to see if there are any connections regarding those on all the usb connectors...

 

Regardless of the "correctness" of pin numbering.....     assume the pins on all three are numbered 1, 2, 3, 4. 

from left to right....

P1100417.JPG

 

 

As you say... from the male  pins 2 & 3 do not have any connection with pins 2 & 3 on either of the two female sockets..

on the Male socket    with the multimeter set on 200k   pins 1 & 4 show 35.7

 Left side Female shows 35.8 on same pins

Right side Female shows 36.8 on same pins

Pin 1 on all three to metal chassis shows the same   .

Pin 4 on all three to metal chassis shows 00.00

 

 

on the Female sockets.....

Pin2  to Pin 2  shows 60.3

Pin 3 to Pin 3 shows 80.0

 

Left side Female.... Pin 2 to metal chassis shows 35.1   pin 3 shows 51.8

Right side Female.... Pin 2 to metal chassis shows 35.8 pin 3 shows 51.7

 

Pin 2 on left side female to pin 2 on right side female shows 60.2

Pin 2 on left side female to pin 3 on right side female shows 71.3

Pin 3 on left side female to Pin 3 on right side female shows 82.0

 

 

Not sure if that info is any use.... ! ! ! ... 

 

I suppose that if I connected up all the pins 2 and all the pins 3... I would probably be putting a voltage on the signal lines... which could damage the internals of the laptop ? ? ?Huh

 

Having checked out a few ( "made in India" ) videos on you tube on how to make a multi port usb ... it seems they just wire them all in parallel... ( no resistors, except if a LED warning light is fitted) ..  some comments suggest this is only good for charging  (say) two or three phones at the same time...