# Powered OTG adapter for HP touchpad



## Razor512 (Aug 22, 2011)

USB host seems interesting for the HP touchpad, but the current methods of getting it working seem pretty bulky.

Are there any self contained devices, eg a battery powered USB cable for USB host on the HP touchpad?

I was thinking about building one (but if there already is one then it will be a waste of my time)

(based on this design http://www.jameco.co...tml?CID=altoids
My current plan is to take the design of the altoids tin USB charger, with a few modifications for using 2 AA batteries and upping the voltage to 5V instead of the more common 9V battery and using resistors to bring the voltage down to 5V

(AA rechargeable batteries are more common, cheap and easier to work with)

Then instead of just the standard USB port for charging, I will keep that but also cut the power cables from the OTG cable and solder them to the power connectors for the USB charger, and having the data connectors pass through to the HP touchpad

Is it worth doing, and will it work, or did someone already make one?

edit: found a AA version so even less figuring out for me  http://www.ladyada.net/make/mintyboost/


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## jeddy (Oct 29, 2011)

sounds worth it to me.... I would love to see a how too!

Sent from my cm_tenderloin using RootzWiki


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## macauman (Jan 19, 2012)

http://www.ebay.com/itm/140511174310?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
This one simply works without modification.


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## Razor512 (Aug 22, 2011)

solar power doesn't seem quite able to give 500ma of power especially at that size (5v 500ma from solar generally required a panel 12 inches by 12 inches and direct sun light)

I guess I am going to end up building one so I can at least have USB host with battery power for the USB devices.

I just ordered the parts, and will see if anyone at work has an empty altoids tin.


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## macauman (Jan 19, 2012)

Razor512 said:


> solar power doesn't seem quite able to give 500ma of power especially at that size (5v 500ma from solar generally required a panel 12 inches by 12 inches and direct sun light)
> 
> I guess I am going to end up building one so I can at least have USB host with battery power for the USB devices.
> 
> I just ordered the parts, and will see if anyone at work has an empty altoids tin.


There is a built-in battery. You can charge that via USB or UV light


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## Razor512 (Aug 22, 2011)

finally got around to making the portable powered OTG cable






did not do a very neat job, will work on another version where I use the chargers devices internal USB port

1: Slice open the OTG cable (Slice far enough for what ever length of wire you want to extract)
2: Locate the red and the black wire
3: Cut the red wire as close to the micro USB connector as you can (then strip a tiny bit of the end for soldering)
4: Locate the black wire and strip a small part of it (but do not cut it, it needs to remain intact since the 5th pin is connected to it)
5: Get some extra wire and solder the extra wire to the section of the black wire that you stripped

6: After you are done with that, solder both the black and the red wire to their respective locations on the circuit board

7: Put everything back together and drape the wires out of the front near the LED light. (if needed you can also secure the mess of wires using hot glue)




























PS does anyone know if there are any performance tweaks for ISC, I remember seeing a thread a while back showing stuff like smoother animations and smaller memory footprint but could not find it.


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## Gotrubberducky (Dec 1, 2011)

Have any pictures of the process to build it?


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## silentmage (Aug 22, 2011)

Where did you get the circuit board from?


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## Razor512 (Aug 22, 2011)

the only 2 components needed to make it is a USB charger

http://www.ebay.com/itm/Emergency-USB-Battery-Charger-2AA-with-Flashlight-for-iPhone-4G-3G-3GS-4S-iPod-/180836124278?pt=PDA_Accessories&hash=item2a1aac4676

and a OTG cable

http://www.ebay.com/itm/Micro-USB-Host-OTG-to-USB-Female-Cable-for-Samsung-Galaxy-S-II-2-S2-Motorola-PC-/320866800010?pt=PDA_Accessories&hash=item4ab526d18a

Sorry, didn't have many photos of the build process, was kinda winging it when building it while bored and tired.

I plan to do another (waiting for the parts to arrive from china), the next one will use the USB chargers internal USB port and i will simply run the wire out through the back (or the side, have not decided yet) that way the device will have a cleaner/ more seamless look.

That version will be well documented with photos and a video of the process


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## yeahman45 (Oct 16, 2011)

wow great idea! and nice!

but can i use the portable charger + a Y-cable (one male part connected to otg cable and one male part connected to portable charge + 1 female part for you to connect your devices)... does such y-cable exists?

I am not comfortable modding my otg cable lol

edit : http://www.ebay.com/itm/OEM-USB-Y-Adapter-2-Male-1-Female-Data-Cable-3ft-/170586576573?pt=PDA_Accessories&hash=item27b7c096bd#ht_1601wt_1140

maybe this Y-cable? any idea if it will work? unfortunately it does not ship to my country


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## silentmage (Aug 22, 2011)

yeahman45 said:


> wow great idea! and nice!
> 
> but can i use the portable charger + a Y-cable (one male part connected to otg cable and one male part connected to portable charge + 1 female part for you to connect your devices)... does such y-cable exists?
> 
> ...


You could plug one male into the OTG and the other male into a PC or even a wall charger. The female port needs to be used for the device you are plugging in


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## yeahman45 (Oct 16, 2011)

silentmage said:


> You could plug one male into the OTG and the other male into a PC or even a wall charger. The female port needs to be used for the device you are plugging in


so you mean that this cable will work? instead of connecting to pc or wall charger for power, i can connect it the portable battery right?


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