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  1. #301  
    Quote Originally Posted by Wheel_nut View Post
    Revertit, This has been covered in this thread more than once with an adapter such as you have used and also with a butchered cable.

    So, What do you think will happen if you plug the TouchPad through this adapter, into a USB Charger rated at 500mA or 1.0A? .... or even a PC USB Port rated at 500mA?

    The Potential Divider signals to the TouchPad that it can draw up to 2A. The only fail-safe way to implement the modification is INTERNALLY to a Charger capable of supplying 2.1Amps.
    I'm well aware of the Cons of this sort of build, But I also know I am going to be the only one playing around with this thing. I'm not planning on selling these or making them for others, so the responsibility of using it properly is all on me. I just wanted something that I could plug into my desktop computer and use besides the charger than came with the HP.
    I'm just as curious as you were when you dove into your first 12V adapter, Just wanted to see if it was possible, and it works pretty well.
    I'll just encapsulate the unit in potting and it'll look better, possibly put a bright label on it so no one uses it for something else.
  2. #302  
    Hmmmmm.... Perhaps I have grown risk averse but I wouldn't let that device out of my sight. You are relying on the safe implementation of a current limit mechanism in a $5 charger made in a cottage industry somewhere in China. In my experience, if a plug (looks as though it) fits an orifice, someone will stick it in!

    Here in the UK, All portable electrical appliances have to be tested annually and a label applied to the plug stating a "Do not use after" date. Nobody pays them the slightest notice!

    Having proved that the mechanism works, why don't you simply build it into the charger that you are using with your adapter.
  3. #303  
    Only posting this here because it's cheap and from a brand that I trust - after reading this whole thread I doubt it will work with the TP without mods though. Don't blame me if it doesn't. Since it's cheap, perhaps a mod can be made for this device too...I don't know. They do offer a 30day money back guarantee though and no restocking fee.

    $4.86 from Monoprice.com. Product ID 8858. Found under HOME > USB & FIREWIRE > USB Chargers > USB Car Chargers.

    1 Port USB Car Charger 2.1A - Black

    Any feedback?

    Their sales pitch fyi: Charge your USB powered device while on the go with this Car Charger from Monoprice!

    This adapter fits into the cigarette lighter/auxillary power socket in your vehicle and features a single, standard USB A female port. The adapter provides 5V DC and 2.1A output, allowing it to provide full power to even the power hungry Apple iPadŽ devices! (Because of the iPad reference, I am assuming it won't work on a TP because of what I read for the last hour in this thread.)

    A LED on the front of the adapter illuminates to indicate when 12V DC input power is applied to the adapter. The LED is bright enough to see during the day (except in direct sunlight), but not so bright that it ruins night vision or serves as a distraction when driving at night.
    Last edited by chaosdivine; 02/01/2012 at 06:18 PM. Reason: Deflated enthusiasm
  4. #304  
    Quote Originally Posted by Wheel_nut View Post
    Hmmmmm.... Perhaps I have grown risk averse but I wouldn't let that device out of my sight. You are relying on the safe implementation of a current limit mechanism in a $5 charger made in a cottage industry somewhere in China. In my experience, if a plug (looks as though it) fits an orifice, someone will stick it in!

    Here in the UK, All portable electrical appliances have to be tested annually and a label applied to the plug stating a "Do not use after" date. Nobody pays them the slightest notice!

    Having proved that the mechanism works, why don't you simply build it into the charger that you are using with your adapter.
    Oh I plan on it, but like I said, this little unit came in first, and I was anxious to get started on something. Unfortunately the 2.1A units I have coming are taking a bit longer than I had hoped. I recently bought my father a touchpad, and one of the first things he asked for was a car charger, so once I get these in and modded I will give him one. I wouldn't dare let him get a hold of the modified usb adapter. I'm pretty much the only one in my house who plugs things in etc, So I'm confident it won't fall into the wrong hands.
    I appreciate the safety concerns, but I'm confident no one else will get their paws on this unit.
  5. #305  
    Quote Originally Posted by chaosdivine View Post
    Only posting this here because it's cheap and from a brand that I trust - after reading this whole thread I doubt it will work with the TP without mods though. Don't blame me if it doesn't. Since it's cheap, perhaps a mod can be made for this device too...I don't know. They do offer a 30day money back guarantee though and no restocking fee.

    $4.86 from Monoprice.com. Product ID 8858. Found under HOME > USB & FIREWIRE > USB Chargers > USB Car Chargers.

    1 Port USB Car Charger 2.1A - Black

    Any feedback?

    Their sales pitch fyi: Charge your USB powered device while on the go with this Car Charger from Monoprice!

    This adapter fits into the cigarette lighter/auxillary power socket in your vehicle and features a single, standard USB A female port. The adapter provides 5V DC and 2.1A output, allowing it to provide full power to even the power hungry Apple iPadŽ devices! (Because of the iPad reference, I am assuming it won't work on a TP because of what I read for the last hour in this thread.)

    A LED on the front of the adapter illuminates to indicate when 12V DC input power is applied to the adapter. The LED is bright enough to see during the day (except in direct sunlight), but not so bright that it ruins night vision or serves as a distraction when driving at night.
    I've had good luck with all Monoprice stuff, but like you said, it needs to have the correct ckt to allow for current draw. Good price on that unit though, the units with two ports seem to be a lot handier.
  6. #306  
    Quote Originally Posted by Revertit View Post
    I've had good luck with all Monoprice stuff, but like you said, it needs to have the correct ckt to allow for current draw. Good price on that unit though, the units with two ports seem to be a lot handier.
    You will find that ease of opening and closing the case without doing visible or functional damage is worth more than a few Dollars on the price. See my Avatar for the one I use which I can modify without damaging the case. There is a single port model which is easier to open but the preference seems to be for a two port unit capable of powering a Veer or Pre as well as the TouchPad.
  7. #307  
    Quote Originally Posted by Wheel_nut View Post
    You will find that ease of opening and closing the case without doing visible or functional damage is worth more than a few Dollars on the price. See my Avatar for the one I use which I can modify without damaging the case. There is a single port model which is easier to open but the preference seems to be for a two port unit capable of powering a Veer or Pre as well as the TouchPad.
    Ah yes, I was going to ask you about that one, looks like it would be an easier one to work on due to size. Do you have a model number/brand for it?
  8. #308  
    I have been buying from this seller in the UK but you will see that he is now asking a ridiculous price (10 times the real price) which suggests that he doesn't have any stock.

    Mini 12V-24V DC USB 2 Port Output Car Charger Adapter For iPad iPhone 3G-S 4G 4S | eBay

    The problem with buying these is that even they look the same in the pictures, the innards can be radically different; some being a single chip design and others a 2 chip design. This is why I am looking at alternative designs/sources and the reason that I posted the survey in this forum. My stock is down to 3 units now so yes, I need to decide what I want to do .... if anything!

    There is an alternative that looks good but I haven't bought one yet so can't tell you what's inside:
    eBay - The UK's Online Marketplace
  9. #309  
    Quote Originally Posted by Wheel_nut View Post
    I have been buying from this seller in the UK but you will see that he is now asking a ridiculous price (10 times the real price) which suggests that he doesn't have any stock.

    Mini 12V-24V DC USB 2 Port Output Car Charger Adapter For iPad iPhone 3G-S 4G 4S | eBay

    The problem with buying these is that even they look the same in the pictures, the innards can be radically different; some being a single chip design and others a 2 chip design. This is why I am looking at alternative designs/sources and the reason that I posted the survey in this forum. My stock is down to 3 units now so yes, I need to decide what I want to do .... if anything!

    There is an alternative that looks good but I haven't bought one yet so can't tell you what's inside:
    eBay - The UK's Online Marketplace
    I purchased a few different styles to experiment with, so when they finally come in I'll let you know what I find.
    I've had very good luck with stuff off of Meritline.com, the only problem is if it gets shipped from China it takes a while to get to where ever you are located.
  10. csaket's Avatar
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    #310  
    How easy is it to take this apart?
    Do you have pics of the modified circuit?


    Quote Originally Posted by jblather View Post
    I found a 4-port USB car adapter at Meritline that will supply a total of 2.1 Amps. $5 shipped.

    Using the information supplied by wilywyrm in post #98, I opened it up, studied the circuit and found that removing just two resistors will result in two of the ports supplying 2.1 Amps. No need to add resistors. There are already other resistors in the circuit for the voltage divider. To get the Touchpad to recognize this adapter as capable of supplying 2 Amps, just remove two of the resistors.

    $5 each, free shipping:
    Universal 4-Port USB Car Charger Adapter for Mobile Devices

    The four USB ports are split into two circuits, two USB jacks per circuit. Each circuit is identical. I removed R4 and R10, which was really easy because they were on the edge of the circuit board. Then I ran a bit of solder between the middle two pins of that USB jack pair. It was real easy, didn't have to add any components. Removing just R4 and R10 and creating the small solder bridge modifies just two of the USB ports.

    The other circuit is still stock, so you can still use the other two USB ports with your smartphone.

    If you want to modify all four ports, also remove R7 and R12 and solder together the two middle pins of the USB jack on that side. Easy.

    Tested, works great.
  11. #311  
    Hi to all, I would just like to add my support for Wheel_nut and his efforts in supplying the community with a working Touchpad car charger. This week, I took delivery of one of his modified chargers and like previous buyers, I can vouch for it working. Well done mate, you've saved this electronically challenged duffer from a lot of frustration. Keep up the good work!
    jblather likes this.
  12. #312  
    Quote Originally Posted by csaket View Post
    How easy is it to take this apart?
    Do you have pics of the modified circuit?
    Sorry, no pics at the moment. I will try to post later.

    You can take it apart with no tools. Comes apart in about 15 seconds, no tools needed. Unscrew the end with your fingers, remove the annular ring, then just pull it apart. It goes back together just as easy.

    If you're good with a soldering iron, it takes less than 10 minutes to do everything including putting it back together.

    The results in two ports that supply 2.1A combined and another two ports that are unmodified. I used a sharpie to mark the modified 2.1A port.

    Nice thing is that these parts are really cheap ($4.99, free shipping). I ordered two just in case I destroyed one and wound up modifying both units. I keep one in each car.

    OR....you can just buy one of Wheel_nut's units and be done with it.
    csaket likes this.
  13. csaket's Avatar
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    #313  
    Quote Originally Posted by jblather View Post
    Sorry, no pics at the moment. I will try to post later.

    You can take it apart with no tools. Comes apart in about 15 seconds, no tools needed. Unscrew the end with your fingers, remove the annular ring, then just pull it apart. It goes back together just as easy.

    If you're good with a soldering iron, it takes less than 10 minutes to do everything including putting it back together.

    The results in two ports that supply 2.1A combined and another two ports that are unmodified. I used a sharpie to mark the modified 2.1A port.

    Nice thing is that these parts are really cheap ($4.99, free shipping). I ordered two just in case I destroyed one and wound up modifying both units. I keep one in each car.

    OR....you can just buy one of Wheel_nut's units and be done with it.
    Thanks.
    I will order this and see how it goes.
    Do post pics if/when you can.
  14. #314  
    Here is a pic of the insides. As you can see, There are two resistors at the top, R4 and R10. Simply remove those (red circle) and then bridge the two pins nearby (yellow arrow). The white arrow shows what the two pins look like before soldering them together.

    As you can see, the upper half and lower half of the circuit is pretty much identical. The upper half was modified to provide 2.1A to the touchpad. The lower half was left alone.

    Then I used a sharpie to mark the outside of the case so I can see which jacks supply 2.1A (max combined) and which supply the default 500mA.
    Attached Images Attached Images
    noseph likes this.
  15. #315  
    Quote Originally Posted by jblather View Post
    Here is a pic of the insides. As you can see, There are two resistors at the top, R4 and R10. Simply remove those (red circle) and then bridge the two pins nearby (yellow arrow). The white arrow shows what the two pins look like before soldering them together.

    As you can see, the upper half and lower half of the circuit is pretty much identical. The upper half was modified to provide 2.1A to the touchpad. The lower half was left alone.

    Then I used a sharpie to mark the outside of the case so I can see which jacks supply 2.1A (max combined) and which supply the default 500mA.
    Not sure if I'm reading this correctly, but did you add new resistors to this unit?
  16. #316  
    Quote Originally Posted by Revertit View Post
    Not sure if I'm reading this correctly, but did you add new resistors to this unit?
    See Post #293. Jblather did not add resistors but used ONE of the potential dividers in the Apple spec Charger to provide the 2.7V in the bridged Data lines as required by the TouchPad.

    Whereas this provides approximately the correct voltage on the Data lines, the Apple spec Potential Divider uses much lower impedances (~75K/51K) than that specified for the TouchPad (300K/ 240K). During the experimentation with Wilywrm and RickV early in this thread, I found that using a low impedance potential divider caused my TouchPad to become erratic and unresponsive to the Touchscreen. Because of this, I always replace the resistors with the specified 300K/ 240K values.

    However, what works for you works for you
    Last edited by Wheel_nut; 05/20/2012 at 04:16 AM.
  17. #318  
    No it wouldn't work for all the reasons that have been discussed inthis thread.

    PM me if you want one that is custom modified to work with the TouchPad.
    Mutoidi likes this.
  18. #319  
    Quote Originally Posted by Wheel_nut View Post
    No it wouldn't work for all the reasons that have been discussed inthis thread.

    PM me if you want one that is custom modified to work with the TouchPad.
    Your patience amazes me Wheel_nut!
    I guess it's a long thread for people to successfully plough through in order to eventually reach that same correct conclusion though!

    No surrender!

    Wheel_nut likes this.
  19. noseph's Avatar
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    #320  
    Maybe the OP or a Moderator can modify the first post in some way to make more of a point that there are no commercially available car adapters for the TouchPad.

    Maybe change:
    Please read the thread before posting! No charger has been found to deliver the full 2 amps needed, the only solution is to modify one by removing resistors and adding new ones. Modified ones are available from the member Wheel_nut.

    To this:
    Please read the thread before posting! No charger has been found to deliver the full 2 amps needed, the only solution is to modify one by removing resistors and adding new ones. Modified ones are available from the member Wheel_nut.

    Just a thought
    Last edited by noseph; 02/16/2012 at 12:53 PM. Reason: grammar correction
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