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DIY iPhone Charger
Finally, after a few weeks of waiting, I've managed to proof that my iPhone charger concept works! Special thanks to Jia Ying who helped me buy components from Pudu. Here's how to build your own iPhone charger:
All you need are the 4 resistors stated above. I have modified some values of the resistors because of some miscalculation. Connect them as shown and provide the circuit with a regulated 5v supply. Get a female USB plug and connect it as shown to the circuit. Make sure the positive and negative terminals are connected correctly. The D+ and D- pins have low currents so connecting them wrongly may not blow up your iPhone.
Once you are done, triple-check your circuit. Use a voltmeter to make sure everything is correct. Then plug in your iPhone and you should be greeted with the charging chime, indicating that your iPhone is now charging properly.
Practical application: In-car iPhone charger.
A normal cheap car USB charger.
I have tons of USB car chargers lying around because it seems like every device that I buy comes with one free. These chargers are very simple in construction. They take in 12V and they output a regulated 5V to the USB ports. These cheap chargers will not work with the iPhone because the D+ and D- pins are not connected. I can remember at least one incident when I need to charge my iPhone but couldn't because I didn't have the proper car charger.
This charger is a bit special because it uses switching (pulse width modulation) to get 5V from 12V.
So with the circuit diagram above, I constructed the voltage divider circuit and put it into the charger. It's wrapped in tape to prevent it from shorting.
It works!
Now I can charge my iPhone when I'm traveling long distances.
Other practical applications: External battery.
Get a high capacity battery (8.4v @ 3000mah for example) and use a 7805 to regulate it to 5v. Then feed it to the circuit above and you'll be able to charge your iPhone when you're not in a car or near a wall socket. If you use 6 AA batteries (9v), you can charge your iPhone anyplace where you can find batteries. That's almost anywhere in the world! The days of running out of juice is over!
Disclaimer: I will not be responsible if you destroy you iPhone with the information posted here. I have tested the circuit and it works perfectly with my iPhone. If you plan to build this circuit, please triple-check everything before plugging your iPhone in. Happy charging!
Update: DIY iPhone 3G charger. Also explained: why the iPhone charges when reference voltages are applied.
Posted on Sunday, June 29 @ 17:18:11 MYT (81719 reads) by tzywen |
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 About Me |
With 21 years of real life experience, this is where I put them to good use. Here, I post up snippets of my life, interesting things that I do, current projects, outings and events and sometimes something very random.
Currently with MAS studying for my aircraft maintenance license, I'm passionate about my job (or technically my future job), computers, gadgets, electronics, cool stuff, cars, technology, and the environment. I love sports, traveling and enjoying nature. I unwind by sleeping.
Check back here often. I update at least 7 times a week.
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| "DIY iPhone Charger" | 191 comments | Search Discussion |
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Post Comment | | The comments are owned by the poster. We aren't responsible for their content. |
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| I am SOOOOOOOO happy you developed this...! Thanks... May I make one simple suggestion cutting down the power consumption and the component count...
Rather than use to PD networks, how about using three resistors in series and tapping voltage from the three. Less power consumed and fewer components!
Again, thanks!Posted by: Howard on Monday, July 21 @ 11:13:34 MYT |
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| Howard: yes, that design will work too, as long as you provide the proper reference voltages to the iphone.
glad you found it useful!Posted by: tzywen (http://tzywen.com) on Monday, July 21 @ 23:04:24 MYT |
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| Very basic diagram without drawing below...
5v---|-----100k-----|----20k-----|----100k----|-----0v
----5v--------------2v-----------1.8v---------0v-------Posted by: Howard on Tuesday, July 22 @ 06:29:44 MYT |
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| Thanks for the diagram. Have you tested this out yet?Posted by: tzywen (http://tzywen.com) on Tuesday, July 22 @ 12:18:25 MYT |
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| I'm curious why you need two seperate voltages for the data lines. It seems to me that being differential pairs, they should probably both sit around 2.5 volts when not signaling, but I am not familiar with the spec, so I could be mistaken. Anyway, if so, you could eliminate another resister.
I do know that you can reverse them and the port will usually still work, which I think reinforces my idea.
Someone should kick apple in the nads for doing it that way. There's no real reason except to force the less technologically savvy into buying their overpriced accessories.
Posted by: hojo on Sunday, July 27 @ 10:13:01 MYT |
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| It works perfectly
Thank you for figuring this outPosted by: Paradroid on Sunday, July 27 @ 20:42:44 MYT |
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| hojo: you can use only 3 resistors, as shown by Howard who has kindly drawn the ascii schematic above.
reversing works because essentially, you just need to supply more than 1.2v to those 2 pins to enable them to start charging. Any voltage above 1.2v should work. More explanation is shown in my iPhone 3G charger page which can be accessed via the link at the bottom of the above post.
Apple has a pretty good reason for doing so. Although the charger is a bit more complicated, the charging is more efficient. because with the Linear Technology LTC 4066, the usb can supply the device with power as well as charge the battery instead of charging the battery only and with the device still drawing power from the battery. More is explained in the iPhone 3G charger post.
So yes, in a way we are forced to either buy their specialized chargers or build our own.Posted by: tzywen (http://tzywen.com) on Monday, July 28 @ 00:31:59 MYT |
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| Paradroid: No problem. glad it worked out for you ;)Posted by: tzywen (http://tzywen.com) on Monday, July 28 @ 00:32:42 MYT |
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| Heh!!.. This is wierd. I always thought the iPhone wouldn't charge because the USB stack on the phone side needed to switch up to 500mA to allow the phone to charge.. But it seems it's just a reference voltage it needs.. Did you notice any difference in the charging rate? Posted by: NTT (http://nttup.wordpress.com) on Monday, July 28 @ 07:28:09 MYT |
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| NTT: you are right about the usb stack having to request for the 500ma before the computer will provide it. The reference voltages are used as a form of override because the usb charging chip allows for it.
I have not measured the charging rates though.Posted by: tzywen (http://tzywen.com) on Monday, July 28 @ 18:05:35 MYT |
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| Hmm.. Because if the phone starts drawing 500mA even if the stack has not requested for 500mA, it's not a good design on Apple's part.. Looks like they are assuming that whichever device can provide these reference voltages is able to provide more than 500mA. Unless they "trickle" charge at 100mA.. Hence my question on charging rate..
Anyway, I was also thinking, what would happen if you connect the V+ and V- to a source which cannot deliver more than 100mA, but set the reference voltages to D+ and D- accordingly.. Esp when the battery is competely flat, will the iPhone come up in some "wierd" state?? Possible vulnerability?? :PPosted by: NTT (http://nttup.wordpress.com) on Monday, July 28 @ 21:21:28 MYT |
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| NTT: From what I've discovered, if the source (computer) cannot provide the 500ma, the iphone WILL NOT CHARGE. I have not tried limiting the source current to 100ma yet though, but it will be interesting to try it out ;)
Yea, I can see the headlines now: "Hacker unlock iphone using charger" lolPosted by: tzywen (http://tzywen.com) on Tuesday, July 29 @ 00:46:29 MYT |
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| | great article!
wondering if, since the components listed are all essentially passive, this design could be worked into an adapter that could be used with those USB chargers (such as yours) that don't supply the voltage on pins 2/3.
that is to say, something that is about 2" long with male/female usb connectors that could be plugged into any old usb charger to "magically" enable pins 2/3 for charging. Posted by: john on Tuesday, July 29 @ 01:24:02 MYT |
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| | oh, and by the way....
where did your battery meter come from?
looks cool. Posted by: john on Tuesday, July 29 @ 01:26:07 MYT |
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| | after careful reading of the 3G charger page, it occurred to me:
why not just make a cable that connects pins 1/2 and 3/4 on the female end, since the voltage to "trick" the chip on the motherboard only requires that the voltage be above 1.225 volts? Posted by: john on Tuesday, July 29 @ 01:36:05 MYT |
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| john: Thanks for the comments! Yes, you can make an adaptor to generate these reference voltages so a "normal" usb charger will be able to charge an iphone.
The battery meter is Aqwoah Battery version 1.2
Yes, it might work if you just connect the data lines to the +5v to trick the chip. But when I was designing this I was copying what the original iphone charger was doing. I didn't know about the chip's operation and I was merely emulating what the iphone's original charger was doing. The resistors I use are of fairly high values because I want to limit the current going to the data lines, in case something goes wrong. And since this design worked, I figured that I don't need to change it anymore. If you do try out your method, do let me know if it works because that would be a simpler method ;)Posted by: tzywen (http://tzywen.com) on Tuesday, July 29 @ 10:47:05 MYT |
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| | Thank you so very much for this helpful bit of information. I was able to see the D+ and - pins on the USB supplying some king of power (2.5 V on mine) and I didn't know how to duplicate that. Thank you for your drawing, but I was wondering if Howard's ASCii drawing could be explained a little further... do you simply connect pins 1, 2, 3, and 4 on the female USB to the places in between the resistors?
Once again, thank you all so much for this bit of help!
Robbie Mccarthy Posted by: Robbie McCarthy (http://asiab3.com) on Tuesday, July 29 @ 14:57:06 MYT |
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| Robbie: Glad it helped ;) Yes, you simply connect the pins 1,2,3,4 on the female usb to the places between the resistors, like so:
5v---|-----100k-----|----20k-----|----100k----|-----0v
PIN 1 PIN 2 PIN 3 PIN 4Posted by: tzywen (http://tzywen.com) on Tuesday, July 29 @ 23:50:53 MYT |
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| | Ok.... so I have mine wired exactly like that, but I'm wondering weather the resistors need to be a certain wattage.... the local Radio Shack only had 1/4 watt resistors. Are those some/any of my problems?
Robbie Posted by: Robbie McCarthy (http://asiab3.com) on Wednesday, July 30 @ 07:37:59 MYT |
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| | 1/4 watt resistors is more than enough to handle 5v @ 500mA. the math brings it to 0.0099999 Watt. Really small! If you have a local electronic supply (Radio Shack is NOT!) you can safely use 1/8 watt resistors, and those little puppies will fit in a tiny area! Thanks for the info all, and especially tzywen for getting this idea out there! Posted by: tech on Wednesday, July 30 @ 15:59:12 MYT |
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| Robbie: like what Tech said, 1/4 watt is more than enough so there's nothing to worry about ;)Posted by: tzywen (http://tzywen.com) on Wednesday, July 30 @ 21:58:37 MYT |
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| tech: thanks for the calculations. I'm assuming smds should be able to cope nicely too.Posted by: tzywen (http://tzywen.com) on Wednesday, July 30 @ 22:00:24 MYT |
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| For the ones who are not able (or too lazy ;) ) to make this, you can also use your iPod charger, it's way cheaper than the one for the iPhone but works perfect...
grtz (from Belgium :) )Posted by: Bram on Saturday, August 02 @ 00:19:55 MYT |
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| | Maybe this is a stupid question but do I have to use the 5V from pin 1 from the USB as 'input' for the voltage divider network? I see he uses 5V from the PSU to test it. I guess this is correct because for the car charger there isn't a PSU. Can anyone confirm this so I don't mess anything up :p Posted by: Jasper on Monday, August 04 @ 22:05:19 MYT |
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| Jasper: you can use any regulated 5v source. the 5v from the usb input is ok also.Posted by: tzywen (http://tzywen.com) on Tuesday, August 05 @ 07:24:46 MYT |
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| So do you think you could work this into a USB extension cable so that you could put that in line with your iphone charger whenever you want to plug it into a charger and then it would always work?
Also, would this interfear with syncing? I really want a way to plug my iphone into an always on USB port and not have to worry about turning off my computer over night.Posted by: JTWrenn on Friday, August 08 @ 15:32:15 MYT |
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| JTWrenn: This MIGHT interfere with syncing but I have not tried it yet. However, if the resistor values are large enough, maybe it won't.Posted by: tzywen (http://tzywen.com) on Friday, August 08 @ 18:54:42 MYT |
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| | Sounds like a good project:) hehe Posted by: JTWrenn on Saturday, August 09 @ 01:33:41 MYT |
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| JTWrenn: yea, and if you get results, do let me know. thanks!Posted by: tzywen (http://tzywen.com) on Saturday, August 09 @ 10:45:08 MYT |
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| | Has anyone come up with just a cable version of this. Basically a USB extension cable that converts a USB power source to be iPhone compatible? Posted by: Chris on Monday, August 11 @ 23:43:36 MYT |
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| I made 3 versions :
- in a USB car charger
- in a USB extension cable (no longer suitable for data)
- in an original dock cable (also no longer able to transport data )
then I ran out of resistors :p
The iPhone 3G slurps lots of electricity : when it's below 20% my laptop can't charge it anymore . I have to use the original AC adapterPosted by: Paradroid on Tuesday, August 12 @ 03:16:53 MYT |
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| I don't suppose there is a commercial version of the extension cable or dock cable is there?
=) Otherwise I would have to actually see if I can remember how to solder from my high school days.Posted by: Chris on Tuesday, August 12 @ 04:37:17 MYT |
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| howitee(@)hotmail(.)com
just too let you all know, i tried a new design works well on my 2g with my solar charger...
pin1--100k--pin2--5k--pin3--100k--pin4
three resistors 100k 5k 100k - connected in series between the pins.
I tried to connect pin 1,2&3 together but that did not work. Dunno why. However the design above works well for me and is very small. Email above, remove the brackets (they are to stop spam spiders and bots).
Love hugs, and FREE POWER!
Yay! Posted by: howard (http://www.hotmail.com) on Tuesday, August 12 @ 11:09:54 MYT |
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| I have one more idea that has not been tried...
pin1--100k--pin2--pin3--100k--pin4
That would give the same differential voltage in the middle, perhaps i didnt need the 5k resistor...
Have a go and let us all know!
HowardPosted by: howard on Tuesday, August 12 @ 11:13:49 MYT |
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| Howard: Thanks for sharing your design with us. Just curious, how long does it take to fully charge the 3G from a low battery state using the solar charger?Posted by: tzywen (http://tzywen.com) on Tuesday, August 12 @ 18:29:02 MYT |
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| Well that ruins my idea. I just want to be able to charge my phone when my computer is off and not have to think about switching between my sync connection and my charge connection. If you can't sync after the mod, then I am screwed.
I really hate that they made the phone that way.Posted by: JTWrenn on Wednesday, August 13 @ 10:13:37 MYT |
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| JTWrenn: you can make an elaborate switching circuit to switch over between data and charging modes. I think a 2 pole relay should do the job. Just an idea if you're really going to do it.Posted by: tzywen (http://tzywen.com) on Thursday, August 14 @ 18:08:46 MYT |
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| Why just don't use values of resistors from original iphone charger? :)
I make photo of original iPhone 2G charger PCB http://photofile.ru/photo/nnifty/95127169/100585644.jpg
And one more thing - iPhone is sensitive to charging voltage too, it must be between 5V and 5.9V. Original charger volage is 5.1V Posted by: Nifty (http://www.fixdev.com) on Thursday, August 21 @ 07:49:28 MYT |
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| nifty: Thanks for the photo! I didn't have the guts to open up the nice charger haha. Looks pretty complicated for a chargerPosted by: tzywen (http://tzywen.com) on Thursday, August 21 @ 22:04:02 MYT |
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| tzywen: Many thanks for posting this. And to the others who have added their comments. Good stuff.
For those who are contemplating this a few notes from my experience.
First, if you're going to build your own car iPhone 3g charger from scratch don't even think about using a linear regulator unless you can work a *big* heatsink into your design. I gutted an old car charger for the case and started with an LM317@5v with a small heatsink and it got way too hot to be used in a small enclosed plastic housing like the car charger case. I had to bust out a integrated switching regulator that I had. This is a bit of a bummer since if you aren't simply modding a USB car charger you'll end up spending $10-$15 for an ISR so it may be better buying an "incompatible" USB charger and modding it (although if you buy you're own ISR you know the quality and rated capacity).
Second, I really had to play around with the voltage dividers to get my phone to charge. People posted that they had success with two 170k resistors, or the ever popular 100k-20k-100k divider and taking all of the posts together it seemed like there is a bit of leeway. I had no such luck. I tried both the dual 170k and a 110k-20k-110k config and neither worked. I then tried 110k-30k-110k which worked (final volatges of 2.8 D- and 2.2 D+). So if it doesn't go the first time, keep trying.
Posted by: Joule on Friday, August 22 @ 07:51:51 MYT |
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| Joule: thanks for sharing with us your experience. A linear regulator such as the 7805 or lm317 should be able to handle the 500ma without a heatsink sicne they have internal thermal protection that limits output current when it gets too hot. But if you're concerned about the heat, then a switching regulator is the way to go.
As for the resistor values, there can be many combinations. Personally, I used the ones I posted in the above schematic and it works fine for the non-3g iphone.Posted by: tzywen (http://tzywen.com) on Friday, August 22 @ 23:59:32 MYT |
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| tzywen: I agree that a linear regulator can handle the load and it can limit output current to protect itself, it is just that I wouldn't recommend putting one in a cigarette lighter style car charger unless you are into burning plastic smells. :)
Given ~13v input voltage, 5v output voltage and a 500ma output current, the power dissapation would be (13 - 5) * 0.5 = 4 watts. The LM317 TO-220 package has a thermal resistance (junction to ambient w/o heatsink) of 50 C/W. So the temp above ambient of an LM317 w/o heatsink would be 4 * 50 = 200 C. Considering that there would be no air movement over the reg in a cigarette lighter style car charger case and that the plastic wouln't transfer heat very well I wouldn't want to drive around with that fireball in my car.
And I didn't mean to come across as sounding like I was saying the other resistor values didn't work. I'm sure they do. I just wanted to let people know that if a set of values doesn't work for them to not give up and keep tweaking.
Again, many thanks. This was a fun project!Posted by: Joule on Saturday, August 23 @ 00:30:51 MYT |
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| Joule: yes, it would become a fire hazard then at that temperature ;) As for the resistor values, I'm sure you didn't mean to say the others didn't work. And it's actually good if you can try out other combinations like you did because that would mean using resistors that you already have and saving a trip to the electronics store ;)Posted by: tzywen (http://tzywen.com) on Saturday, August 23 @ 10:26:19 MYT |
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| | does this work also for iPod touch? Posted by: pczou on Wednesday, September 03 @ 01:35:06 MYT |
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| Hi, i really appreaciate all the work you've done.
I have a 3g iphone and a 2G iphone car charger that connects to the radio (ie i used it to play music and to charge the iphone).
My question is: if i make what you did in this charger do you think it will still be possible to play the music?Posted by: cmv on Wednesday, September 03 @ 03:10:14 MYT |
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| I guess my question is almost the same as CMV's above.
I have a ipod dock in my car that connects to the stereo. It charges iPod Classic etc just fine. When I connect my iPhone 3G it still works (i can use the controls on my steering wheel to skip songs etc). It just wont charge. I can open up the dock pretty easy and have easy access to the pins. Only its on the dock connector side.
I found the pinout of the connector here:
http://pinouts.ru/PortableDevices/ipod_pinout.shtml
It all looks pretty straight forward. Only that site mentions the usage of only 10KOhm resistors for pin 25 and 27 (D- and D+), whereas you use 50KOhm. Which values should I choose?Posted by: Whacko on Wednesday, September 03 @ 09:14:41 MYT |
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| pczou: I have not tried it with an ipod touch yet. I assume it would work because the dock cables are the same.Posted by: tzywen (http://tzywen.com) on Wednesday, September 03 @ 13:36:51 MYT |
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| CMV: yes I think the music will still play because you're only messing with the D+ and D- pins. Whacko has posted the pinout page (http://pinouts.ru/PortableDevices/ipod_pinout.shtml) and you only need to put resistors on pin 25 and 27. Audio left and right is pin 3 and 4.Posted by: tzywen (http://tzywen.com) on Wednesday, September 03 @ 13:41:24 MYT |
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| Whacko: You can safely use the 10k ohms resistors as mentioned. Note that the connection is different that what I am showing here (pin 25 to 5v via 10k and pin 27 to ground via 10k).
However I have not tried this. The connection will not damage your device though because of the relatively small currents involved. Do let me know if it works out for you.Posted by: tzywen (http://tzywen.com) on Wednesday, September 03 @ 13:48:19 MYT |
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| | Thanks Tzywen, I will try it out and let you know how it goes. Posted by: Whacko on Wednesday, September 03 @ 18:49:26 MYT |
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| Thanks a lot for the answers...
I will try it this weekend....Posted by: cmv on Wednesday, September 03 @ 21:24:31 MYT |
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| | Hmm turns out the dock in my car uses the firewire pins. now I'll have to figure out how to make that work :P Posted by: Whacko on Wednesday, September 03 @ 21:58:43 MYT |
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| Whacko: I'm sure the dock have connection to pins 23,25,27,16 on the phone right? or someone will have to come out with a diy firewire charger ;)Posted by: tzywen (http://tzywen.com) on Wednesday, September 03 @ 22:47:55 MYT |
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| Tzywen, the pins are unused, so I can use them to solder the circuit to them.
This is what I'm going to do:
use the 12V from the firewire, and use a voltage regulator (7805) to step it down to 5V, then use your circuit with that 5V and I'm hoping that it will all work :)Posted by: Whacko on Thursday, September 04 @ 01:13:28 MYT |
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| Whacko: sounds like a perfect solution to me. someone mentioned that the voltage regulator may get very hot during use so you might want to consider where you put it. Let me know if it works out ;)Posted by: tzywen (http://tzywen.com) on Thursday, September 04 @ 01:50:40 MYT |
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| I ran into a nasty problem... I cant solder onto the pins of the ipod connector its too small and my wires won't connect. So I'm thinking of building a small circuit to replace the one in the dock entirely... but i'll have to find out how to do that first. and where to get a connector without cutting up a dock cable.
I did build the converter circuit (nothing difficult just the regulator before the 5v and GND) and seems to work fine when I test it with a power generator and my multimeter.
So my project is on hold for now. Maybe someone else has a simple solution.Posted by: Whacko on Thursday, September 04 @ 03:53:48 MYT |
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| Whacko: try using small gauge motor wires?Posted by: tzywen (http://tzywen.com) on Thursday, September 04 @ 14:26:46 MYT |
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| yeah I tried that, but the connector is actually surface mounted on the circuit. the pins are so close together I can't seem to solder it on without risking bridging two or more pins together.
But I found this site:
http://home.swipnet.se/ridax/connector.htm
they sell connectors, but also allow you to design a circuitboard. so thats what I'm gonna do, and just replace the existing board in my dock. (its nothing special, just a few resistors. Maybe I can integrate the 12v>5V powerconverter and your circuit to make it extra small.Posted by: Whacko on Thursday, September 04 @ 18:47:10 MYT |
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| Whacko: alright, good luck in whatever you're going to do!Posted by: tzywen (http://tzywen.com) on Saturday, September 06 @ 22:19:47 MYT |
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| The iPhone car charger at Monoprice works out of the box and costs $1.10 in the US. Just an FYI:
http://www.monoprice.com/products/product.asp?c_id=108&cp_id=10826&cs_id=1082602&p_id=3523&seq=1&format=2
I ordered a bunch then found your article and was worred I was going to have to modify them. Turns out they work fine.Posted by: Plex on Tuesday, September 09 @ 20:20:53 MYT |
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| Plex: thanks for the link. I went over to have a look and noticed that the charger is actually "Not for use with Iphone." Interestingly, if it charges, then it means that there is a reference voltage supplied which means it can be use for the iphone. Which makes me curious why they labelled it as "Not for use with Iphone."
Anyways, good find. If you open it up, do let me know what you find inside ;)Posted by: tzywen (http://tzywen.com) on Wednesday, September 10 @ 00:01:56 MYT |
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| http://dj4ar.com
thank u very mutchPosted by: برامج (http://n8mix.com) on Wednesday, September 17 @ 22:54:20 MYT |
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| I was wondering if you could post some visuals a little less complicated for us electronics noobs. I'm trying to adapt an old iPod 5G car dock for my iPhone. It uses the standard iPod connector wired straight to my car's electrical system and a audio line out signal straight to my radio. Of course it's wired to deliver 12v to the firewire pinouts for older ipods. Any help would be greatly appreciated.
http://www.pushingpixel.com/_temp/IMG_3117.jpgPosted by: kDawg on Friday, October 03 @ 02:08:17 MYT |
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| kDawg: can you verify that the car dock's connector has connections for usb charging? if yes, then you'll just need to identify the wires and connect the proper resistors to them. I don't have a a car dock so I don't know what connection they have with the iphone.
has anyone else tried this?Posted by: tzywen (http://tzywen.com) on Saturday, October 04 @ 01:25:23 MYT |
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| | Hi All, Great topic... I have a few FM transmitters but none work with my iPhone 2G, only ym iPods. They have the standard iPod connector and charge the iPhone but no audio is output on them, any idea on what I can do to make the iPhone understand it can output audio to it? BTW works great on my iPods. Posted by: MarkB on Wednesday, October 08 @ 03:12:12 MYT |
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| | I guess I need a resistor between ground and pin 21. What does it need to be to force audio to line out? Posted by: MarkB on Wednesday, October 08 @ 03:50:04 MYT |
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| It does not currently have power for USB charging. I thought I could rewire the 30 pin iPod connector to supply the correct voltage. Either starting from scratch or reporposing the supplied 12v down to 5v and so forth then to the corresponding pins on the connector. I assume #16, 23, 25 and 27 but I have to double check.
I can supply photos of the board when I get a chance. I've seen very few of these docks around but Iove mine. i don't understand why this company stopped making them. There is, however, a small ground loop problem but it's not terrible.
http://pinouts.ru/Devices/ipod_pinout.shtml Posted by: kDawg on Wednesday, October 08 @ 10:24:52 MYT |
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| Also note on the link supplied.
http://pinouts.ru/PortableDevices/ipod_pinout.shtml
It says...
To charge an iPhone 3G, usb data- (25) should be at 2v, usb data+(27) should be at 2.8v. This can be done with a few simple resistors: 33k to +5v (23) and 22k to gnd(16) to obtain 2v and 33k to +5v and 47k to gnd to obtain 2.8v. This is a "notification" to the iphone that it is connected to the external charger and may drain amps from the usb.
Would this combination work as well?Posted by: kDawg (http://http://pinouts.ru/PortableDevices/ipod_pinout.shtml) on Wednesday, October 08 @ 10:32:58 MYT |
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| For us noobs trying to understand resistor calculations. Here is the explanation :)
http://www.valvette.us/dcca03.htmlPosted by: kDawg on Wednesday, October 08 @ 11:44:03 MYT |
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| MarkB: there are pins for audio out but i'm not sure which pin will activate the audio output. looking at http://pinouts.ru/PortableDevices/ipod_pinout.shtml, pin 21 will determine the accessory type. might want to try the 1kohm to trick it into thinking it's on the dock because once it's on the dock, the audio output is enabled. hope that works.Posted by: tzywen (http://tzywen.com) on Wednesday, October 08 @ 21:45:11 MYT |
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| kDawg: thanks for the links! 16, 23, 25, 27 are correct. If you can supply 5v and the reference voltages to these pins, your iphone will start charging. make sure the connection to these pins are available on your dock though.Posted by: tzywen (http://tzywen.com) on Wednesday, October 08 @ 21:48:25 MYT |
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| | Wow all so complicated... I dont own an iPhone but i am curious about your invention of this charger... Cuz i am a Form5 Physics student too but i dont understand your diagram... Sorry for my noob-ness =.=
Did u learn all these by your own or it is in any syllabus? I am curious to noe! Posted by: Zell (http://onlybeyond.blogspot.com) on Thursday, October 09 @ 00:01:22 MYT |
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| | Do you think I could also step down the voltage from 12v to 5v. If so what would be the best way to accomplish this? I have access to all the pins on the iPod dock connector. Posted by: Anonymous on Thursday, October 09 @ 09:18:46 MYT |
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| Zell: Basically it's just a voltage divider network. I do research on my own time. There are lots of resources online for electronics stuff.Posted by: tzywen (http://tzywen.com) on Thursday, October 09 @ 17:18:07 MYT |
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| Anonymous: Good. you can step down the 12v to 5v using a 7805 voltage regulator. connection diagram: http://www.national.com/images/pf/LM78L05/00774408.jpgPosted by: tzywen (http://tzywen.com) on Thursday, October 09 @ 17:30:18 MYT |
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| Reading some other posts, I linked pin 11 to pin 15 in the plug and now the iPhone recognises the device as an audio device and outputs the audio just fine. Thanks for the help.Posted by: MarkB (http://www.scheduleit.co.uk) on Sunday, October 12 @ 20:36:15 MYT |
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| MarkB: great! thanks for sharing that info!Posted by: tzywen (http://tzywen.com) on Sunday, October 12 @ 22:55:28 MYT |
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| thanks,
this works for the ipod touch 1st genPosted by: lalala on Monday, October 13 @ 02:57:54 MYT |
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| lalala: you're welcome, glad it worked out for youPosted by: tzywen (http://tzywen.com) on Monday, October 13 @ 19:21:27 MYT |
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| Hi, I hava a CELLY Multi Travel Charger (usb), wich i want to modify as the diagram drawn by TZYWEN, for my Ipod touch
What I don't understand is...why can I charge my Ipod Touch with a Computer USB port without any problem.....does the USB port on a computer have 2.5v on pin 2 and 1.8 v on pin 3 ????
Thank's for your time.
Regard's
Richard
(The Netherlands)Posted by: Richard on Monday, October 27 @ 04:00:36 MYT |
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| Richard: Your ipod negotiates with the computer's usb port for power when it is first plugged in. If this negotiation for power is not successful, it will not charge. Try plugging in your ipod when you first turn on your computer. You'll notice that it will not charge until the operating system boots up.
By using the reference voltages of 2.5v and 1.8v respectively on the data pins, we're telling the ipod/iphone that it is plugged into a wall charger and that it can start charging right away.Posted by: tzywen (http://tzywen.com) on Monday, October 27 @ 12:34:56 MYT |
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| Hi Chen,
I took apart one of my cheapo car USB chargers and found that it had three spaces for resistors, which corresponded nicely to what Howard posted - the nice thing about this is that it's symmetrical, so I didn't even need to agonise over which resistors needed to go where :-)
In my junk box repository of highly useful spare components I found a couple of 150K and a 33K resistor (so the ratios are still similar enough) and it seems to work just fine.
Many thanks to everyone that's contributed on this!
Steve.Posted by: Steve Bennett (http://www.lancs.ac.uk/~steveb/) on Monday, November 10 @ 19:42:19 MYT |
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| Steve: great work! my junk in my junk box has also saved me countless trips to the electronics storePosted by: tzywen (http://tzywen.com) on Monday, November 10 @ 21:53:02 MYT |
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| Thank you for taking the time to design and share this with everyone.
I purchased the finest cheap AC/USB charger (less then $7Canadian) Made in China had to offer that claimed to charge ANY ipod or other USB powered device. Of course, once I got it home and plugged in my Ipod Nano (2nd generation) it gave it power, but that's it. No charging at all.
The multimeter quickly found only the +5 and GND pins were active, nothing on the two middle data pins.
I tried shorting the two data pins (suggested on another website), which brought up the charging screen, however, it would only say charging for a few minutes, then the Ipod would shut off and no charging would take place.
I found your article here, and figured, for $7, even if I blow it up it's worth a shot.
I built the simple voltage divider, and have charged both my wife's and my Ipod Nano's.
It works great!
Thanks again!Posted by: Aaron (http://www.JaggedPath.com) on Tuesday, November 18 @ 22:44:21 MYT |
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| Aaron: Glad it worked out for you ;)Posted by: tzywen (http://tzywen.com) on Wednesday, November 19 @ 18:59:12 MYT |
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| dear How are u?nice to contact u.this is Maple from Thanko Global Technology Co.，Ltd.we specialized for extending fashion computer peripheral products, electronic products.We develop competitive new projects based on marketing research.so our products are salable in USA,England,Polan and so on.we are the best manufacture that you can trust in China. if you'd likd to know more detailed information about some specific products,pls feel free to let me konw. i think if you can tell me what kind that you are interesting in,there will be better,tks. i am looking forward to see your reply! best wishes! www.thanko.cnPosted by: maple (http://www.thanko.cn) on Thursday, November 27 @ 16:54:11 MYT |
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| I worked for 2 days alone, try to figure out how to configurate the data pins on car / usb charger, to make it workable for iphone, then I find this place, thanks tzywen for your great job! will try later.
I have a strange problem, I bought a cable (which may be suitable for ipod only), when I plug it into an ASUS mother board computer, it can charge 3G iphone but display error msg for data transfering; when I plug it in another computer, no charging at all. the only different as I know is the USB on ASUS is coming with grounded shield (5th wire), another one doesn't. I am not sure if you guys have such problem before.
FYI, there is nothing wrong when I use the original cable on both computers. Posted by: vantry on Saturday, December 20 @ 03:07:39 MYT |
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| vantry: glad that you've found this useful!
Very strange problem you have there. If the original cable works, then there must be something wrong with your other cable. have you checked the pins with the original cable?Posted by: tzywen (http://tzywen.com) on Saturday, December 20 @ 11:06:20 MYT |
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| | Hi there, I'm quite new to electronics but have produced the circuit as above and am not having so much success.. The iphone starts charging then after about 30 sec /1 min it stops. I'm using a 7805 to regulate a 9v battery to 5v. The iphone comes up with the charging icon and then turns into the charged sign even though the iphone isn't charged?? Any ideas anyone????
Pre thanks! Posted by: tuner on Sunday, December 21 @ 21:18:50 MYT |
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| tuner: can you verify that the 7805 is giving out 5v?Posted by: tzywen (http://tzywen.com) on Sunday, December 21 @ 23:42:01 MYT |
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| | Hey Tzywen, Yep 7805 giving out 5.04v. That's enough right? I can't work it out - feel like I'm losing it.... Any ideas? Weird huh. Thanks for replying so quickly! Rob
Posted by: tuner on Monday, December 22 @ 09:28:14 MYT |
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| tuner: 5.04V is enough. How about your resistor values? What values are you using? I can't really be sure by looking at the photo. Can you confirm that the data pins are getting the proper voltages?Posted by: tzywen (http://tzywen.com) on Tuesday, December 23 @ 01:06:49 MYT |
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| Hi Tzywen, I followed your recipe, everything is prefect, and now it is working like a charm! thanks a lot!!!
Posted by: vantry on Tuesday, December 23 @ 08:02:32 MYT |
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| 1st of all: Great info, thanks for that everyone.
My home situation: 4 penlight batteries delivering 5,4 volts full and 4,7 when empty. 1900mAh. Charged by a small solar panel, though a diode.
Obective: Charge my 3G iPhone. I plan to emulate 2,3V on D+ en 2,95V on D- because that is what comes out of my charger.
So I could use:
5V --- 100K --- 2,96V --- 30K --- 2,35V --- 115K --- 0V
But I could also be using:
5V --- 200K --- 2,96V --- 60K --- 2,35V --- 230K --- 0V
Or:
5V --- 50K --- 3V --- 15K --- 2,4V --- 60K --- 0V
Would anyone be able to advise/explain what would be the difference between these? My gut feeling says it will effect the speed of drainage of the batteries. And if I would go to extremes it would not work, but how does it affect the charging process? So I may take the most efficient decision...
I do plan to include a charge on/off switch, cause it doesn't seem right to me to leave the batteries short-wired over 250k ohm while they are not charging the phone. Or is that a misunderstanding?
Also I fear that this scheme will reduce the mAh of my batteries, since the whole idea of the resistors is to let x% be distributed across a resistor straight to the ground...
Thanks for the advice. Regards.Posted by: Thomas (http://www.duurzaamnu.nl) on Monday, January 05 @ 22:46:42 MYT |
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| Thomas: The difference between those resistor combinations is the current flow through them. Assuming that 5v is applied to each of those, the resistors alone will draw 0.02mA, 0.01mA, and 0.04mA respectively. These currents are so small that they're negligible so any of those combinations should work. But I will recommend you go for the 50k,15k and 60k combination because that will give a more stable voltage to the data pins.
You don't need a charge on off switch because the batteries are not directly connected to the + and -. So yes, that is a misunderstanding.
Again, not to worry too much about the resistors as they don't really consume that much power from your batteries. Unless you're talking about ohms, instead of kohms.
Do let us know if it works for you ;)Posted by: tzywen (http://tzywen.com) on Wednesday, January 07 @ 16:34:39 MYT |
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| Hi Tzywen,
Thanks for the advice. I did just so. And it seemed to work! Any time I connect "my project" to my iPhone 3G, it goes bleep! and shows the charging battery.
You can see pictures and scheme here:
http://www.duurzaamnu.nl/archives/47-iPhone-3G-oplader-op-zonnenergie.html
(switch to English in the left margin).
But...
The battery does not get any fuller! (I did only one single test sofar). What a pitty. Even after several hours, it still said it was charging, but in fact the battery indicator had reduced by 1 bar!
Probably the AA batteries are too weak. I measured a voltage of 4,4 volt at the end of that one run.
Oh, and today there was no sun, so we're still flat.Posted by: Thomas (http://www.duurzaamnu.nl) on Tuesday, January 13 @ 00:20:31 MYT |
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| Thomas: A higher voltage should solve your charging problems. A bigger solar cell maybe? Or you can test with a 5v source first to make sure it's working. Good luck!Posted by: tzywen (http://tzywen.com) on Wednesday, January 14 @ 17:12:56 MYT |
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| Hi! Thanks for all the info you posed!!
I used an eq circuit with a ac/dc transformer with an output of 5.1V but when i measured with my miltimeter it read 7.6V so I used an L7805CV voltage regulator to get the desired 5V. My circuit is as follows:
7.6V --- L7805CV --- 5V --- 100k --- 2.5V --- 27k --- ~1.8V --- 67k ---0V
But i have a peculiar issue with it. When i connect it to my ipod touch the charging icon appears so i get excited! Then after about 30 seconds it changes to the fully charged icon and then it almost fully DISCHARGED my battery!! Not instantaneous obviusly but it discharged at a higher rate than when not connected!!
My charger specs these
Input: 120V
Output: 5.1V / 500mAh
Please tell me if i´m doing something wrong
Thanks!Posted by: Mario on Tuesday, January 20 @ 08:09:53 MYT |
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| Mario: I think your input voltage is insufficient. Your ac/dc converter is giving higher voltage readout because it's not on load. but when you connect it to the 7805 and the iphone, the voltage will drop too much to provide sufficient current for charging. I would recommend you measure the voltage going to the iPhone. If it's below 5v, get rid of the 7805.
BUT FIRST make very sure that the charger is indeed giving out 5.1v on load by connecting a 100ohm resistor across it and measuring the voltage across the resistor.Posted by: tzywen (http://tzywen.com) on Tuesday, January 20 @ 17:41:48 MYT |
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| now a days i'm trying to charge my new ipod touch 2 with none ipod charger by simply supply it with 5v volage, but turns out not work,
finally find this thread and thanks everyone, with four resister to divide voltage
V+ D- D+ GND
V+ 5V
D- 2.5V
D+ 2.0V
GND 0V
three 104（100k）one 154（150K）i take it from old Floppy disk driver
before this i only use one 100k resister to upconnect D- to 5V, it still work
i'm afried to destroy my touch, decide to do the normal way
here is a guy open the genuine ipod charger, and draw the circuit
http://zone.it.sohu.com/forums/thread-2067473-1-1.html Posted by: limax on Friday, January 23 @ 15:16:35 MYT |
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| | Of all the DIY guides, I finally found exactly what I was looking for with the information here. I wanted to install a USB port in my car specifically for my iPhone, mainly because I just don't like having the car charger be just one more item I need to make sure I have with me -- I already take the USB cord wherever I go.
Anyway, this works, although I didn't follow the original guide. Instead, I used a 7805 regulater to supply the base 5v.
Here's how I wired the USB port:
(V+) ----- 100K ----- (D+) ----- 10K ----- (D-) ----- 100K ----- (V-)
Now the problem...I haven't left my iPhone charging for more than maybe 5-10 minutes because it starts to get warm. I'm no electrician, but I'm sure this isn't good. The output voltage to the data pins are 2.5V and 2.3V. Perhaps this is too much? What resister value should I use to lower these voltages and where would I insert the resistor(s) in the circuit?
Thanks. If it weren't for this guide, I wouldn't have gotten this far. Posted by: Marc (http://myspace.com/majicconcepts) on Wednesday, February 04 @ 09:24:04 MYT |
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| Marc: your connection seems to be correct and your iPhone heating up could be due to the charging. But just in case, double check your connections and make sure you're supplying a 5v to the iPhone.
some people had success with this configuration:
(V+) ----- 100K ----- (D+) ----- 20K ----- (D-) ----- 100K ----- (V-)
Do let me know how it goes.Posted by: tzywen (http://tzywen.com) on Wednesday, February 04 @ 20:11:20 MYT |
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| | tzywen: Thanks. I guess I'm going to have to wait until this weekend to update my configuration. I don't have any 20K resistors, but will connecting another 10K resistor in series to the existing 10K resistor be the same thing as having a 20K resistor there?
Also, what's the word on supplying current to just ONE of the data pins.
Seeing as how maybe the heating might be a result of the voltage going through the data pins, perhaps it would be prudent to install a switch to kill power to them after the iPhone begins charging? Posted by: Marc on Wednesday, February 04 @ 23:52:33 MYT |
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| | Also, if it's worth mentioning, the voltage going into the iPhone with my current configuration is 5.1-5.3V. Could this also be related to the heating? Posted by: Marc on Wednesday, February 04 @ 23:56:40 MYT |
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| Marc: I'm currently using the configuration that you see on the very first photo of this post. and yes, it does get warm but not hot and it charges the iPhone fully.
yes, 2 10k in series will give you 20k
some people have reported success with just voltage to one of the pins. I have not tried it so I can't comment much. Heating is probably not caused by the voltages going to the pins. If you try charging the iPhone with the wall charger you'll notice that it gets warm also.
5.1-5.3v is within limits so it shouldnt be a problem.Posted by: tzywen (http://tzywen.com) on Thursday, February 05 @ 18:16:20 MYT |
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| | tzywen: Ah, thanks for that info. I never noticed it getting warm when charging from the wall. I spent some time last night trying to come up with a circuit similar to yours, and I hope to be able to test it out tomorrow if not this weekend.
All the resistors are 100K ones. According to my readings last night, I will get 1.6-1.7V to D+ and 2.5V to D-. I wish I was able to test it out on my phone, but my one and only free female USB port is installed in my dash.
I'll post my results here.
Also, have you noticed problems when syncing your iPhone after doing this (e.g. syncing "freezes" iTunes)? Posted by: Marc on Thursday, February 05 @ 23:03:24 MYT |
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| Marc: thanks for the diagram. looks good, but I'm skeptical about the 1.6-1.7v for D+. Not sure if that will be enough to trigger it to charge.
Anyways, will be waiting to hear your results! ;)
No, I have not had any problems with freezing iTunes. have you got the latest itunes and proper usb drivers?Posted by: tzywen (http://tzywen.com) on Thursday, February 05 @ 23:47:48 MYT |
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| | tzywen: well, according to the specs in your post, I only need 1.25V, so it'll be worth a shot. At worst, I'll just have to try another configuration. I'm only working with what I have on-hand, but if this configuration fails, I'm going to make one EXACTLY like yours (lol).
As for the freezes, well, it started only after that last time I tried charging my iPhone with the USB port in my car. It's ok. I might just take advantage of my Apple Care Plan and have it replaced. Posted by: Marc on Friday, February 06 @ 13:41:10 MYT |
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| Marc: When the iphone draws current from those pins, the voltage may plunge below 1.25v. anyways, am interested in your results ;)Posted by: tzywen (http://tzywen.com) on Friday, February 06 @ 18:08:14 MYT |
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| I used for all resistors 100K ones. D+ and D- are on the same potential.
The iPod Touch 1G is loading.Posted by: MoD on Monday, February 16 @ 18:22:33 MYT |
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| stop all the guesswork!!
From http://pinouts.ru/Devices/ipod_pinout.shtml
To charge an iPhone 3G / iPod Touch 2nd gen, usb data- should be at 2.8v, usb data+ should be at 2.0v. This can be done with a few simple resistors: 33k to +5v and 22k to gnd to obtain 2v and 33k to +5v and 47k to gnd to obtain 2.8v. Posted by: Docpaul on Saturday, March 14 @ 16:48:30 MYT |
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| is this charger compatible with the ipod calssic 5.5G?
thx guysPosted by: jordan on Monday, March 16 @ 07:57:20 MYT |
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| Hi tzywen,
It turns out my original configuration as well as a few of the others all worked as long as the reference voltages were above the minimum requirements (http://tzywen.com/modules.php?name=News&file=article&sid=696); however, I wouldn't recommend letting the voltages get above 5V, of course. I was using my all-100K-resistor set-up until I ended up breaking the USB port itself.
I couldn't find the comment, but someone posted a link to a cheap USB charger (under $2USD, I believe) that I also ordered. For those not inclined to perform this mod yourself, it does indeed work for the iPhone 3G. My brother uses it his car since he didn't want let me "mess with" his car's wiring.Posted by: Marc (http://marcswall.wordpress.com) on Saturday, March 21 @ 15:15:43 MYT |
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| Marc: thanks for the feedback! The original iPhone charger outputs 5.11v, 2.605v, 3.203v, and 0v with respect to ground.
Of course, a ready built charger will save you from having to experiment and having fun ;)Posted by: tzywen (http://tzywen.com) on Saturday, March 21 @ 16:53:04 MYT |
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| if it works for the ipod touch i am going to look into doing thisPosted by: Internet Marketing (http://jordansguide.com) on Sunday, March 29 @ 10:50:49 MYT |
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| | great ideas, converted a £1 usb car charger to a ipod nano charger with 2 180kohm resistors from the +-5 pins to the centre 2. gave +5, +2.6, +2.6 and 0v on the four pins. works great. Posted by: Andy on Thursday, April 02 @ 03:57:40 MYT |
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| OMG........... u're so smart.. i can never do that... i am so bodo but i found your blog educational. thanks for infoPosted by: Shireen K (http://shiryen.blogspot.com) on Sunday, April 05 @ 16:37:50 MYT |
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| Shireen: you can always buy a premade one. I'm sure china is exporting them by the millions ;)Posted by: tzywen (http://tzywen.com) on Monday, April 06 @ 18:36:39 MYT |
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| I have sucsessfuly made a charger out of 6 AA rechargable batteries (each battery 1.2v) that works on the ipod touch 1G (maybe others).
1.)hook up the + and - of a usb female connector to the + and - of the battery pack
2.)cross D- and D+ wires (green and white) on the female connector
3.)plug in a sync cable
4.)plug in your ipod (Iphone?)
5.)CHARGING
what i want to know is if this will work with normal non-rechargeable batteries.
PS the batteries were fully charged and had a total of 8000 mah, 7.2 volts
this is also posted here: http://www.tzywen.com/modules.php?name=News&file=article&sid=696Posted by: Jordan on Saturday, April 25 @ 21:56:06 MYT |
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| Jordan: yes, it will probably work with non rechargeable batteries as long as the voltage is kept at 5 volts or slightly above it. Not too high or you may burn the ipod/iphonePosted by: tzywen (http://tzywen.com) on Sunday, April 26 @ 18:43:49 MYT |
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| | Maybe somebody can help me out. I had an old sprint charger that has an output of 5.15v. I figured I'd splice it with a cut USB cable to make a car charger, but it's not working at all for me. I've checked and rechecked that I have the right voltages. Power is 5.15v, white wire is 2.75v, and green wire is 2.02v. When I plug in my phone, nothing happens. Any ideas? Posted by: Josh on Saturday, May 16 @ 04:40:33 MYT |
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| Josh: what resistor values are you using? can you confirm that when the iphone is plugged in, the voltages are still around those values that you have mentioned?Posted by: tzywen (http://tzywen.com) on Sunday, May 17 @ 21:42:37 MYT |
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| | Same resistor values as above. 2-50k a 100k and a 150k. I can confirm the voltage when the phone is plugged in. Only thing I could think of was that maybe the old sprint charger didn't let enough current through. Maybe? Posted by: Josh on Monday, May 18 @ 00:17:50 MYT |
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| Josh: not letting enough current through could be the problem. But do double check your circuit and make sure the grounds are properly connected. Alternatively, try a different 5v source.Posted by: tzywen (http://tzywen.com) on Monday, May 18 @ 20:41:25 MYT |
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| | Could someone put together a compatibility list for this schematic(including older generations of other iPods). Thanks, it would be very useful PS why does everybody say it will mess up your iPhone or iPod if you have a voltage higher than 5v when or the back of my touch it says 5-32v? Posted by: Jordan on Tuesday, May 19 @ 11:14:10 MYT |
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| Jordan: the LTC4066 which is the power controller chip responsible for charging your iphone's battery can only handle a maximum of 7volts. So it is advisable to keep voltages as near to 5volts as possible, to avoid damaging your iphone.Posted by: tzywen (http://tzywen.com) on Wednesday, May 20 @ 23:17:20 MYT |
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| I've build a small adapter to power the iphone on the motorbike using an 7805, but as mentioned in previous posts, even with a heatsink, the 7805 becomes really hot. Is there a way with the resistor values to let the iphone think it can only charge at eg 100 mA?
The 7805 now starts at 800 mA charging the iphone when this is at approx 50% battery. This drops to approx 500 mA when the iphone gets more and more charged.Posted by: gedp on Thursday, May 21 @ 06:16:08 MYT |
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| gedp: the 7805 has a thermal protection built-in. once it becomes too hot, the output current will be limited to 500ma. putting a heatsink on it should solve the problem.Posted by: tzywen (http://tzywen.com) on Thursday, May 21 @ 11:47:00 MYT |
|
|
USB boxes 4 AA batteries with USB out
http://myworld.ebay.com.au/prefect_spares/
ebayer prefect_sapres in AUSTRALIA is selling these:
USB boxes 4 AA batteries with USB out
and references this page.
CFYI
Doug.Posted by: Doug (http://members.westnet.com.au/prefect/usb_box.jpg) on Thursday, May 21 @ 23:37:11 MYT |
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| Doug: thanks for the tip. The enclosure can be used to make an inexpensive portable charger for those long trips.Posted by: tzywen (http://tzywen.com) on Friday, May 22 @ 15:11:22 MYT |
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| | I built charger with 6 xAA and regulated it to 5v (volt meter said 4.94), I used the two resistor method with two 150k resistors. For an hour or so it charged corectly then it said it was full but then when I in un-plugged the batt pack it said it was at 10%. So then I plugged the charger back in and it still was not charging my iPod touch. Gnd D- 2.28v D+ 2.28v + 5v Posted by: Anonymous on Saturday, May 23 @ 20:25:49 MYT |
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| Anon: you have to make sure that the battery pack can supply the required current. Also when the 7805 (I assume you're using this to regulate to 5v) gets hot, it cuts down the current output. If you're using a well regulated supply that can deliver enough current (around 500ma), it should charge your ipod touch to full.Posted by: tzywen (http://tzywen.com) on Monday, May 25 @ 19:50:02 MYT |
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| | Could some one help me make a 4x AA non-rechargable battery pack for the iPhone. If I use 4 Nonrechargeable each at 1.69v it equals around 6.19v and when I plug it in to my iPhone it won't charge even with the corect voltages on pin 2-3. I thought the charging chip inside could handle up to 7v Posted by: Jordan on Friday, May 29 @ 03:12:28 MYT |
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| Jordan: I won't recommend feeding more than 5.2 volts to the iPhone. You can use a boost converter if you plan on using less batteries. Try google "minty boost"Posted by: tzywen (http://tzywen.com) on Friday, May 29 @ 13:22:08 MYT |
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| i am looking for a 5V .5 to 1A switching voltage regulator for a iphone battery pack because a linear one like the LM7805 gets to hot.
thanks
Posted by: jordan on Saturday, May 30 @ 10:36:25 MYT |
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| jordan: yes, that's the right way to go, as efficiency is better with a switching voltage regulatorPosted by: tzywen (http://tzywen.com) on Saturday, May 30 @ 14:25:35 MYT |
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| | can anyone recomend what switching regulator i should use? Posted by: jordan on Sunday, May 31 @ 09:26:31 MYT |
|
| srry about the extra post
will this work for the 5V 1A switching voltage regulator:
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=1992540&Posted by: jordan on Sunday, May 31 @ 10:00:21 MYT |
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| jordan: you can follow the boost circuit from the minty boost here: http://www.ladyada.net/make/mintyboost/parts.htmlPosted by: tzywen (http://tzywen.com) on Sunday, May 31 @ 16:04:45 MYT |
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| It works in my iphone 3g Thank you your doing good hope you can share more! :) thanks Posted by: Jegard (http://frex_318@yahoo.com) on Friday, June 05 @ 04:07:26 MYT |
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| hi, i need to buy a charger for my canon camcorder which i've replaced 3 times but keeps having the same defect. where can i buy a cheap multipurpose charger with output of 8.4V, 0.6A.
Sorry I'm not student of electrical eng and dun know much abt electric.
An original charger will cost rm285! I'm also contemplating on the solar multipurpose charger but it's also almost rm200! where is the best place to source for these kinda stuff?
One more thing, if the current is more than 0.6A, would it damage my battery being charged? Posted by: law (http:// leezrt@yahoo.com) on Thursday, June 25 @ 17:16:33 MYT |
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| | Hi everybody
I just want to say thank you for this great information. I modified my iPhone connector (which had only 12V Firewire power) to 5 volts with a voltage regulator (78S05 -> becomes very hot!) and added 3 resistors to charge my iPhone 2G & 3G. As it was no room for the resistors inside the plug, I placed them outside in a heat shrink tube.
Here is my config: 5V -- 56k -- pin25 (2.9v) -- 22k -- pin27 (2.1v) -- 56k -- GND
Posted by: Attila on Saturday, June 27 @ 18:30:55 MYT |
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| Attila: the 7805 does get very hot because you're regulating it from 12volts. Keep it heatsinked and that should keep the temperature down. Anyways, the 7805 has internal thermal protection so don't worry about frying it.Posted by: tzywen (http://tzywen.com) on Sunday, June 28 @ 12:43:11 MYT |
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| I did some tests and thought i would share the results, my problem was more the output voltage range acceptable for the iPhone.
Anyone have an idea of what happens when you operate at the out limits of the voltage range for an extended time? Or any other resources or links for iPhone chargers?
Ipod Touch version: 2.2.1
(V) (mA) P (VI) Comment
5.9 0
5.8 0
5.7 0
5.6 0
5.5 0 iPod plug symbol and charge symbol alternating
5.4 507 2.7378
5.3 507 2.6871
5.2 510 2.652
5.1 510 2.601
5 520 2.6
4.9 500 2.45
4.8 449 2.1552
4.7 390 1.833
4.6 305 1.403
4.5 225 1.0125
4.4 100 0.44 iPod plug symbol and charge symbol alternating
4.3 0
4.2 0 Posted by: dancanada on Wednesday, July 08 @ 01:29:19 MYT |
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| dancanada: thanks very much for sharing your findings! A stable power supply is important to charge the iPhone because sometimes when I'm using supplies that are not so regulated, it charges for a while then it doesn't charge anymore. Around 5.1v should be acceptable and I wouldn't recommend going too high because you might fry the electronics inside.Posted by: tzywen (http://tzywen.com) on Wednesday, July 08 @ 01:44:39 MYT |
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| | I didn't want to try 12 V thats for sure, someone on another site said he bricked a friends iphone by using an older charger. I didn't think that it would since the firewire power is on 2 of the other 30 pins, but that type of research someone else can do. (i am guessing some chargers get solder bridges in all weird places on the 30 pin connector) Posted by: dancanada on Wednesday, July 08 @ 03:02:26 MYT |
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| dancanada: yes, frying the charging circuit is a sure way to brick your phone since there's no way to charge the phone anymore. According to the LTC4066 datasheet, the absolute maximum input is 7v. An older charger with firewire will give 12v.Posted by: tzywen (http://tzywen.com) on Wednesday, July 08 @ 13:15:50 MYT |
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| | tzywen: I have read all the posts above but I am not sure how to proceed :) I own an iPhone 3GS and have Graffin Simplifi charging base http://www.griffintechnology.com/products/simplifi. The unit comes with an AC adaptor that only powers up the USB outlets behind but does not charge the iPhone. The only way to charge the iPhone is by using their USB cable (USB A to Mini) and plugging it into a powered ON computer. I was wondering if I can use your hack to modify the USB cable and instead of plugging into a computer plug it in the Apple's wall charge instead to make it work. I understand that I will loose the transfer capability from that cable. The alternative method can be to use the Simplifi supplied AC adaptor (output 5.0V 1.5A), add resistors and connect it to the USB in that runs to iPhone however I am not sure how will that affect if I have a USB running for transferring data/charging via computer and another power input to charge the iPhone. I guess I should not be using both at the same time. I have probably went too far here, just trying to find the simplest way to charge my iPhone using a USB cable.
Posted by: Hasham on Wednesday, July 15 @ 11:41:10 MYT |
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| Hasham:
The only way to charge the iPhone is by using their USB cable (USB A to Mini) and plugging it into a powered ON computer. I was wondering if I can use your hack to modify the USB cable and instead of plugging into a computer plug it in the Apple's wall charge instead to make it work. I understand that I will loose the transfer capability from that cable.
You can simply plug their USB cable into the Apple wall charger and it should charge the iPhone. Yes, you will loose transfer capability.
The alternative method can be to use the Simplifi supplied AC adaptor (output 5.0V 1.5A), add resistors and connect it to the USB in that runs to iPhone however I am not sure how will that affect if I have a USB running for transferring data/charging via computer and another power input to charge the iPhone. I guess I should not be using both at the same time.
Yes you are right. If you go with this method, you won't be able to transfer data while you are charging. So the best way is to plug the USB port into a computer when it is turned on and switch over to a wall plug when you turn off your computer. I know it's a hassle but there is no device that I know of that can do the switchover automatically for now.
Also can this be used http://www.iogear.com/product/GMPT047AI/ with Apple's 3GS ac adapter and then plugged into a USB A to mini cable running into Simplifi without the need of adding any resistors?
Yes, this can be used provided you use it only with Apple's chargers, since their chargers already have resistors inside.Posted by: tzywen (http://tzywen.com) on Wednesday, July 15 @ 14:19:58 MYT |
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| | tzywen: Thats what I thought too but it doesnt quite work as it should. I will upload some pictures for better understanding. Posted by: Hasham on Wednesday, July 15 @ 23:04:53 MYT |
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| | tzywen: Can't find the camera lol... anyways so the thing that confused me the most was the inability to charge the phone using Apple's ac adapter. The supplied USB A-Mini cable when plugged in the base (Simplifi) and to a computer syncs and charges the phone just fine but when I plug the same USB cable to a Apple's ac charger it doesn't do anything. The little blue light on the base however lights up but the phone doesnt charge or show any sign to connectivity. If I understood it correctly the Apple's ac adaptor has the resistors and does the D+/- thing so there shouldn't be any modification need to the cable, right? I have a 5V ~550mA ac adaptor from my motorola that has a mini USB plug. Wonder if I can plug that in directly to the base :P Posted by: Hasham on Thursday, July 16 @ 01:40:37 MYT |
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| I tried the schema with 2x100 and 1x20K Ohm, but it seems that it does not work for my iphone 3GS.
Does anyone know a working schema for the 3GS?
The voltages i get:
pin1: 5.4V; pin2 2.9V; pin3 2.4V, pin 4 0VPosted by: promy on Thursday, July 16 @ 05:06:30 MYT |
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| Hasham: I think the dock probably have extra circuitry that prevented that from working. I'm not vey sure unless I can see the disassembled dock haha. That might explain why the resistors didn't work on the dock. But when it is plugged to the computer the iPhone probably recognized that it is connected to a computer and it will start charging automatically, without the resistors.Posted by: tzywen (http://tzywen.com) on Friday, July 17 @ 17:07:52 MYT |
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| promy: can you verify that the supply is capable of delivering at least 500ma? Also sometimes "dirty" supplies can cause the iPhone not to charge. For now I don't have a 3gs for testing yet.Posted by: tzywen (http://tzywen.com) on Friday, July 17 @ 17:10:00 MYT |
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| More people need to open up commercial chargers and find out the official resistor values:
If D+ and D- are both 75K over 50K, there are 2 V on each, and the supply can do 500 mA
If D+ is 75K over 50K and D- is 43K over 50K, the voltages are 2 V and 2.66 V, which is a 1 A supply.
Open up your recharger and look at the SMT resistors or just use a multimeter measuring between each pin to deduce the voltages and resistor values from outside.Posted by: Steve on Wednesday, July 29 @ 11:02:28 MYT |
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| tzywen, JUST IN TIME!! I've been looking for this mod and it was frustratingly absent from the internet. I obviously don't want a car charger in the socket (looks bad, keeps other stuff from using it), and the carcharger/radio combo's have awful sound quality. The great thing is that you can hide this component, and make a dock with USB and audio, and route the power to the fusebox. Does anyone know if this will cause a ground loop if I RCA from dock to my amp with the usb charge also? That's my only fear and the one I don't fully understand . I'd also like to put a charging switch to keep things not constantly charging. BTW, pin 21 of ipod dock connector is for accessory action, and can act like belkin charger with 1Mohm resistor... see http://nuxx.net/wiki/iPod_Dock_Connector
Thanks!Posted by: willPS (http://nuxx.net/wiki/iPod_Dock_Connector) on Monday, August 10 @ 09:35:15 MYT |
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| willPS: Mine did not cause a ground loop when I used my iPhone to play music through the headunit when it was charging. Instead of putting a charging switch, you can just wire the charger such that it charges only when the ignition is put to on. There's no harm in continually charging your iPhone.
And thanks for the tip for pin21!Posted by: tzywen (http://tzywen.com) on Tuesday, August 11 @ 07:48:48 MYT |
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| before anything, i would like to thank you for this charger circuit. It really works, but there is a problem.when charging and playing there a noise coming out of the ipod, specially when the display light is on.
I also tried to make a circuit and make used of this chager using wall adapter inside th house but still the same. I can still here the noise while charging.
Please help me.Posted by: poohjangnim on Tuesday, September 01 @ 16:37:55 MYT |
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| oH i forgot, I used the pin 1-gnd, pin2 -gnd, pin 3 left out, pin4 - right out. I used those pins to come up with the ipod dock. but the problem is the noise coming from the ipod. I tried using ferrite beads and capacitor on grounding system but still I can hear the noise.
Please help..........I will worship you if you could tell the solution.Posted by: poohjangnim on Tuesday, September 01 @ 16:50:03 MYT |
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| poohjangnim: can you describe the noise? is it a low humming noise? can you post your circuit diagram or a photo of your setup? I hope the noise is coming from the earphones and not the ipod itself.Posted by: tzywen (http://tzywen.com) on Tuesday, September 01 @ 20:26:00 MYT |
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| Hey,
I just measured the voltage on the Data(-) and Data(+) Pin of my Iphone 3GS dock cable and measured two times 0V. Coult it perhaps be that they changed it with the 3GS because i heared that also the extern batterys on ebay partially don't work with the 3GS anymore. And above there was the same thing reported. Does somebody have an explanation?Posted by: Tobsel on Wednesday, September 09 @ 02:17:05 MYT |
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| | Sorry, I made a mistake. I measured again and now Data(+) is at 2.06V and Data(-) is at 2.76V, so quite similar to the values above. I will try to bild up an adaptor for an battery supply the next days and will report you the results. Posted by: Tobsel on Wednesday, September 09 @ 03:43:14 MYT |
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| | What is the minimum input voltage for the 7805? Posted by: Tobsel on Wednesday, September 09 @ 05:02:35 MYT |
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| Tobsel: thanks for the feedback. The min input for 7805 is about 7voltsPosted by: tzywen (http://tzywen.com) on Wednesday, September 09 @ 18:49:28 MYT |
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| I built up the adaptor today (same voltage devider as above for D+, 50k and 40k for D-) and it works perfectly, except the fact that the 7805 gets very hot at 12V input so that I tested it only about a minute before I got the jitters and switched it off. I think I'll need a cooling fin.
If the 7805 died of heat, would there be the input voltage on the output (which would probably destroy the iphone) or would there simply be no voltage on the output anymore?Posted by: Tobsel on Sunday, September 13 @ 02:41:06 MYT |
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| Tobsel: the 7805 will almost never die of heat because it has an internal thermal protection that limits everything down to 500ma if it gets too hot. Get a cooling fin and it should work fine. If it died of heat, output should be zero, unless you get an internal short which is unlikely.Posted by: tzywen (http://tzywen.com) on Sunday, September 13 @ 22:46:31 MYT |
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| Hi; I'm the Public Relations Manager for MobileSyncBrowser: As your online publication is in touch with news about iPhone Technology and Applications, I'm writing to tell you about MobileSync Browser, in its latest 3.1 beta version, the exclusive pre-release of this application. You can try MobileSyncBrowser for free at mobilesyncbrowser.com I'm attaching the press release which outlines all the useful characteristics of MSB, now in its third generation. You are welcome to download the free trial, and if you like what it does, what it offers and how it behaves, would you kindly write a review or use the attached information to let your readers know about MobileSyncBrowser? MSB is available in English, Spanish, French and German, but will support any iPhone, regardless of language. If you have questions or comments, please write back directly to the developer, Vaughn S. Cordero at audiobinderATmacDOTcom, or reply to my email. Thank you for your help. -- Madeleine D. Quilichini, Public Relations, MSB e: mad_copyATyahooDOTcom -----
Press Release, for Immediate Release. [You are receiving this because you are on our Press Contacts list. If you want to stop receiving these updates, wish to add or change your address, email us at audiobinder@mac.com or mad_copy@yahoo.com] MobileSyncBrowser 3.1 introduces groundbreaking backup management features San Juan, Puerto Rico, USA – September 2009 – Vaughn S. Cordero of VSC/Macsupport, is pleased to announce that the popular application, MobileSyncBrowser has added backup management in its latest release and is now available for download at mobilesyncbrowser.com MobileSyncBrowser (MSB) is the simple, intuitive software utility to view, protect and recover your iPhone and iPod Touch data from your Mac or Windows PC. MobileSyncBrowser 3.1 adds two groundbreaking features to manage and enhance backups and restores. CoreRestore CoreRestore allows the user to create special backups with specific files to restore their devices at a later time. This is an invaluable aid when a device is having problems and a Reset/Restore simply causes the issue to reappear. Now users can reset their device and restore only their 'core' personal data without restoring settings files that may cause problems. Users can also save application-specific preferences and even game stats for later use. RollBack Rollback allows users to keep older, historical backups for restoration. Because iTunes normally keeps only the most recent backup, users may find the current backup lacks important data that existed in a previous backup. MSB users now have the option to prepare these 'RollBack' copies ahead of time. MobileSyncBrowser is available for US$10. A Plus license is available as well for USD$20, which enables additional data recovery features. ------------ About MobileSyncBrowser: Introduced in 2007, MobileSyncBrowser (MSB) is the iPhone backup utility that allows users access to their SMS Messages, Notes and Call History from the their iTunes backups to view, archive and export the information contained within. MSB was the first of its kind and remains the most complete, cross-platform (Mac and Windows) solution available to the public. It is user-friendly and presents a simple, iPhone-like interface. Technical Contact: Vaughn S. Cordero audiobinderATmacDOTcom Phone: 787.649.6227 Press Contact: Madeleine D. Quilichini mad_copyATyahooDOTcom # # #
Posted by: madeleine diaz quilichini (http://mobilesyncbrowser.com) on Thursday, September 24 @ 14:58:40 MYT |
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| I have been working on this very project and came across this long posting as I was trying to find out why my solar power charger was not working.
I have an iPhone 3G.
I am sending 5 volts down pin 1. What is the popular, official way I should be handing what goes down pin 2 and 3. What resistors should I be using?
I do have a regulator, the 7805 one. When cell was pushing 8 volts down the line, I connected the +ve wire in the input and the a wire coming out the output but by read still notice that it was still 8 volts? Where might I be going wrong? I have for the moment removed the series / parallel (I forget which one) of cells to only produce 4.5 volts for one which should be fine, yes?
Could someone help me out?Posted by: JN on Monday, October 12 @ 10:03:41 MYT |
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| JN: The schematic shown on the post works well for me. You need to be pushing 5v and at least 500ma to the iPhone before it will consistently charge. Can your solar panel provide the required current?
As for the regulator, make sure it's connected the right way round, or try another regulator. With 8volts, it should be working. 4.5v is not enough to charge the iPhone.Posted by: tzywen (http://tzywen.com) on Monday, October 12 @ 23:26:58 MYT |
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| I tried various two, three and four resistor combinations. Nothing worked. I found that the 3GS datalines put a significant load on the circuit. So changing to lower value resistors sorted the problem out.
My 2xAA boost circuit gives out 4.92v. With these three resistors in series between the rails: 56K, 22K, 56K the theoretical voltages should be 2.06v and 2.87v. With the 3GS connected and charging the voltages measure 1.72v and 2.48v.
Hope this is helpfull to someone.Posted by: MegaTesla on Wednesday, November 25 @ 05:28:56 MYT |
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| MegaTesla: have you measured the 5v supply when it's connected to the iPhone? If the supply is unstable or if it drops too much below 5v it will not charge. For troubleshooting, I suggest using a proper voltage regulated bench supply (you can also use a PC power supply and tap from the +5v line) to see if the circuit is working. In many cases the power supply was the culprit.Posted by: tzywen (http://tzywen.com) on Wednesday, November 25 @ 18:08:14 MYT |
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| Any reason this wouldn't work with a small solar panel for a power supply?Posted by: dean (http://rhythmconstruction.com) on Friday, November 27 @ 12:37:20 MYT |
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| dean: if your solar panel can supply steady 5v under load there's no reason why this won't work. but you may have a problem sustaining the 5v with a small solar panel since the iphone draws quite a big current (>500ma) during charging.Posted by: tzywen (http://tzywen.com) on Saturday, November 28 @ 01:03:43 MYT |
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| tzywen, thanks for your help! I still can't get this to work. Let me 1st mention that I am not an electronics guy! The solar panel I am trying to use is fairly large. 5 watts / 350 mAmps / 24 volts. I have this run thru a 5 volt voltage regulator which is putting out 4.5 volts. Is that my problem? I have the resistors configured as shown above, but I don't see the lower voltage that I am supposed to have on pins 2 - 3Posted by: dean (http://rhythmconstruction.com) on Saturday, November 28 @ 04:06:31 MYT |
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| 100 ohm instead of 100K ohm! I did say I wasn't an electronics guy right? By the time I figured it out it was dark, so I couldn't actually try it with my solar panel. I tried it with a 9 volt battery for a power supply and it worked fine. Thanks again!Posted by: dean (http://rhythmconstruction.com) on Saturday, November 28 @ 08:51:38 MYT |
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| | I am not electronically minded so i thought this was complicated. I went to jaycar and got a 10 AA battery holder and a cigerette car adapter. Went to big w and bought the car charger for ipod and iphone. as well as 10 AA 1.2 V 2500 mAh Varta batteries (3 packs of 4). Soldered the battery pack to holder, recharged batteries and thats it. Problem is, you need to put it in a holder so u can carry it around in ur bag or something. Posted by: dottyau on Wednesday, December 02 @ 17:35:37 MYT |
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| Hi, guys,
thank you for sharing your experience.
For those playing with voltage regulators I can recommend this step-down switching converter:
http://www.sureelectronics.net/goods.php?id=837Posted by: Andrey on Friday, December 18 @ 08:01:42 MYT |
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| Hi, just a little suggestion for those need to reduce voltage only a little bit (i.e. from 5.8v to 5.0v). You have to put a simple diode 1N4001 in serial connection on +5v source; at approx. 0.5A (500mA) of current as per charging our iPhone you will have a drop of voltage amount of approx. 0.7v. Of course you may insert two diods and have 2 x 0.7v of dropping voltage...
This kind of diods (1N4001) can support 1A and 50v maximum, usefull for our purpose. We do not have significant power dissipation...
+5.8v o---------DIOD------o +5.1v
GND o---------------------o GND
Please pay attention the diod has a polarity (+ and -); connect the plus source to + of diod, connect the plus destination to - of diod (- of diod is signed with a "-"). If you connect wrong version the diod, simply you will not have power to destination iPhone.
Hope this may help someone.
Posted by: zoncatan on Friday, December 25 @ 20:05:38 MYT |
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| zoncatan: thanks for sharing, using a diode is indeed one of the easiest way of dropping voltage in low current circuits!Posted by: tzywen (http://tzywen.com) on Saturday, December 26 @ 14:42:39 MYT |
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| Супер!!
Спасибо за информацию, помогла! :) Posted by: Dobriinah (http://4pda.ru) on Friday, January 15 @ 02:23:00 MYT |
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| Easiest solution that evidentially works:
Short D+ and D- and put 2V (>1,3V) on it! Thats all! Voltages on D+ and D- don't need to be different. You can do this with just two resistors:
0V---50k---2V---75k---5V
This way you can pick your 2V right from the 5V USB voltage - and this will work with ANY USB charger ;)
Any quetions or comments to reno_s@gmx.netPosted by: Reno_S on Monday, January 18 @ 22:22:18 MYT |
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| Reno_s:
I tried this method but with 2 100k resistors, I found the suggestion on a different site. When I did this, it gave me the "charging" Icon, but did not in fact charge at all. I left my phone plugged in for about an hour and the power level actually went down abou 5%Posted by: gonz on Tuesday, January 19 @ 05:23:04 MYT |
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| @gonz:
with 2 100k you get 2.5V.. Maybe that is too much. I tried this method even with 4 NiMH batteries (4.8V) and it charged.. This gives me 2700mAh extra power.. This way I have a mobile energy pack, when no wall plug is near ;)Posted by: Reno_S on Wednesday, January 20 @ 00:19:21 MYT |
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| | I don't have an IPhone, I have a Droid, but it has the same problem charging from an ordinary charger. But after building the circuit with the resister, I found out that the two data lines only need to be shorted to each other and not connected to any voltage. I tried this with my Droid and it works. This seems to be part of the USB specification (from http://pinouts.ru/Slots/USB_pinout.shtml [pinouts.ru]): "A simple USB charger should short the 2 data lines together. The device will then not attempt to transmit or receive data, but can draw up to 1.8A, if the supply can provide it." I connected my Droid to a 5V power source using a USB cord that I had opened up, cut the two data lines (white and green) and shorted them to each other on the Droid side. It charged perfectly. Posted by: David on Friday, January 29 @ 22:04:23 MYT |
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| man thanks for breaking this down!
i made a solar usb charger that easily charges my old ipod but couldnt for the life of me figure out why the iphone wouldnt charge. all i gotta do is add 1 more cell and the resistors.
thanks again man!Posted by: StJohnny on Sunday, January 31 @ 04:24:27 MYT |
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| tzywen: I added 3 resistors that I could find and got the following voltage readings on my cheapo wall charger (bought from KK, Sabah):
5.6V -- 110K -- 2.86V -- 20K -- 2.42V -- 110K -- 0V
Thought I'll run by you before connecting my iPhone 3GS to it. Do you think that's safe or will it burn my iPhone (especially the 5.6V)?Posted by: Boon on Wednesday, February 03 @ 03:09:57 MYT |
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| | The charger with the 3 resistors does not charge the iPhone. :( Posted by: Boon on Thursday, February 04 @ 08:54:55 MYT |
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| Boon: I assume you're using the 3GS? MegaTesla had mentioned something in the comments above:
"I tried various two, three and four resistor combinations. Nothing worked. I found that the 3GS datalines put a significant load on the circuit. So changing to lower value resistors sorted the problem out."
Hope that can help you outPosted by: Tzy Wen (http://tzywen.com) on Thursday, February 04 @ 22:42:15 MYT |
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| | Will try dropping both 110K resistors to 56K and see. Posted by: Boon on Friday, February 05 @ 11:22:20 MYT |
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| | Nah, dropping to 56K resistors did not work. Posted by: Boon on Monday, February 08 @ 05:22:35 MYT |
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