Well, after a lot of searching, I found out what the resistances in the iPad charger are. However, it seems that the resistances used don't exist in PHP form. And since I plan on using through hole resistors, that seems to be a problem.
I'm sure this is easy to figure out, but I can't seem to... Can anyone help me out, and tell me what common through hole resistance values to swap these out with? Also, I'm sure you noticed, but they're voltage dividers, so it's not so much the value that matters, as the output voltage.
Jeremy1998:
That may be true, but $0.25 for 1 resistor is a bit much.
So use a couple of junk box small 100k ohm 10 turn trimmer pots and set to the correct voltage values.
Lefty
Well, I am making 12 of those things, so pots have already been eliminated as an option. I guess I will just pay 25 cents each... Not THAT much I guess
I may well be wrong, but I can't believe that they have to be that precise. For the 49.9K I would just get a 50K, the 75K should be readily available and the 43.2K looks a lot like 43K or 47K to me. I mean, what's the tolerance of the power supply? It has to change as the battery goes up and down in charge....right?
draythomp:
I may well be wrong, but I can't believe that they have to be that precise. For the 49.9K I would just get a 50K, the 75K should be readily available and the 43.2K looks a lot like 43K or 47K to me. I mean, what's the tolerance of the power supply? It has to change as the battery goes up and down in charge....right?
I thought about that, then went against it because I wanted it to be perfect, but at this point, $ 4.50 total on ebay for all the resistors is way better than $8 + S&H at DigiKey... EDIT: It ended up being $3.47 actually this is nice
eBay, and close values it is... Already ordered, and shipped. Thanks for the suggestions dude.
I am so tickled that apple made the ipad. The Chinese came out with a ton of really good 5V 2A supplies in response and we can pick them up for as little as 3 bucks (US). I have about five of them around the house and a couple in a box waiting to be used. Heck, I even took the guts out of one and used it in a project box.
I don't have an ipad, but just love those supplies.
draythomp:
I am so tickled that apple made the ipad. The Chinese came out with a ton of really good 5V 2A supplies in response and we can pick them up for as little as 3 bucks (US). I have about five of them around the house and a couple in a box waiting to be used. Heck, I even took the guts out of one and used it in a project box.
I don't have an ipad, but just love those supplies.
I don't have an iPad, or an iPad charger... But I plan to, hence the reason for having a 2 amp supply on the charger I'm making...
And if you we're curious, I'm making a custom headboard... And it's gonna have usb to charge iPhones, iPods, and in the future, an iPad... This is being thuroughly documented, and will be posted on various sites, including here.
As more devices demand more current for charging from USB, other manufacturers are using the same voltage-id method as Apple to identify supplies that can provide >500mA of current. It is becoming a quasi-standard.
NiHaoMike:
The official standard just jumpers the lines together.
The official standard also only allows for 500mA of current. The pull-up method is a way for devices to (passively) know if the source is capable of more current.
The dumb thing is just how long it's taking for an actual standard to become reality. Last I read, "most" new mobile phones will comply with the new standard by Jan 2012.
this is nice