Homemade USB-charger

Thread Starter

Alfanano

Joined Feb 16, 2009
2
Hi. I'm working on a little project that I decided to do after I bought 2 USB-chargers who got there power from AA/AAA batteries but I have ran into some problems and hoped that you could help me a bit.

The components are:
Battery pack for 4*R06 (generates 6 Volts)
1 +5VDC regulator (LM2940T)
1 100uF capacitor
1 USB type A contact

They are all connected like this:


Checking with a voltmeter I get 4.95 V out but when I connect a USB product like cellphone or Ipod, it only reacts to that something is being connected but no charger icon comes up. So I guess that I have to do something with the to remain pins on the USB-port (D+ and D-). I read that using a 100k resistor and connecting it in a special way could trigger the units to charge but I have no idea of how
So hopefully someone of you can help me what I should add to my circuit and how to make this work sucessfully.
 

Thread Starter

Alfanano

Joined Feb 16, 2009
2
Don't quote me, but I think this might be the way to accomplish the task.
Thank you for your answer iONic. Took some time today and made a more professional wiring diagram then the last one. Put in the suggestion from iONic and the result became this:



Do any of you think it will work or fry everything I connect?
 

wayneh

Joined Sep 9, 2010
17,496
Do any of you think it will work or fry everything I connect?
First a quibble - it's convention to put the higher voltage towards the top of the schematic.

It won't fry if the polarity is right (I didn't check) but I don't think that will work. It puts full voltage on the data pins, albeit through the 10k. Most solutions I've seen require a voltage divider so that a specific voltage is applied to each pin. This fools the device into thinking it has been connected to a proper charger. The voltages required may (I'm not sure) vary amongst devices. So it may take some tinkering.

Look up the Minty Boost project and I think you'll find all the info you need.
 
Top