Hi, I've made a battery operated mobile charger using this circuit. I am able to charge the basic phones (with 2100mAh battery) with it. But the problem is, I couldn't charge any smart phones (with 1500mAh battery) with it. Even the charging indicator is not showing when I connect it to a smart phone. What could be the reason? and how can I solve it? Please help me.
Take a look at the Adafruit's Mintyboost. In it's early versions it has the same problem but after it turns out that many smartphones need a precise value of resistors connected to their D- and D+.
For a basic phone,there is no need for D+ and D- differential pair to be configured.When it comes to smart phone,the D+ and D- in the phone should be configured.Some smart phone's D+ and D- is connected with a resistor and Vcc and ground is given to configure that,charging is done.
- one suggestion I can give you is that,connect a 1.5K ohm resistor across the D+ line and the Vcc.
- The circuit diagram which I found in the internet,take a look on it.
- Dont worry about the rectification part.The iput you gave is already a DC and voltage regulation is done by your lm7805 IC.Just refer the D+ and D- wiring.Put a fairly good value of resistance,in the range of 2K ohm like that.
- Try this configuration