I have made a portable device charger with a 5 volt voltage regulator(7805-TO220 package),a 9 volt battery and a few capacitors.The problem is,when I connect the charger to a certain device(whose original charger outputs 5 volts and 2A) and the device starts charging, after a few minutes,the image starts flashing and then it shuts down,then the start-up screen appears,then the screen turns black and so on a few times,then it shuts down completely and remains in this state.I connected the circuit to another device whose original charger outputs 5,1 volts and 700 mA and all works just fine.
Why does the first device behave this way?
I don'think it's about the voltage or current.
The 9 volt battery is a Varta High Energy model-6LP3146. EDIT:I noticed that when charging the second device,its battery drops after a while,whether discharging on its own or being discharged by my charger(I added a diode between the output pin of the regulator and the positive terminal of the device,so it's unlikely).