How to Make Blackberry Charger at Home - Mini USB

Blackberry cellphones can’t be charged with ordinary usb chargers. They have a significant logic for charging from USB. Here I will explain the charging circuit logic of mini usb for blackberry cellphones. This is how you can make a blackberry charger at home. A small and working circuit describes blackberry charging logic.

Usually most of the old blackberry phones has mini usb ports. The mini usb connectors has 5 pins instead of 4 like ordinary USB cable(shown in image).

This circuit has pin1 +5v supply  pin2 and pin3 are shorted then connected with pin x (that is additional in mini usb) through a variable resistor of 10kΩ, pin4 has -5v(gnd).

NOTE: the variable resistance of 10kΩ is set to near 7kΩ. The Circuit is tested successfully with Blackberry Bold 9000