problem controlling 2A motor

hi guys,
i have strange problem using 2a motor , tip122 transistor.
i want control motor using pin 9.
the motor starts not have enought power-as if connect directly battery.
i using same schematic one:
http://www.instructables.com/files/deriv/f9l/kdfg/gu7fxumh/f9lkdfggu7fxumh.large.jpgi dont have cap , using 1n4007 instead of 1n4001.
i using 1.2kohm resistor , giving ~2ma current transistors base.
hfe of tip122 1000 ~2ma should able drive motor(2a - when connect free run directly on battery drawing 1.3a).i tried less resistor values problem same.
the motor starts not powerful when direclt connect battery.its runs half power when runs throught transistor
the motor rs380s 4.8v.
i tried 2 different tip122 , didn't solve problem.

the code simple:

code: [select]


int motor = 9;

void setup() {               
  pinmode(motor, output);     
}


void loop() {
  analogwrite(motor, 255);   
  delay(1000);               // wait second
}
any suggestions?
thanks in advance

could diode in backward?  short out motor , limit voltage diode forward voltage drop.

Arduino Forum > Using Arduino > Motors, Mechanics, and Power (Moderator: fabioc84) > problem controlling 2A motor

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