Certainly you will need a current limiting resistor if you are driving them with a unipolar driver and a single transistor as you showed.
Calculate the resistance of the coils, the voltage you are driving them and simple mathematics will tell you the value of the current limiting resistor. So 1.3 volts at 3.9 amps gives you a resistance of 0.33 ohms. At 12 volts you need a 3 ohms limiting resistor that can dissipate 12.5 watts minimum. I would make it a 15 watt resistor for safety. Joe.
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