Hello Yoshidk,
Look for the datasheet of ULN2001. There you found also ULN2003 for TTL and CMOS -using. There the base - resistor is 2,7kΩ.
Take this value and good is. :-D
If you only have 425µA for base current you need R = (Vb-2xVBE) / IB = (5V - 1,4V) / 425µA ≈ 8,5kΩ.
So use 10kΩ.
All drivers of ULN200x are equal, only the base resistors are different.
– ULN2001 (general purpose, DTL, TTL, PMOS, CMOS)
– ULN2002 (14 - 25 V PMOS)
– ULN2003 (5 V TTL, CMOS)
– ULN2004 (6 - 15 V CMOS, PMOS)
Regards
Rainer