Resistor question regarding a solenoid project

Other Hardware General Electronics
1

Hello all,
I am trying to control a 12V solenoid with Arduino. I am a beginner and I am following the instructions from this video (Arduino Lesson 4 - Solenoid control using a Transistor - YouTube).

I have a 12V large solenoid (I think it takes around 1mah to work), an Arduino Uno, one Tip102 Transistor, one IN4001 Diode in my circuit, which I am powering with a 12V 1500mah power adaptor. I am getting confused with calculating the resistor I should use. The guy is using a 1K Resistor but his power adaptor is 1am (mine is 1.5am).

I was wondering if anyone can tell me what amount of resistance I should use. Thank you.

2

If you mean the base resistor then the value is independent on the power source. 1k should be okay with a 5V controller and Tip102 Darlington transistor.

Power adapters are rated in voltage (V) and current (A, 1A = 1000mA). Batteries are rated in voltage and capacity (mAh).