Hi guys, i am not sure if my plan will work so i need people to correct me if i am wrong. My plan is to get a 12V 3 pin adapter plug for the whole circuit, everything here is powered by Arduino. 16x2 LCD with backlight on (120-160mA), 3-24V piezo buzzer (20mA), 5V relay module (7-10mA), 4x4 Matrix Membrane Keypad (30mA), total 220mA.
From what I researched, Arduino can hold up to 7-12V (Total maximum current draw when powered via external power supply: 1A) and I have a 12V solenoid lock around (1.2A). I am planning to connect it in parallel circuit so the voltage will be the same and sum of the currents through each path is equal to the total current that flows from the source.
So here comes the question, if I were to get a adapter of 12V what should my current supply be? If I calculate Arduino max current 1A + Solenoid lock 1.2A, i will have to get around 2A or 2.5A supply. But if I only calculate the Ampere I need, I only need to get 1.5A supply.