I want to power up my Arduino and my Nodemcu via 12 V , 1 A power adapter (it's an AC to DC power Adapter).

Recently I have two voltages regulators: a 5 V for nodemcu and 9 V for Arduino Uno.

The question is does the 1A affect both boards or not?


In principle not. However, the voltage regulators may become quite hot, since you are going down from 12 V to 9 V and 5 V (especially the step from 9 V to 5 V is quite a lot). It depends on the current (in (milli)Amps) how hot they get.

For the adapter it does not matter, if it is 1 A or 10 A, the microcontrollers will only take whatever they need. Only if the adapter can deliver less than needed by both microcontrollers there is a problem.

The voltage regulators are not of switching type I guess, so they will use the same amount of amperes. Assuming the Arduino Uno takes 300 mA (at 5 V) and the NodeMCU 200 mA (at 12 V), you can add them together: 200 mA + 300 mA = 500 mA. Since this is less than 1 A the adapter can deliver, you are ok.

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