user66062: I've got 12V / 400mA power supply for my Wemos D1 R1, and I'm using VIN output(I need 12V for led strip). I need to change this power supply because of color, and I can't find similiar with the same parameters. The question is - Is power supply with 12V / 1A - 2A safe to use?

user2967: With very few exceptions, electronic devices only draw as much current as they need, limited by their resistance. 
The current rating on a power supply is the MAX current it can provide before the voltage drops. Having a higher current power supply may waste energy, but won't hurt anything.
According to Ohms law, V = IR 
Where V = Voltage
I = current, in amps
R = resistance, in ohms
(voltage = current times resistance.)
Or, solving for current:
I = V/R

current = voltage divided by resistance.
So if you have a 12 volt power supply, and a 100 ohm resistor, you'll get 12/100, or 0.12 amps, flowing through the resistor.

66062: <p>I've got 12V / 400mA power supply for my Wemos D1 R1, and I'm using VIN output(I need 12V for led strip). I need to change this power supply because of color, and I can't find similiar with the same parameters. The question is - Is power supply with 12V / 1A - 2A safe to use?</p>
 2967: <p>With very few exceptions, electronic devices only draw as much current as they need, limited by their resistance. </p>

<p>The current rating on a power supply is the MAX current it can provide before the voltage drops. Having a higher current power supply may waste energy, but won't hurt anything.</p>

<p>According to Ohms law, V = IR </p>

<p>Where V = Voltage
I = current, in amps
R = resistance, in ohms</p>

<p>(voltage = current times resistance.)</p>

<p>Or, solving for current:</p>

<pre><code>I = V/R
</code></pre>

<p>current = voltage divided by resistance.</p>

<p>So if you have a 12 volt power supply, and a 100 ohm resistor, you'll get 12/100, or 0.12 amps, flowing through the resistor.</p>
