Arduino connected to power supply

Hi, i want to operate my 12V DC Motor via arduino, My motor draw 0.95A starting current.
if i have an external power supply of 12V 1A should i use some buffer or should i connect it like the example below?(ignor the transistor and the resistor it just for the example)

Are you asking if you need something between the power supply and the motor? If it's a 12VDC motor you can safely apply the 12V power supply across it. If by ignore the transistor and resistor you mean you don't plan to use them then that would be an issue. The Arduino pins cannot source or sink anywhere near 950mA. If you are using the transistor make sure it can survive that current and it has a collector to emitter voltage rating above 12V.

KD494 said:

Are you asking if you need something between the power supply and the motor? If it's a 12VDC motor you can safely apply the 12V power supply across it. If by ignore the transistor and resistor you mean you don't plan to use them then that would be an issue. The Arduino pins cannot source or sink anywhere near 950mA. If you are using the transistor make sure it can survive that current and it has a collector to emitter voltage rating above 12V.

Click to expand...

about the transistor and the resistor i mean that the values in the circuit maybe not correct so ignore them. of course i must use some transistor. so actually a power supply of 12V 1A should be good enough for my motor?

Hi Omerysmi,
...should be okay, just about, as the 0.95A is only for a second and not continuously...

Good idea is: a) add the maximum current each thing (Arduino + Motor) will draw at any one moment, then do this: maximum current used in circuit * voltage of power supply = Watts needed in power supply.
(watts = power necessary to function correctly without voltage drooping if you draw the full current, and so on);

Next, b) see what your 12V/1A power supply says in Watts capability, if it doesn't provide that info., then again: multiply max. current provided * power supply voltage, if a) and b) are the same answer it will be okay.

Next, if it is one of those 5V to 12V adapters, check in the manual/instructions that the power supply really provides 1 amp at 12 volts, as sometimes they only provide 1 amp at 5 or 7 volts, and less current at 9 and even less at 12 volts (those are the sneaky adapters/power supplies that lull you into a false sense of security!)

Really, the ideal situation is to have a power supply with more current available at the right voltage than you will actually need, but you should be just okay with the 1A at 12V.