# Have Arduino uno got enough current for vibration motor ?

I have a vibration motor which is run with 2.5-3.5V, max current is 120 mA and motor resistor is 29 ± 6 ?.

So I have a project which contains LCD, phototransistor, IR LED, some buttons, potantiometer and vibration motor. I dont have a idea about that arduino uno's electric current is enough for this project. I know that digital pin max. current is 40 mA, is it also valid for 3.3V pin and 5V pin ?

Thanks.

Is 120mA more then 40mA?

steinie44: Is 120mA more then 40mA?

is it [40mA] also valid for 3.3V pin and 5V pin ?

is it [40mA] also valid for 3.3V pin and 5V pin ?

So.........

So? He knows 120 is too much for an i/o pin, but is asking if it's too much for the power supply pins.

jeolex: I have a vibration motor which is run with 2.5-3.5V, max current is 120 mA and motor resistor is 29 ± 6 ?.

So I have a project which contains LCD, phototransistor, IR LED, some buttons, potantiometer and vibration motor. I dont have a idea about that arduino uno's electric current is enough for this project. I know that digital pin max. current is 40 mA, is it also valid for 3.3V pin and 5V pin ?

Thanks.

The 3.3V regulator on an Arduino Unu is one of these:

http://www.ti.com/lit/ds/slvs522n/slvs522n.pdf

Max current is 150mA

JimboZA: So? He knows 120 is too much for an i/o pin, but is asking if it's too much for the power supply pins.

Hopefully he's not going to power his 3.5V motor from a 5V pin...

NO. Not with all the rest of that stuff connected.

fungus: Max current is 150mA

This answer what I have asked. Thank you. I guess 150 mA will not enough for my project. And I am new with arduino and electronic things. I research from websites and if I am wrong please correct me,

Can capacitor use for strengthen the current ? For example if my arduino's current is not enough for motor, so I use capacitor which is suitable for circle (I am not know yet). Am I right ?

What you need to do is power the vibrator externally to the Arduino, but probably control it from the Arduino via a transistor.

Have a look here for example.

I have looked example. But I don't want to use external power. I just want to connect arduino to adapter and use my device. Is it possible ?

jeolex: I just want to connect arduino to adapter and use my device. Is it possible ?

Ok I get it. Thank you so much :)

The Arduino's a controller remember, not a power supply 8)

The Arduino's a controller remember, not a power supply

This is true, but he specified his motor only used 120mA and the 3.3V regulator can source 150mA max. So why is that a no exactly?

I know it is not good to get close to your current capacity like that, but I would expect it to still work. And considering likely the rest of his circuity is using 5V regulator. And USB can source 500mA so he has no problem there (more current capacity yet if using an external supply).

And there is minimal harm in trying it. The worst thing that happens is the current draw is high enough to reset the Arduino. in which case it will become immediately obvious that motor will not work from Arduino 3.3V pin.

Can capacitor use for strengthen the current ?

Not to strengthen it, but it could be used as like a helping hand, so when the motor first starts to spin its initial current surge will come from capacitor not all from the 3V3 regulator. You would want a pretty large capacity capacitor though and it would need to be rated for the appropriate voltage.

brushed motors usually have a high start-up (stall) current, like 6~20 times the normal current.

you should get ready for that before you digitalWrite(MOTOR_PIN, HIGH).

These informations are so clear. Thanks for clarify me. So I have a idea but I don't know again it is possible or not :)

For example I have a adapter which is pretty enough for all of my project parts. And from adapter one of my output connect to arduino with some parts which are make it suitable for arduino card. The other output connect to dc motor, LCD, etc. and act as an external power. Is it possible ?

Palatis: brushed motors usually have a high start-up (stall) current, like 6~20 times the normal current.

you should get ready for that before you digitalWrite(MOTOR_PIN, HIGH).

My vibrator motor's start-up current max 120 mA. It's mean that not possible to use pins for run dc motor. So I need to entegrate external power (for dc motor, LCD etc) and arduino card power in one power supply :)

Which Arduino are you using. The Uno has a max current draw on 3V3 pin of 50mA per the Arduino info page. 5V pin is 200mA. Not sure if different models have different regulators or not.

And is the 120mA a true max or is that the continuous operating current. It may be the motor only takes 20mA or something continuous and so that 120mA figure may account for the initial current surge. Do you have a datasheet?

You are corrent the pins are not at all suitable to drive motor. You could get away with 5V pin if you used a low drop out 3V3 regulator, but that might be not options, just depends.

And from adapter one of my output connect to arduino with some parts which are make it suitable for arduino card. The other output connect to dc motor, LCD, etc. and act as an external power. Is it possible ?

That's actually what I was picturing: the Arduino in parallel with various components, provided the voltages are either the same or adjusted somehow.

Here's a question though: presumably you want to switch the vibrator off and on? So even if it's supplied from the on-board 3V3, you'll still need to switch that with a transistor. Because if you don't, and simply switch the other side of the motor with an i/o pin, then that pin may be over-drawn.

And don't forget the flyback diode....