CURRENT necessary to feed nano Arduino

Hello everyone, I'm doing a project and need to scale the amount of required current. I wonder what the required current only to connect the Arduino. The inputs and outputs I know use 40mA, as the arduino alone consumes I do not know.
If someone also know, I am using a relay Shield 4 outputs, like this .

Anyone know how much current is needed for it?

Thank you.

I wonder what the required current only to connect the Arduino.

For a Uno it is about 35mA.

The inputs and outputs I know use 40mA,

No they don't.

I am using a relay Shield 4 outputs, like this

Like what?

Grumpy_Mike:
For a Uno it is about 35mA.
No they don't.
Like what?

As stated in the https://www.arduino.cc/en/Main/ArduinoBoardNano I \ O using 40 mA each.

Grumpy_Mike:
Like what?

Like a this http://s3.amazonaws.com/img.iluria.com/product/202805/4BF6C9/450xN.jpg

you know how much current it consumes?

As stated in the https://www.arduino.cc/en/Main/ArduinoBoardNano I \ O using 40 mA each.

No it doesn't please read it again.

It says that the maximum current you SHOULD draw from an output pin is 40mA. When a pin is connected to nothing it consumes nothing, when a pin is made an input it draws nothing. If a pin is an output and is connected to a 10K resistor it draws 0.5mA.

Like a this http://s3.amazonaws.com/img.iluria.com/product/202805/4BF6C9/450xN.jpg

So you post a picture. Do you expect me to know what that is and then google a link to it and look up the data sheet? Put a bit of effort into your posts.
Start off by reading How to use this forum it will tell you how to ask a question and how to respond when you don't understand what you have been told.

If your relay board is this one: arduino-4-relays-shield then the power consumption is 35 mA per relay when they are switched on. Thus about 140 mA worst case. Note that the physical form factor of this relay board is compatible with the Uno, not the Nano.

I think you are getting the 40 mA per pin from the per pin absolute maximum rating. This probably isn't the parameter you want. The quiescent current for an Atmega328 board without peripherals should be less than 50 mA. The 35 mA value Grumpy Mike suggests sounds like a reasonable typical value. Actual current draw depends upon what you're doing in your sketch.

Thus your total current is typically 35 mA + N * 35 mA where N is the number of relays activated at any moment. Worse case with all relays activated is about 175 mA.

*** Update: While I was writing, I see the OP posted a picture of a different relay board than I've assumed above. If there are no specs for that board, looking up the relay part number in the picture suggests 70 mA coil current for the relay as typical rather than the 35 mA in my example calculation. ***

Actual current draw depends upon what you're doing in your sketch.

Well no actually.

MrMark:
If your relay board is this one: arduino-4-relays-shield then the power consumption is 35 mA per relay when they are switched on. Thus about 140 mA worst case. Note that the physical form factor of this relay board is compatible with the Uno, not the Nano.

I think you are getting the 40 mA per pin from the per pin absolute maximum rating. This probably isn't the parameter you want. The quiescent current for an Atmega328 board without peripherals should be less than 50 mA. The 35 mA value Grumpy Mike suggests sounds like a reasonable typical value. Actual current draw depends upon what you're doing in your sketch.

Thus your total current is typically 35 mA + N * 35 mA where N is the number of relays activated at any moment. Worse case with all relays activated is about 175 mA.

*** Update: While I was writing, I see the OP posted a picture of a different relay board than I've assumed above. If there are no specs for that board, looking up the relay part number in the picture suggests 70 mA coil current for the relay as typical rather than the 35 mA in my example calculation. ***

I believe that there should be a current amplifier in the shield relay because if the maximum current that an output pin can offer is 40 mA it would not be enough to trigger the relay. So I believe it is less current draw. I found nothing related.

Grumpy_Mike:
No it doesn't please read it again.

It says that the maximum current you SHOULD draw from an output pin is 40mA. When a pin is connected to nothing it consumes nothing, when a pin is made an input it draws nothing. If a pin is an output and is connected to a 10K resistor it draws 0.5mA.
So you post a picture. Do you expect me to know what that is and then google a link to it and look up the data sheet? Put a bit of effort into your posts.
Start off by reading How to use this forum it will tell you how to ask a question and how to respond when you don't understand what you have been told.

I'm sorry, already packed the picture, thank you.

I believe that there should be a current amplifier in the shield relay because if the maximum current that an output pin can offer is 40 mA it would not be enough to trigger the relay.

Typically there are opto isolators on the board so all the current draw from the Arduino's output pin is the current it takes to drive an LED, typically 10mA.

Did you read the forum rules? It says not to alter the first post because it makes the following posts look silly.

akirado:
I believe that there should be a current amplifier in the shield relay because if the maximum current that an output pin can offer is 40 mA it would not be enough to trigger the relay. So I believe it is less current draw. I found nothing related.

If you follow the link to the relay board in my previous post there is a schematic. It has FET switches on each of the control inputs. What this means is that there is virtually zero current through the Arduino GPIO pins. The relay current (35 mA for the one I linked) flows through the relay coil and the FET switch, but not back to the Arduino pin.

On the picture you posted, there appear to be four opto isolators (the 4-pin black rectangles on the bottom of the picture) plus transistors labeled Q1 through Q4 which most likely drive the relay coil. Without schematics (and the ability to interpret them) or board level specifications we can only guess, but my guess is that the Arduino will need to drive an LED load (10-20 mA per pin) and the relays are actually switched by the transistors.

So for your board I'd estimate 35 mA quiescent for the Arduino + for each relay activated (10 mA for opto isolator + 70 mA for the relay coil). Typical current with all relays activated would be on the order of 275 mA.

Anyone know how much current is needed for it?

See the schematic and data on that relay board HERE:

DISCLAIMER: Mentioned stuff from my own shop...

Here's how to make connections to take advantage of opto isolation. It's very simple ...

MrMark:
If your relay board is this one: arduino-4-relays-shield then the power consumption is 35 mA per relay when they are switched on.

But it's not.
The common blue 5volt sugar-cube relays use 75-80mA each.

Grumpy_Mike:
Typically there are opto isolators on the board so all the current draw from the Arduino's output pin is the current it takes to drive an LED, typically 10mA.

Those 4-relay boards have an opto LED (~1.2volt), an indicator LED (~1.8volt) and a 1k resistor in series.
The Arduino pin has to sink ~2mA, not 10mA.

A Nano might just be ok powering four relays from USB, but could get in trouble if powered through V-in.
Powering the relay board seperately (with opto isolation), like in post#10 is much better.
Especially when the relays are used to switch mains powered devices.
Leo..

Wawa:
But it's not.

We know that now, but the first post post is no longer the original first post.

MrMark:
We know that now, but the first post post is no longer the original first post.

I just packed the image was not showing up, I have not changed anything post.

Wawa:
But it's not.
The common blue 5volt sugar-cube relays use 75-80mA each.
Those 4-relay boards have an opto LED (~1.2volt), an indicator LED (~1.8volt) and a 1k resistor in series.
The Arduino pin has to sink ~2mA, not 10mA.

A Nano might just be ok powering four relays from USB, but could get in trouble if powered through V-in.
Powering the relay board seperately (with opto isolation), like in post#10 is much better.
Especially when the relays are used to switch mains powered devices.
Leo..

I will perform the connection of the shield relay using an external source to avoid problems with the Arduino.

In short then, the Shield relay consumes about 80mA each relay, and the plate Arduino about 35mA, alright ?

I will use a source 1A which will be more than enough.