Does the Uno R3 reduce power voltage at a pin to power a shield ?

Projects General Guidance
1

Does the Uno R3 reduce voltage on one of its pins to supply 5v to power an Itead 3G shield?

2

Hansen70:
Does the Uno R3 reduce voltage on one of its pins to supply 5v to power an Itead 3G shield?

I'm confused with this statement. What exactly are you asking? Can you give more specific details as to what is going wrong with your project?

If it's a power problem, a good fix is to power the shield off a separate power supply.

3

Your question doesn't make sense.

Is this related to this question (that also didn't make sense).
https://forum.arduino.cc/index.php?topic=479459.0

Please state your PROBLEM, not the SOLUTION you think is right.
Leo..

4

Hansen70:
Does the Uno R3 reduce voltage on one of its pins to supply 5v to power an Itead 3G shield?

No.

5

Power_Broker:
I'm confused with this statement. What exactly are you asking? Can you give more specific details as to what is going wrong with your project?

If it's a power problem, a good fix is to power the shield off a separate power supply.

I am new to using Arduino: I have a Uno R3 that the input voltage is 12v, and if I attach a G3 Shield to it (which calls for 5v to operate it), am I right in assuming that the R3 has a voltage regulator built in, supplying the shield with 5v power though one on the pins?

6

Hi,
Look at your R3,each pin down the sides of the PCB are labelled, you will find a gnd and a 5V pin.

Yes the R3 does provide 5V through that pin if your shield is plugged into the R3.

Tom... :slight_smile:

7

Yes, but if you connect 12V to the UNO and then try to draw a lot of power from the 5V pin (such as an LCD backlight) then you can overheat the voltage regulator.

For a GSM/3G shield, I'm not sure. The top few hits on Google don't seem to show what their peak power consumption is. I imagine it could over-stress the UNO regulator with a high voltage (>=12V) input.

8

I found a 300mA draw from the 5volt pin in the shield's documentation.

If correct, then a 12volt supply on the DC socket dissipates ~2.2watt in the 5volt regulator of the Arduino.
Way too much. The regulator will overheat.
A 9volt supply on the DC socket would halve the heat in the regulator, and could just be just ok.
Leo..

9

Wawa:
I found a 300mA draw from the 5volt pin in the shield's documentation.

If correct, then a 12volt supply on the DC socket dissipates ~2.2watt in the 5volt regulator of the Arduino.
Way too much. The regulator will overheat.
A 9volt supply on the DC socket would halve the heat in the regulator, and could just be just ok.
Leo..

When I receive the itead shield, I hope it has instructions on what maximum voltage I can use on the Uno (that it draws power from). Do you think it will?

10

Do you think it will?

No.
But the answer is 5V.