How much current does an Arduino Uno draw?

Take a look at this project: AC voltmeter project with Arduino

How much current does the Arduino draw when I am reading something with analogRead()? Will it be less than 20mA or more? Will this current depend on the voltage at the pin?

Also (not related to the above link): How much current can an Arduino draw at maximum from the power supplied to it? (Say all the I/O pins are working)

Whitch one of the Arduiunos? Search for specifications for the board You use.

Beware of that project, it is a good and easy way to blow up an Arduino. Also, stay away from mains voltages, it's just too dangerous for the inexperienced. Just another really crappy and dangerous project on the web built by someone who is clueless about safety, component ratings and lethal voltages.

The current into an analog input pin is next to nothing, meaning less than microamps. The voltage must be less than 5 volts and voltage will not change the current in any meaningful way.

The maximum current allowed into the atMega328 is 200 ma total for all pins combined with no more than 20 ma on any one I/O pin.

FWIW, a bare Uno will draw about 50 ma from its supply.

WattsThat: Beware of that project, it is a good and easy way to blow up an Arduino. Also, stay away from mains voltages, it's just too dangerous for the inexperienced. Just another really crappy and dangerous project on the web built by someone who is clueless about safety, component ratings and lethal voltages.

The current into an analog input pin is next to nothing, meaning less than microamps. The voltage must be less than 5 volts and voltage will not change the current in any meaningful way.

The maximum current allowed into the atMega328 is 200 ma total for all pins combined with no more than 20 ma on any one I/O pin.

FWIW, a bare Uno will draw about 50 ma from its supply.

Thank you for the guidance. Those figures will help. Yes, I will also look after safety issues.

Wrichik.

Railroader: Whitch one of the Arduiunos? Search for specifications for the board You use.

The title of the thread states: "Arduino Uno". In addition, it's Rev3.

Will this current depend on the voltage at the pin?

No.

Actually, it's not dangerous (as long as you don't touch the power-line side of the transformer). The transformer lowers the voltage to a safe level and electrically-isolates the Arduino (and you) from the power line.

But there is one thing I'd change - The voltage divider should go on the "DC-side" of the rectifier (D1). The way it's currently built there is nothing preventing the analog input from floating-up and you might not read zero with zero-voltage. (The electrolytic capacitor might have enough leakage to get you down to zero, but it's not a reliable way to do it.

WrichikBasu: Take a look at this project: AC voltmeter project with Arduino

The capacitor is shown connected the wrong way round. The white stripe on a capacitor shows the negitave side.

DVDdoug: Actually, it's not dangerous (as long as you don't touch the power-line side of the transformer). The transformer lowers the voltage to a safe level and electrically-isolates the Arduino (and you) from the power line. ...

Yeah, but... I know you looked at the project to comment about the crap design that it is - but did you really look at the photographs? Where the author has meter probes shoved into a 230V mains power strip with 24 gauge wires under the probes? One of the red wires leading out of the connections has a bare solder connection floating above the metal core of the transformer, an accident just waiting to happen.

One of the screenshots show a measured voltage of 234.14 volts. Okay, so they don't show the circuit to measure 230 volts but I'll bet you someone will try it. Guaranteed.

The author of the Circuit Digest post is a complete idiot and he's quite lucky he did not become a winner of a Darwin award. Looking at such crap posted on the web and not pointing out the inherent dangers to those that have zero idea what they're playing with is not being a good steward of the hobby (or whatever it is that you want to call what the people on this board do with these little modules).

/rant