Hi all,
Sorry for this, probably stupid basic question but I'm not expert.. I would like to measure the consumers of my Arduino Mega 2560 in order to try to reduce them.
I know that I have to attach the multimeter and, if I'm not wrong, it's not a good idea to power the Arduino using USB or the power switch because, in this way, there is a power voltage regulator and my measurement could be not realistic.
Probably I have to power my Arduino using the 5v input pin. But, at the same time, this is risky because, as there is no voltage regulator, I would ask to burn the card.
I don't have battery but I have a power supply board like this: https://www.amazon.it/AZDelivery-MB102-Netzteil-Adapter-Parent/dp/B07ZFWSRM9
Can I connect the 5v output of it directly to my Arduino 5v input + GND? Is it correct or are there some risks?
In this scenario I'll punt my multimeter between the power supply and the 5v input pin.
The USB connection using your ET9000 should be just fine. Cycling the power has a minimal effect on your Arduino. The power supply board you show is for a MB102 or similar breadboard. It could power your arduino but again it does not support a lot of current. I power through the barrel connector with about 7.5V(12V will work), this keeps things cool and the additional filtering does not hurt anything. Rule #1"A power supply the Arduino IS NOT!"
In my opinion the only stupid questions are those that do not get asked. You asked a good question the best you could with the knowledge you have, that is what we are for and how you will learn. After today your knowledge will grow and keep on growing, that is what this ia all about. Please understand we ALL were in the same boat you are and with peserverience etc out knowledge grew as will yours.
Sorry your language is not shown so I responded in english.
USB power is normally regulated. It's supposed to be regulated and the power out of a computer's USB port will be regulated. You can connect to the USB port or to the 5V pin.
If you are powering through the barrel jack you are going through the Arduino's on-board regulator. And since there is some voltage-drop across the regulator you should apply more than 5V to the barrel jack.
The little on board regulator can't handle much current (and it depends on the voltage) so you can't power much "extra" through that regulator.
With a linear regulator the current-into the regulator is very-slightly higher than the current-out. The difference might be too small to measure. There will be more voltage-in than out depending on the voltage you feed-in.
With a switching (AKA "switch mode") regulator there is usually less current-in than out. (That's assuming it's a step-down regulator. There are also step-up switching regulators.) Power is calculated as Voltage X Current and since switching regulators are very efficient the Voltage X Current in is just slightly more than Voltage X Current out.
Right, the meter goes in series when measuring current. It's "slightly dangerous" because in current-mode the meter is a short circuit. That's OK if the Arduino (or your normal load) is also in series to limit the current.
But if you connect it directly across (in parallel with) the power supply you are shorting-out the power supply and you might blow a fuse in your meter, or worse. Most multimeters have a separate connection for current so you are less-likely to accidentally leave it in current mode and short something out. I've seen a few meters that can measure voltage & resistance but can't measure current because the fuse is blown.
Current measurement are not as common as voltage & resistance measurements. Sometimes you have to measure current, but more often we calculate it or just estimate. I measure voltage and resistance "everyday" at work but I can't remember the last time I measured current with my multimeter. (But I do "cheat" because the power supply on my bench shows voltage and current and I "keep an eye" on the current.)
