Current Draw Measurement

Hi guys,

I’m trying to measure the current draw of my Arduino project, and I’ve found a link for it:

The theory behind is pretty simple, I just used a dc jack (as shown in the link attached) as an external supply. After that, I connected the multimeter in series to it.

However, I can’t get any reading from multimeter as the Arduino wasn’t even powered up when I connected my multimeter in such a way.

Is there anything that I’ve probably missed up? Or perhaps there’s other better way to do the current draw measurement?

Many thanks for helping :slight_smile:

ammeter.png

Make sure you are using the correct jacks on the DVM.
Your internal fuse may be bad or missing.
Make sure the DVM is set to DC amps maybe at the 200mA range.

LarryD:
Make sure you are using the correct jacks on the DVM.
Your internal fuse may be bad or missing.
Make sure the DVM is set to DC amps maybe at the 200mA range.

I'm currently using a 2.1mm dc jack as the external supply.
And I connected the same way as the tutorial link mentioned. (red probe of DVM goes to the power pin of dc jack, while black probe goes to the Vin of Arduino)

Is there anything else that I might be missed up, instead of internal fuse ?
Because I don't see any abnormality for my DVM :frowning:

It is easy to check the internal fuse.
Take it out and measure the resistance.

Show us an image of "your" setup.

.

Alright here you go :slight_smile:

The Arduino doesn’t seem to be powered up when I connected in this way.
However, when I tried to replace the DVM connection with just a jumper wire, the Arduino starts working.

Looks ok.
How about a image of the meter so we can see the controls and the jacks.
I still would give the likelihood to the fuse.

Does the red test point actually touch the metal in the proto board?
Same with the black?

As in the attachment, I’ve set my DVM to mA and DC mode.

And yes, I think it touches the metal in proto board.
I do tried to contact my probe directly to the dc jack (power pin) too, instead of measuring from the proto board. Unfortunately, it still seems to be not responding.

So you’re saying that my DVM fuse might be broken ? :o

Ok

Unfortunately beginners often blow these fuses all the time.
You should be able to remove the back somehow and then remove the fuse.
You might be able to indentify if the fuse element has vaporized just by looking at it.
Or
You can check the resistance of it.

If the fuse is gone, buy a package of them.

LarryD:
Ok

Unfortunately beginners often blow these fuses all the time.
You should be able to remove the back somehow and then remove the fuse.
You might be able to indentify if the fuse element has vaporized just by looking at it.
Or
You can check the resistance of it.

I got 1.5 mega ohm by measuring the fuse.

And for your information, my fuse rating is 0.5A/250V while the supply (dc adapter) rating is 12V 2A.

Is too much for the fuse to handle ?

The meter says right on the front "400mA max". So long as you are reasonably sure that your project doesn't draw more than 400mA then it doesn't matter what the power supply is capable of.

1.5M certainly seems to be a broken fuse.

MorganS:
The meter says right on the front "400mA max". So long as you are reasonably sure that your project doesn't draw more than 400mA then it doesn't matter what the power supply is capable of.

1.5M certainly seems to be a broken fuse.

Alright, got it. I will replace a new fuse after that.

Thanks for guiding :slight_smile:

Many thanks to LarryD too, appreciate for your patient replies