Hello all, still pretty new to Arduino and came across a confusing problem.
Wanting to just make sure I am starting off with the correct 5v straight out of the Arduino Uno board, I connected two jumper wires, one to Ground and one to the 5V VCC pin on my board.
However, on the multimeter I only read about 3.45V or so when I have the USB cable plugged into a wall wart. When I have the USB plugged in the USB port on the computer I get about 3.24V. Also when I plug into the 3.3V pin I get l about 2.2V. I actually have two Arduino Uno boards, and both behave the same way.
I wonder if a particular circuit I have built along the way may have damaged the board?
crtinkerer:
That should have a specific voltage when fully charged, correct?
Not really. There's a lot of variation.
OTOH if your meter is measuring about 2/3 of the real voltage you might be able to infer something. A new/charged battery should be above 1.25V. If you measure about 1V (or less), it's the meter.
Yes, I think it must be. After fully charging the AA rechargable battery I still only get .92V.
That must be the meter is not working properly?? Is it common for a multimeter to get damaged? This one was quite inexpensive, I just bought it at the local hardware store for about $20.
crtinkerer:
Yes, I think it must be. After fully charging the AA rechargable battery I still only get .92V.
That must be the meter is not working properly?? Is it common for a multimeter to get damaged? This one was quite inexpensive, I just bought it at the local hardware store for about $20.
It's kind of a crap shoot with an inexpensive meter like that. There are some decent multimeters out there for about three times that. I'd be surprised if the local hardware stocked them though.
come on, mine cost me about 20€, and gives accurate values . It is even able to give transistors hfe values (I admit I don't use it for that, but I tried 4 or 5 times, just to see, and it gave values in the datasheet fork ).
If you "just bought it" and it tells 3,45V instead of 5V (mine tells 4,96V ), it doesn't work and you should have it changed for free at your local hardware store.
Maybe it's time to change its battery ?
More expensive ones will be more precise, will allow you to measure smaller current and voltage value... some will read T° , or capacitance etc.... but even cheap multimeters read a 5V value with more than a 60% precision
I'd agree with alnath, check your battery first, also check to see if it has a fuse inside, you may have inadvertently popped it.
Also in ohms position see what the reading is when you short the probes, should be zero with a good battery. This will check if you have a lead failure.
Tom
It does give 0 ohms when the two leads are connected. As well, I saw that the fuse seems to be in tact when I changed the battery. The battery I put in wasn't 100% new so I will try that and see if it makes a difference.
Curiously, it seems to be reading around 67% of true voltage. The 5v output of arduino gives me 3.34V. 4 AA batteries in a battery holder, fully recharged gives around 3.76V, which used to be closer to 5.6 I believe.
if the display works well and tells good resistance values, I don't think the battery is too weak. The voltage measure doesn't need much current itself, the battery is mainly used for the display/backlight ....
maybe wires problems, contact quality.... or yes, multimeter broken, but as I said before, if it doesn't work, go get a new one for free
