I've run into limitations with my cheapo $30 multimeter when I needed to measure custom Arduino circuit power draw over time (in microAmps) over period of time (developing battery powered sensor).
So I'm shopping for a great multimeter, preferably around $250 
I've read a lot about Fluke 87-V, which seems like a dream, only it's a bit expensive ($330 new, I can get Oscilloscope for that money!) and it seems to be geared mostly to AC work, and I don't give rat's behind about True RMS feature
So I'm thinking to pull trigger on a used Fluke on eBay, but wanted to check here first if there's anything better you might recommend?
Something that would suit better for DC and microprocessor work, can measure microAmps with high precision and also can log stats over time (so I can find out average current of circuit i.e. it sleeps, wakes up, sends signal and goes back to sleep).
You might think about using a Hall Effect current sensor with an arduino. Log to an FRAM chip or a serial port with a laptop connected. You could build something like that for < $50.
cptdondo:
You might think about using a Hall Effect current sensor with an arduino. Log to an FRAM chip or a serial port with a laptop connected. You could build something like that for < $50.
The problem isn't just in measuring current (you could put a 1 ohm resistor in the power wire and measure the voltage drop across it for $0.05). The problem is in the "microamps" part.
All Multimeters suffer somewhat when trying to read small currents in the micro and nano amp range due to 'burden voltage', they simply are not optimized for this range of current measurements.
A very nice solution is the get a amplified current sensor that any multimeter can then read to obtain such measurements. Adafruit carries a very nice one that David Jones designed.
Lefty
retrolefty:
A very nice solution is the get a amplified current sensor that any multimeter can then read to obtain such measurements. Adafruit carries a very nice one that David Jones designed.Lefty
Wow, that's really cool! Exactly what I need, thanks man! Ordering one!
Would reading voltage have the same affect? This morning in doing some troubleshooting (on only my second day as an Arduino hobbyist) I found that though I should 1.7 vdc coming out of my pin 13 LED output my fluke wouldn't read it. Ultimately I got blink to work but never was able to read the voltage.
I found that though I should 1.7 vdc coming out of my pin 13 LED output
Which reference do you use?
Pin13 vs. GND should be either Vcc ( about 5V on many Arduinos ) or 0V, if it's set to OUTPUT.
If Pin13 blinks ( too fast ) you can see anything in between.
Some time ago (last couple of years?) Circuit Cellar magazine had an article on building one of those devices that allowed you to measure way down into pico amps or something like that. Might check out that article too. Start with this article Measuring small currents