Mooshimeter - Wireless SmartPhone Multimetre

[remixed123]

This looks like an interesting product.

http://www.dragoninnovation.com/projects/34-mooshimeter

Measure 600V and 10A with 24 bit resolution through 50 meters of space and 6 months of time

The Mooshimeter makes multi-channel measurements possible in situations that are too fast, too slow, too sensitive, or too dangerous to use a traditional multimeter. And by harnessing your smartphone’s hardware, it does so at an insanely low price.

[Kryoclasm]

It is interesting.

[peter.mitchell]

whats the battery life?

[Jon86]

Cool product, same about the totally shit name.
"Oh yeah, my new Mooshimeter arrived today" 

Anyway, the '24-bit' resolution doesn't sound too convincing, sounds like he just stuck a 24-bit ADC in it and thought that every bit is going to be usable data...

[chickenHeadKnob]

Cool product, same about the totally shit name.
"Oh yeah, my new Mooshimeter arrived today" 

Anyway, the '24-bit' resolution doesn't sound too convincing, sounds like he just stuck a 24-bit ADC in it and thought that every bit is going to be usable data...

In their data sheet they claim >18 bits/ @ 125 samples per second, and 8khz fastest sample rate on two channels, so yeah something has to give.
Low burden voltage though. 

[Rasz]

Chris Gammell needs to be paid royalties for his prediction
'in ze future every meter and oscilloscope will work with tablets'

[con-f-use]

I got me one of the early bird specials as the dollar exchange-rate is nice and all. If I ever get one and there's still interest I will do a teardown/review.

[mikeselectricstuff]

Cool product, same about the totally shit name.
"Oh yeah, my new Mooshimeter arrived today" 

Anyway, the '24-bit' resolution doesn't sound too convincing, sounds like he just stuck a 24-bit ADC in it and thought that every bit is going to be usable data...

You will never get 24 real bits, and there will be a tradeoff between sample rate and resolution, but it's better than most DMMs in that price range. The hard part is getting the rest of the circuitry that accurate.

[con-f-use]

To be honest I don't care too much about the precision, as long as I get 3 digits out of it. But yes there's a lot that can go wrong. The prototype seems nice though.

What I don't like is that they put the SD-slot under the batteries. So you have get them out in order to change the SD-card. The fuse is also kinda hard to reach.

Input protection and board design seem reasonable, but not great:

Cool product, same about the totally shit name.
"Oh yeah, my new Mooshimeter arrived today" 

You think it's bad in English. But mushy only means soft to you. In German it's a totally different ball-park.

"Oh yeah, my new female genital meter arrived today!"

[mos6502]

You can actually buy something similar from Gossen:

Metrahit Ultra BT with Bluetooth: http://www.gossenmetrawatt.com/gmc/english/produkte/metrahitultra.htm

The Metralog App for Android: https://play.google.com/store/apps/details?id=de.ritso.gossenmetrawatt

[con-f-use]

You can actually buy something similar from Gossen:

For $800...

[mos6502]

You can actually buy something similar from Gossen:

For $800...

Well, it is a quality, high precision, 300,000 count multimeter, with traceable calibration, all the safety features, etc. Depends on what you need. On the other hand, you could whip something up similar with an AVR and a bluetooth modem for ~$10.

[con-f-use]

I was simply taking issue with the "something similar" part.

Also c'mon the parts for the Mooshimeter look like more than ten bucks. And by the time I'd have my shoehorned wip-up ready and an Android app, I'd invested way more than $75 of my time not to mention the dead prototypes on the way.

[psycho0815]

You think it's bad in English. But mushy only means soft to you. In German it's a totally different ball-park.

"Oh yeah, my new female genital meter arrived today!"

That's gonna make an awesome pickup-line:
"Hey Baby, soll ich dir mal mein Muschi-Meter zeigen?"
I might get one just because of this.
Otherwise, i don't exactly have a need for it. In the rare cases i could actually use a bt meter i just use one of my agilents with the BT Adapter.

[peter.mitchell]

I can't see a current shunt, and if i do see a shunt, i don't see kelvin connections to it...
I agree with the voltage socket and the cutout comment above.
How do you turn the thing off?
What is the battery life like?
If the battery life is meant to be as good as they want it to be, then you'll need to change the fuse & sd card more often, should have made the SDcard accessible via the side, not remove the battery like above commenter.

[con-f-use]

Current shunt resistor is the green smd comonent (first picture lower right corner). Turnoff is done over the connected tablet or via timeout. Bluetooth 4 has monitor capability to listen for wake-up signals.

[peter.mitchell]

Current shunt resistor is the green smd comonent (first picture lower right corner). Turnoff is done over the connected tablet or via timeout. Bluetooth 4 has monitor capability to listen for wake-up signals.

I see that, but i don't see any connections to it, or nearby vias, I guess its a 4 layer board and they've stuck the vias under it then.

I don't like the sound of that method of off/on, sounds like it could be very problematic...

[Dave]

In German it's a totally different ball-park.

"Oh yeah, my new female genital meter arrived today!"

The shape of the meter suddenly makes a whole lot of sense.

It's a neat idea, but the input protection seems dubious. I wouldn't trust that meter with any kind of high-energy circuit measurements.
The ultra long datalogging capability is also overhyped, because you are not going to leave your mobile phone sitting there for a week. It would be neat if the meter could log data onto its internal memory (microSD card slot, maybe?) and you could connect to it with your phone later and extract the data.

It may be ok as a second meter, but it's definitely not going to cut it as a general purpose meter. Having to play with your smartphone when doing measurements is too inconvenient, not to mention that the battery life of smartphones nowadays is appalling.

Also, would you consider borrowing your mooshimeter and phone to a colleague? What if your significant other decides to send you a quirky text while he's doing measurements with your phone?
Ok, then again, I wouldn't let colleagues borrow my standalone meters, either.

[psycho0815]

In German it's a totally different ball-park.

"Oh yeah, my new female genital meter arrived today!"

The shape of the meter suddenly makes a whole lot of sense.

It's a neat idea, but the input protection seems dubious. I wouldn't trust that meter with any kind of high-energy circuit measurements.
The ultra long datalogging capability is also overhyped, because you are not going to leave your mobile phone sitting there for a week. It would be neat if the meter could log data onto its internal memory (microSD card slot, maybe?) and you could connect to it with your phone later and extract the data.

It may be ok as a second meter, but it's definitely not going to cut it as a general purpose meter. Having to play with your smartphone when doing measurements is too inconvenient, not to mention that the battery life of smartphones nowadays is appalling.

Also, would you consider borrowing your mooshimeter and phone to a colleague? What if your significant other decides to send you a quirky text while he's doing measurements with your phone?
Ok, then again, I wouldn't let colleagues borrow my standalone meters, either.

Well youre college could use it with his own phone.
Apart from that i agree with you. Bluetooth capability is a nice gimmick on a normal Meter, but without a normal display it's basically a datalogger. Shure useful in some cases, but no replacement for a real dmm.
As for input protection, i don't know what kind of cat-rating they're shooting for, but given the concept of that thing, at least you propably won't hold it in your hand when it blows up...

[h1386343]

It's a neat idea, but the input protection seems dubious. I wouldn't trust that meter with any kind of high-energy circuit measurements.

They show it hooked up to a 400VDC source in the video, and measuring mains current in a few places.  Of course, accidentally connecting current mode across mains is another matter and I'd love to see that tested.

In the studio shot of the board it also looks like two rather large diodes are missing in the input protection area.  Maybe final version has more?

The ultra long datalogging capability is also overhyped, because you are not going to leave your mobile phone sitting there for a week. It would be neat if the meter could log data onto its internal memory (microSD card slot, maybe?) and you could connect to it with your phone later and extract the data.

It has a microSD card slot.  Streaming data out over BLE would be too slow though, you'll probably need to remove the card to retrieve data.

[Marco]

I see that, but i don't see any connections to it, or nearby vias

What of the vias near the input protection devices next to it?

[Dave]

They show it hooked up to a 400VDC source in the video, and measuring mains current in a few places.  Of course, accidentally connecting current mode across mains is another matter and I'd love to see that tested.

In the studio shot of the board it also looks like two rather large diodes are missing in the input protection area.  Maybe final version has more?

Every time Dave cracks opens a decent multimeter, you see several MOVs, a large PTC, HRC fuses, etc. Do you see any of this in this flimsy meter? That case also doesn't look like it would offer much protection if something suddenly decided to explode.

Well youre college could use it with his own phone.

Look at it this way: You need to make a quick measurement of something. Would you be willing to go to Google Play/iTunes App Store/whatever Windows phones have, find the correct app, download it, install it, open the app, pair your phone to the multimeter and then start taking measurements? It's a slap to the face of productivity.

Another thing I don't like:

Voltage
Up to 600V, DC or peak AC
Up to 420VAC RMS sinusoidal
Better than 0.5% accuracy DC
Better than 1.0% accuracy AC for harmonic content below 1kHz
>10 Megaohm input impedance

High Precision Voltage:
Up to 100mV with <15nV per count resolution
Up to 1.2V with <200nV per count resolution
>10 Megaohm input impedance

Current, Internal
Up to 10 Amps
20 µV / mA burden voltage (using factory fuse)
Less than 5 µA per count in 10 Amp scale
Better than 1% accuracy

Resistance
Better than 1% accuracy over 20 Ohms –  20 Megaohms

Frequency
Better than 1% accuracy up to 1kHz

Seriously, 1%? A shitty analog meter can do 0.5%. If they brag about 24-bits, it should be at least two orders of magnitude better.

Note on Provided Accuracies:

The accuracies and tolerances listed here are preliminary and conservative.  They do not include temperature compensation or factory calibration.

Expect these numbers to improve as we develop our calibration procedures.

Not convincing. Not convincing at all.

[mikeselectricstuff]

Re SD card, maybe the idea is you don't remove it but upload via BT.
Though SPI flash may be a better option as power draw would be lower - don't think you really need the huge capacity of SD for this.

[con-f-use]

You should address the concerns the community there [EEVBlog] has. Main points to this date are:

-How do you get to the logged data that's on the SD card? Streaming over
Bluetooth is slow and the SD card is hard to reach under the batteries
with no slot on the enclosure.
- How do you turn it on and off?
- "I don't see kelvin connections to the [current shunt]."
- Isn't the input protection a little flimsy? I don't see multiple MOVs, a large PTC, HRC fuses etc.
- What is the update rate? Don't you sacrafice accuracy at your aimed-for rate?
- 0.5% accuracy DC and 1.0% accuracy AC, FRQ and OHMs are not great and the " temperature compensation or factory calibration" argument is not very convincing.

Thanks [con-f-use]! I'll head over.
- Everything can be controlled via BLE.
- I do! Though it might be hard to see an inner layer trace from a photo...
- Our input protection is being tested to a CATIII 600V rating.
- There are many sample rates to choose from. The slower ones are lower noise than the faster ones, as expected.
- Stay tuned for an update!

[EricVanWyk]

Hi!  I'm one of the electrical engineers at Mooshim working on the Mooshimeter. 

Its been a hectic week trying to keep up with all the excitement, please forgive our latency!

Input Protection:
We are rating to CATIII 600V, and everything that entails under 61010.  Half of my background is medical sensors / therapy delivery, so I've had to make the transition from 60601. 

Kelvin Connections:
Immediately under the device, differential routing back to the converter on an inner layer.    Very hard to see from a photograph...

Datalogging:
No need to keep your phone paired for datalogging.  It'll log headless just fine.

Battery Life:
BLE draws very low current, and our math is showing multi-year standby time.

The Name: 
Now I know 13 words in German.