Putting the Mooshimeter to Sleep with a Bit of Mercury

If you haven’t heard of it, the Mooshimeter is a two channel multimeter that uses your smartphone as a display over Bluetooth 4.0. The ability to simultaneously monitor voltage and current is rather unique, and the fact that you aren’t physically tethered to the thing makes it ideal for use in hard to reach or even dangerous locations. The promotional material for the Mooshimeter shows users doing things like leaving the device inside the engine compartment of a car while they drive around and take readings about the vehicle’s electrical system.

Note the vertical orientation

All that sounds well and good, but at the end of the day, the Mooshimeter is probably not going to be your primary multimeter. It’s going to stay on a shelf until a task befitting its unique abilities comes along. Unfortunately, as [nop head] found, that can be a problem. Like many modern devices, the Mooshimeter doesn’t actually turn off. It just sits there draining its battery until you’re ready to use it. Which of course means that when you’re finally ready to pull the thing out and put it to use, you get a low battery warning and need to put new AAs in it. First World problems.

The fix for this thoroughly modern problem is delightfully old school: a mercury tilt switch.

Using a small spacer made of Kapton tape, [nop head] was able to isolate the battery contacts from the PCB itself. He then soldered the mercury switch in place between them, making sure to position the bulb vertically. When the Mooshimeter is right side up, the mercury flows down and bridges the contacts; but when the device is inverted the contact is broken and the batteries stop draining. He still has to remember to put the Mooshimeter face down when he’s done with it, but it’s better than dealing with constant dead batteries.

There was a lot of initial interest in the Mooshimeter when it was announced in 2014, but we’ve seen precious little of it since. It certainly seems neat, but perhaps it’s a bit too niche for its own good? If Mooshimeter fulfills a critical role in your tool set, let us know in the comments below.

32 thoughts on “Putting the Mooshimeter to Sleep with a Bit of Mercury

  1. I dunno if this was promotional but if so, sold! I never heard of these the first time around. Definitely going to get one, mostly for the automotive applications.

    I think I’m going to put a standard switch in there instead of a tilt switch though.

    1. Hmm, good point though there are some benefits having both fixed
      and tilt or shake wake-up with script or even adaptive timeout selective
      such as programmable mode power down
      ie. Slide switch (partly recessed) with 3 positions such as:-
      1. Power on
      2. Only power on when either tilted or shook logical And with visible light
      3. Power off

      With programmable power off sleep/mode options for each of
      the first two options, for example:-
      a. When in position 1 then enable timeouts on any of
      – none ie. No timeout but, maybe a low battery timeout
      – some select period of no comms or
      – no change in measurement by some minimum or
      – stays at zero or
      – no probes plugged in
      – other

      b. When in position 2 then enable timeouts to suit pattern of use
      with many permutations ie offer basic set modded to manage
      accidental on with no measurements or comms etc
      As this position is ‘soft’ and can thus be accidental could have
      short “beep on change” to alert the seasoned busy tech…

      c. A security mode re audit trail inspect, buff said about that ;-)

      There would be heaps of other options for operation if you had a
      Wake-up RTC, then you can craft the set of options with added
      variation for completely unattended modes in switch position 2
      and maybe a fully ‘silent’ mode of data collection in position 3

      Great fun, managing the potentials shouldn’t be any sort of a
      chore, as I’ve seen some grunts sadly complain prejudicially, it’s a
      a satisfying way to augment utility & increase income stream
      if you can find the right corporate partners or development agents…

      Cheers

    2. “I think I’m going to put a standard switch in there instead of a tilt switch though.”
      But without the mercury switch, how will you know when the car has flipped over?
      B^)

  2. I’ve got one, even if you don’t need the wireless capability, the power factor and logging capabilities are really nice especially for something that cheap. My solution to the power issue is to just put it into shipping mode when I’m done with it for a project.

    1. Yep, same here…bought it for the synchronous 2-channel measurement capabilities, care little for it being wireless :D
      And I also put it into shipping mode after using it, but even then it still slowly drains the batteries.

      Might end up plopping a small solar cell with a “power on” circuit in it, as whenever it’s not used, it’s in a case.

  3. I wanted the bluetooth features of the Mooshi but some regular meter features as well. I ended up buying the EEVBlog meter, but that has had its own huge set of fulfillment issues. Maybe I will actually receive it at some point.

    1. The deal breaker with the 121GW is that it cannot measure AC power. I’m going to guess they cheaped out using one ADC and multiplexing it, only to find that the multiplexing was too slow for AC power measurement to be anywhere near accurate.

  4. I think I’d rather have a nice Mercury-free mechanical switch, that didn’t require putting it upside down, but it’s still a cool hack.

    AFAIK they also have rolling ball switches filled with an inert gas. Probably needs a filter cap though.

    A hall sensor with a magnet that can roll to be near it or not might be an interesting tilt switch too.

    1. Ditto on a debounce circuit. I’m thinking that some roads testing (or other applications) will have a gravity based switch creating loads of transient power issues.

      1. Good point Adobe/Flash hater as a hack to the existing unit and I’m
        prompted to add have seen something similar a few years ago which
        used a combination of ptc & ntc resistors with suitable sized cap.
        Now thats a challenge for someone who loves “logistics of passives”.

        Of course for a new design possible to add all sorts of niceties such
        as the reed switch you mention and good point fortunately as its easiest
        to implement in current product :-)

  5. My best multimeter is >20 years old.
    And I’m not planning to buy a new one, because it’s still pretty good.
    Now remember the interfaces that multimeters had 20 years back, and whether you’ll find a software for that, that still runs on actual operating systems.
    Then imagine how well software for the Mooshimeter will work on devices 20 years in the future.

    1. So? Are you going to use your current phone 20 years from now? Or computer?

      It’s not like bluetooth is going away anytime soon, and the meter isn’t going to suddenly die. If someone wants to keep it working, it’s not going to be that hard.

      1. What if phones are using Blutetooth 5.6123940234843-A in 20 years time, and it’s not backwards compatible I think is the point he’s driving at. Or there will be no app support on the future OS of said phones/cranial implants. But I doubt the hardware of the meter will last that long anyway. So moot point?

        My go to multi-meter belonged to my grandfather. Though I do like the features… meh. I can work around it.

        1. Except BT is *already* 15-odd years old and still backwards compatible with v1, and there’s a *lot* of equipment using it. Even if the newest devices ditch BT entirely it’s going to be cheap and easy to track down hardware that will still talk to it.

  6. NEVER do this. Mercury switch becomes dangerous of broken. It contains about a thousand times more mercury than a typical fluorescent lamp.

    There are mercuryless tilt switches which use falling balls.

    1. “It contains about a thousand times more mercury than a typical fluorescent lamp”
      Actually, no. Look at how big that Hg switch is, there’s barely several times more of it then in a fluorescent light.
      Also the toxicity of metallic mercury is grossly overbloated, it’s the vapors that present an actual danger and that’s where fluorescent lights “win” over anything with metallic Hg in it.
      Just clean it up (and dispose of properly) if the thing breaks and you’ll be perfectly fine.

    2. After the recent HaD article about reed switches, I think one of those would be a viable alternative.
      The CAT rating could remain and a magnet could be on a lanyard off of a test lead.

  7. I have Mooshimeter and still love it. Using it almost weekly at work or at home when tinkering with some electronics.
    What I would like to suggest is to build in a reed switch in the Mooshimeter itself, and put a small magnet in the pouch it comes in. That way it will automatically switch off when you put it in its case. Batterylife is fairly good though; with a weekly usage I had to charge it only after a year.

  8. My Mooshimeter only gets used a few times a year but it is a lifesaver when I do use it. It’s small enough that I can carry it with me all the time and being able to put it in one room while flipping breakers/switches in another makes it perfect for “hey can you take a look at this” types of problems.

    I haven’t noticed it eating batteries that quickly but I do like the idea of a hardware off switch on all devices, the only problem I could think of with a mercury switch is bounce. How tolerant is the Mooshi to a couple quick power cycles, otherwise that’s a great little hack, being able to see the mercury through the clear case is fun as well.

  9. Actually, I was an early buyer of the Mooshi. And I love it even with its problems.
    Some are minor some are annoying but its a really capable device.
    It had a battery issue. One of the batches has a battery clip with burred edges that could cut the plastic wrapping of the AA cell and shorted it.
    It was discovered and corrected, was an easy repair with a needle file or some tape.
    On the HW side, it is well developed, properly tested and CAT rated hence the price.
    On the SW side it’s not so well, first versions of app lacked power factor and some other functions.
    Had several issues on after system updates, had to use two phones if one just refused to connect.
    On some sampling rates and averaging it had errors on the display it was a pain in the ass to use as a daily driver in the automotive repair field, I had to use it.
    On the plus side, the app can upgrade device FW ower Bluetooth and auto updates fw from the play store or whatever.
    I had only three or so app updates since it was shipped but it is pretty stable and usable by now.
    Continuity beep still horribly laggy. Btw used on Nexus devices on beta systems and so on. Would be nice to see more development because it would have so many possibilities like functions in sw or display options, bar graphs weightings, dB. scale and so on, it could be too hard but it needs more work done in SW.
    And i forgot to mention its construction is superb. dropped many times without any damage, used in dusty places but it just goes and its accurate as hell for its size and mobility.

    So Thumbs Up Mooshi just please go for it and don’t leave your product!

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