Mooshimeter: The Wireless Graphing Multimeter with Data Logging and Multichannel Simultaneous Sampling

Fun fact: None of these images are simulated.

Every Mooshimeter on this page is gathering real data in real life.

The Mooshimeter was born out of our frustrations as electrical engineers at the limitations of the “standard” digital multimeter.

Almost every digital multimeter will only let you use one mode at a time, meaning that to watch relationships in an active system you need to use multiple meters. Most have a front panel dominated by a numeric LCD display and a gigantic mode selection knob. And having the display mounted on the measurement hardware makes it very difficult to measure moving or enclosed systems, because the user must have clear line of sight to the meter to be able to read it.

Voltage and current waveforms of a laptop power brick

Over the last few years, many of us have started carrying big beautiful touchscreen radios in our pockets all the time. The Mooshimeter leverages the hardware you’re already carrying with you to provide features previously available only on much more expensive instruments in a tiny, durable package at an affordable price.

Why Wireless?

A wired meter forces you to get up close and personal with what you are measuring. This can be a mild inconvenience or downright dangerous. The wireless link provides you the freedom in your measurement to:

• Allow Mooshimeter to be bravely on the wrong side of a blast shield while you exercise the better part of valor.

Need to check the bus caps in your musical tesla coil?

Do it safely with a Mooshimeter

• Make measurements across water- or air-tight seals.

Installing the meter behind a watertight seal is no problem.

Green is system bus voltage, red shows bus current as the thrusters on the boat are pulsed.

• Realistically measure performance without having to chase after your robot.

Easily characterize the power characteristics of even the feistiest robots.

• Finally answer the question we’ve all had since we were 4: Does the light in the refrigerator actually turn off when I shut the door?

Read ambient light with a photoresistor and ambient temperature.

SPOILER ALERT - yes

Why Simultaneous Sampling?

One channel means you can monitor a state. Two channels means you can monitor a relationship. The Mooshimeter can simultaneously monitor any two of its three inputs. This allows very fine measurement.

The clearest win is measuring voltage and current, which in turn is power. The high-speed synchronized measurements allow for very fine measurement of power, including:

• True power (Using two unsynchronized meters will give you apparent power)
• Power Factor: How effectively are you using the power provided?
• Harmonic Distortion: What sort of noise is being pushed back on to the lines?

With voltage on the X axis and current on the Y, a desk fan is clearly a resistive load on high settings.

... and a reactive load on low settings

Simultaneous voltage and current also lets you see more detail on how your system performs across its operational range.

• Measure the performance of a battery under actual load conditions.
• A battery’s impedance is a much better indicator of its health and state of charge than voltage alone.
• Quickly characterize a system’s IV curve.

Plotting voltage on X and current on Y, quickly characterize your battery’s internal resistance by cycling the fan setting

24-bit Resolution

In the world of digital multimeters, resolution is usually given as a number of digits. The cheapest meters are usually 3.5 digits and carry a 12-bit ADC at their core. An entry level professional meter will usually be 4.5 digits and have a 16-bit ADC internally. The Mooshimeter reinvested the money saved by dropping the display and interface hardware back into the measurement components and is built around a 24-bit ADC. This gives you up to 7 digits to work with, though for most measurements expect 5-6 noise free digits. Combined with the graphing capability of your smartphone, this allows you to pick up the smallest and most subtle signals.

• Measure heartbeats like an EKG

No amplification here... just two brass chopsticks across the heart.

And a screencap for clarity.

• Pick up the output of an unamplified strain gauge across its entire range.

5uV/div vertical scale on the display

500uV/div vertical scale – without changing sampling range!

• Measure from -10A to 10A in 2uA steps.

Most multimeters add 1-10 millivolts / milliamp of burden voltage when measuring small currents! This drop can easily be enough to kick a USB device off bus or brown out a microcontroller.

The Mooshimeter’s current measurement mode introduces 20 microvolt/milliamp of burden voltage when measuring in 2uA steps over a full 10A range. Capture the sleep currents and the active currents of your digital circuits without autoranging.

And last but definitely not least, extreme voltage resolution allows you to...

• Measure arbitrarily large currents without rewiring

The Mooshimeter’s voltage resolution allows you to use the burden voltages already introduced by your system’s wiring to measure currents without disconnecting anything! Perfect for delicate digital systems and large power systems alike.

• Measure hundreds of amps with two alligator clips and a zip-tie.

Install in seconds without disconnecting the battery.

Can your meter capture a 200A startup transient from the passenger seat?

Why Logging?

The Mooshimeter accepts a microSD card up to 32GB and can log data for months. Just set up the sample rate through the app and walk away. The data is timestamped and saved either in binary or CSV. Life is short, you don’t have 12 hours to watch your battery charge.

Mooshimeter Technical Specifications:

Impatient engineering types will probably CTRL-F datasheet, or data sheet, and arrive here. We heard you, here is the datasheet for the Mooshimeter .