SparkFun offers the Mooshimeter, a multi-channel multimeter that harnesses a smartphone or tablet’s hardware as a wireless, high-resolution graphical display using Bluetooth^® 4.0. The Mooshimeter is able to safely measure 600 V at 10 A with 24-bit resolution from up to 50 meters away making multi-channel measurements possible in situations that are too fast, too slow, too sensitive, or too dangerous to use a traditional multimeter.

Traditional digital multimeters will only operate in a single mode at a time, meaning that to watch relationships in an active system multiple meters need to be used, but two channels means a relationship can be monitored. The Mooshimeter can measure any two of its three inputs, and the high-speed synchronized measurements allow for very fine measurement of power, including:

• Actual power usage: Measuring volts and amps on separate meters and then multiplying gives volt amps, which is watts only when the power factor is perfect.
• Power factor: How effectively is the power provided being used?
• Harmonic distortion: What sort of noise is being pushed back on to the lines?

Simultaneous voltage and current also allows more detail to be seen on how the system performs across its operational range.

Most multimeters have a front panel dominated by a numeric LCD display and a mode selection knob, but the Mooshimeter uses the hardware already commonly carried to provide features previously available only on much more expensive instruments and in a tiny, durable and affordable package. In the world of DMM’s, precision is usually given as a number of digits with the cheapest meters usually 3.5 digits and 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, but the Mooshimeter is built around a 24-bit ADC. This gives up to 7 digits to work with, though for most measurements expect 5 to 6 noise free digits. Combined with the graphing capability of the smartphone, this allows the smallest and most subtle signals to be picked up. With 24-bit resolution, the amplifier circuit can often be skipped and can measure things like heartbeat directly from the Mooshimeter.

The Mooshimeter also accepts a microSD card up to 32 GB and can log data stand alone for up to six months on a set of AA batteries. Just set up the sample rate through the associated iOS or Android app and walk away. The data is time stamped and saved either in binary or CSV.