Current measurement
We all know the ammeter with LCD or needle readout but in its original form it’s pretty useless as a recorder. Where in the past long-term current consumption was plotted on paper scrolls for the professor to analyse, today we have ADCs, DACs, USB and GUIs on our PCs and smartphones. A classic ammeter then is good for continuous current measurements even down to nano-amps.
Image: Qoitech

Pulsed, peak, non-periodic, oddball, Murphy and “rarely occurring’ currents are the domain of fast ADCs, software and data logging. Especially for IoT devices where current consumption is the specification, it's vital to be able to optimize battery endurance of the device. Hence the mention of “energy waste”, “sustainable solutions” and other fashionable “green” terms, on the Otii Arc box.

A black box it is
The Otii Arc box is both a power supply to the tested IoT device and a current and voltage measurement unit using ADCs and DACs. The Arc can be powered by USB from a laptop for portable and compact measurement set-ups, or by an external 9-V DC power supply (not included in my Demo kit).
The Arc box provides up to 5 V output voltage, in fact you can set the voltage to any value between almost zero and 5 volts using a slider control in the software. Current measurements are performed with a sample rate of 4 Ksps (kilosamples per seconds) for the range of 1 µA - 5 A.

Qoitech proudly state that their Otii Arc is a robust apparatus due to its aluminium casing. Also, that it is quiet (no fan), portable (power it via USB on your laptop) and easy to use (no buttons, all control is via the Otii PC app). Indeed you will look totally state of the art using your Arc box to test IoT devices out in the field!

All-in-one measurement unit

Otii Arc is a source measurement unit which Qoitech boldly say “replaces at least three instruments on your desktop”. It sources power as well as measures current and voltage concurrently, providing measurements in real time. All within limits of course.

Here are the Otii Arc physical specs:
  • Height: 4.8 cm
  • Width: 11 cm
  • Length: 24.5 cm
  • Weight: 480 g

Unlike a classic ammeter (okay there’s good auto-ranging ones around) there is no need for manually changing settings — the system is cable of measuring down to a few hundreds of nanoamps (nA) up to 5 amperes (A) in one go. The settings for the measurements you intend to perform are all done in a single window. I am showing it here.
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About Jan Buiting

Jan Buiting (1958) has been active in electronics and ways of expressing it since the age of 15. Attempts at educating Jan formally have so far yielded an F-class radio amateur license, an MA degree in English, a Tek Guru award, and various certificates in ele... >>

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