Precision auto-ranging current meter (ammeter)

Here are some of the features of this instrument which sets it apart:

• Low noise zero-offset with 3-ranges (1mV output per nA/µA/mA)

• Low input burden voltage, high precision & bandwidth analog outputs

• Increased flexibility and usability with several input and output terminal options

• Fast auto-ranging capable

• Use standalone with a small OLED display or with a multimeter/oscilloscope

• Ultra fast range switching between any ranges (even nA to mA) without any glitching/bouncing of a mechanical switch

• Low Pass Filter mode – very useful to capture low noise signals on oscilloscopes

• Unidirectional mode – most used mode in measuring DC currents ranging from [0, 3.3A]

• Bidirectional mode – split supply biasing allows AC currents measurement ranging from [-1.65A, 1.65A]

• LiPo battery powered – long life and extended measurement range

• Auto-power-off

• Full digital control for power & range switching via touch pads

• OLED display option to read output with usable precision

• Datalogging possible via Bluetooth serial module or USB (use USB isolator, see guide)

• SAMD21 Cortex M0+ powered, change firmware to your needs

• Optional buzzer for audible feedback

• Current ranges output:

  • 0-3300 nA/µA/mA (Unidirectional mode)
  • +/- 0-1650 nA/µA/mA (Bidirectional mode)
  • Burden voltage:
  • 17µV/mA
  • 10µV/µA
  • 10µV/nA

• Output offset voltage¹: typically <10µV, max 50µV

• Maximum input voltage differential (see Safety): 33mV

• Accuracy:

  • +/-0.05% (µA, nA ranges)
  • +/-0.1% (mA range)

• Highest resolution (nA range):

  • 100pA (3.5digit meter)
  • 10pA (4.5 digit meter)
  • 1pA (5.5 digit meter)

• Cascaded ultra low offset/noise amplifiers with 100x output gain

  • Bandwidth: >300KHz (-3dB)

Sample no-load mA range comparison to µCurrent GOLD:

Sample measurement of a Moteino waking up and transmitting a RFM69 transceiver packet:

Kindly shared by MariusG, who has also designed the CurrentViewer

The model can be found on Thingiverse, and is also shared in this repository in SCAD parameter based format.