Little Bee Is an Open Source Current and Magnetic Field Probe

This tool effectively debugs and analyzes electronic devices, plus functions as a sensitive magnetic field probe and a current probe.

Cabe Atwell
3 years agoSensors

We must determine voltages and currents in our designs. It’s a given. Using an oscilloscope is simple. Current probes are cool but pricey at times. In walks an alternative − Little Bee, a low-cost, high-performance current and magnetic field probe from Weston Braun that's capable of effectively debugging and analyzing electronic devices.

The Little Bee is built around an Anisotropic Magnetic-Resistive (AMR) magnetic sensor, making its performance comparable to probes based on fluxgate magnetometers and those hybrid models combining AC current transformers with DC Hall effect sensors. It features a bandwidth that can be adjusted between 1 MHz and 10 MHz, an SMA output connector, connectivity to 1 MΩ impedance oscilloscope input, and it has automatic offset adjustment. Little Bee only requires one AA battery to operate! Neat.

This tool can function as a sensitive magnetic field probe. These types of probes can measure the current flowing through PCB trace and inductors. This is done by measuring generated magnetic fields. Even though non-intrusive current sensing doesn’t precisely measure current amplitude, it enables you to confirm circuit wavelength while identifying defects and short circuits. Little Bee’s magnetic field sensing has a 10 MHz DC bandwidth with a sensitivity of 0.2 Volts/Gauss, and its max field is +/- 6 Gauss. Its noise level is 32 mG p-p at 10 MHz bandwidth and 13 mG p-p at 1 MHz bandwidth.

The Little Bee also comes with a flux concentrator attachment that allows it to operate as a current probe, giving isolated measurements of a wire’s current. It’s able to measure currents over a wide bandwidth from DC to MHz. The current sensing has a 10 MHz DC bandwidth with a sensitivity of 0.25Volts/Amp, and its max current is +/- 5A. Its noise level is 25 mA p-p at 10 MHz bandwidth and 10 mA p-p at 1 Mhz bandwidth. The DC accuracy is +/- 15%, and insertion impedance is 100 nH in parallel with 70 0hms.

Those wishing to score a Little Bee of their own can now do so on Crowd Supply, where it's priced at $149. Braun plans to begin shipping in early April 2021.

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