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Measure PCB current without breaking the circuit


Current measurement is simple when you can break the circuit or clip a clamp around the current carrying conductor, but in the case of a multi-layer PCB this is not always practical or possible.


Aim-TTi have come up with a solution to this problem with the I-prober 520, which can measure current (dc up to 5MHz) simply by placing the insulated tip onto the current carrying conductor without making any electrical contact.

The I-prober measures the magnetic field that results from current flowing through the conductor, when the insulated tip is placed on the PCB's track (above the conductor), the same way as a conventional current loop probe does, by surrounding the conductor with high Mu material (like ferrite).


The positioning of the I-prober on the pcb is critical, as the signal is effected relative to the conductor, as the I-prober measures the magnetic field at a precise point on the board, so moving it away from the conductor reduces the measured signal, this is why the I-prober is known as a positional current probe.


Positional current probes are not new, however they were originally physically large and only suitable for measuring high current at low bandwidths, however Aim-TTi have come up with a patented miniaturised Fluxgate Magnetometer which is at the heart of the probe and is capable of measuring the field at a precise position, but it also has a much lower noise and wider bandwidth than a conventional Fluxgate Magnetometer.

The key performance and features of the I-prober 520 are:

  • Wide bandwidth of DC to 5MHz
  • Wide dynamic range of 10mA to 20A peak to peak
  • Low noise equivalent to <6mA rms
  • Rated to 300V CATII so ideal for measuring PSU circuits
  • Suitable for connection to any oscilloscope
  • Converts to a standard “closed magnetic circuit” current probe
  • Don’t need to break or surround the conductor
  • Observe and measure currents in PCB tracks directly
  • Minimal disturbance to circuit conditions through very
  • low insertion impedance and stray capacitance
  • Can observe currents flowing within ground planes
  • Useable on high voltage conductors and in high temperature areas

Aim-TTi have produced an introductory video, talking about the above features, but also goes into more details about the operational functionality:

  • Aim-TTi I-prober 520 Positional Current Probe (737-7192)
With a background in electronics and electrical engineering, with a keen eye on innovation and how things work.

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September 12, 2018 07:53

Very handy tool for PSU troubleshooting.
Worth it's money.

0 Votes
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