  A flexible and low-cost device for eddy current non-destructive testing made
of off-the-shelf components is described. The proposed system is compact and
easy to operate, and it consists of a dual H-bridge stepper motor driver, a
coil winded in-house on an additively manufactured support, a tunnel
magnetoresistance sensor, and a data generation/acquisition module. For the
latter, two different commercial devices have been used, and both setups have
been then tested on a benchmark sample to detect small artificial cracks. The
system can flexibly generate the square pulse or square wave with tunable
duration and frequency, as well as pseudo-noise binary waveforms that are here
used in combination with pulse-compression to increase the inspection
sensitivity with respect to standard pulsed eddy current testing. A benchmark
sample was analysed, and all the defects were correctly located, demonstrating
the good detection capability of the sensor. This was achieved by assembling a
very low-cost handy device, which can be further improved in portability and
performances with the use of different off-the-shelf components, and that can
be easily integrated with single-board PC, paving the way for future
developments in this field.
