  In this paper, the realization of an inductance scale from 1~$\mu$H to 10~H
for frequencies ranging between 50~Hz to 20~kHz is presented. The scale is
realized directly from a series of resistance standards using a fully automated
synchronous sampling system. A careful systematic characterization of the
system shows that the lowest uncertainties, around 12~$\mu$H/H, are obtained
for inductances in the range from 10~mH to 100~mH at frequencies in the kHz
range. This new measurement system which was successfully evaluated during an
international comparison, provides a primary realization of the henry, directly
traceable to the quantum Hall effect. An additional key feature of this system
is its versatility. In addition to resistance-inductance (R-L) comparison, any
kind of impedances can be compared: R-R, R-C, L-L or C-C, giving this sampling
system a great potential of use in many laboratories around the world.
