  Microfluidics has enabled a revolution in the manipulation of small volumes
of fluids. Controlling flows at larger scales and faster rates, or
\textit{macrofluidics}, has broad applications but involves the unique
complexities of inertial flow physics. We show how such effects are exploited
in a device proposed by Nikola Tesla that acts as a diode or valve whose
asymmetric internal geometry leads to direction-dependent fluidic resistance.
Systematic tests for steady forcing conditions reveal that diodicity turns on
abruptly at Reynolds number $\textrm{Re} \approx 200$ and is accompanied by
nonlinear pressure-flux scaling and flow instabilities, suggesting a
laminar-to-turbulent transition that is triggered at unusually low
$\textrm{Re}$. To assess performance for unsteady forcing, we devise a circuit
that functions as an AC-to-DC converter, rectifier or pump in which diodes
transform imposed oscillations into directed flow. Our results confirm Tesla's
conjecture that diodic performance is boosted for pulsatile flows. The
connections between diodicity, early turbulence and pulsatility uncovered here
can inform applications in fluidic mixing and pumping.
