  We develop an approach to design, engineer, and measure band structures in a
synthetic crystal composed of electric circuit elements. Starting from the
nodal analysis of a circuit lattice in terms of currents and voltages, our
Laplacian formalism for synthetic matter allows us to investigate arbitrary
tight-binding models in terms of wave number resolved Laplacian eigenmodes,
yielding an admittance band structure of the circuit. For illustration, we
model and measure a honeycomb circuit featuring a Dirac cone admittance bulk
dispersion as well as flat band admittance edge modes at its bearded and zigzag
terminations. We further employ our circuit band analysis to measure a
topological phase transition in the topolectrical Su-Schrieffer-Heeger circuit.
