  We study the proximity effect between the fully-gapped region of a
topological insulator in direct contact with an s-wave superconducting
electrode (STI) and the surrounding topological insulator flake (TI) in
Au/Bi$_{1.5}$Sb$_{0.5}$Te$_{1.7}$Se$_{1.3}$/Nb devices. The conductance spectra
of the devices show the presence of a large induced gap in the STI as well as
the induction of superconducting correlations in the normal part of the TI on
the order of the Thouless energy. The shape of the conductance modulation
around zero-energy varies between devices and can be explained by existing
theory of s-wave-induced superconductivity in SNN' (S is a superconductor, N a
superconducting proximized material and N' is a normal metal) devices. All the
conductance spectra show a conductance dip at the induced gap of the STI.
