We investigate the time-dependent behaviour of the variable-thickness bridges (VTB) and give expressions for the excess current, for the

term and for the upper frequency boundary of the Josephson effect. We discuss the validity of the results obtained for different weak links: cross-scribed bridges, proximity effect bridges and whiskers. On the basis of previous analysis the properties of memory element QUANTRON are studied. Then it is shown that the properties of many-terminal bridges allow one to combine high parameters of an externally-pumped down-converter and the simplicity of a self-pumped down-converter.