Synchronized oscillators of the feedback type, possessing low-pass and band-pass filters in the loop, are considered. It is shown that these filters can, under certain conditions, be represented by time-delay networks.Stability and the pulling effect in a synchronized oscillator with a time-delay network in the loop are investigated analytically, graphically and with the help of an analogue. The corresponding non-linear hystero-differential equation is studied, and typical solutions are presented on the phase plane. Methods of improving the performance by the use of correcting circuits are also considered.