Substellar and stellar companions in eclipsing binaries

We present an extensive analysis of O-C diagrams constructed by previously published times of minima and updated by photometric observations carried out at Mythodea Observatory (Astrophysics Laboratory, Department of Physics, University of Patras). A two-companion model is attributed to the over-contact (W UMa type) binary system TZ Boo according to a Light-Time Effect (LITE), while in the case of the post-common envelope binary NSVS 14256825 a Jovian type circumbinary companion is the most plausible explanation of the apparent period variation.