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Project Dwarf is a new observing campaign focused on the detection of substellar companions to low-mass (composed of late-type, subdwarf (sd) or/and white dwarf (WD) components) detached eclipsing binaries using minima timing. The crucial condition for the object selection for this campaign is possibility to determine times of the minima with high precision. This is naturally fullfilled for eclipsing binaries with deep and narrow minima or systems hosting a WD component showing fast ingress or egress.The observing project includes three groups of close eclipsing binaries indicating presence of substellar circum-binary components: (i)systems with K or/and M dwarf components(ii)systems with hot subdwarf (sd) and M dwarf components(iii)systems with white dwarf (WD) component(s). The sample of the eclipsing systems have orbital periods in range of 0.1 to almost 3 days and their brightness fits possibilities of small telescopes equipped with a low-end CCD camera and at least VRI filter set. Such kind of telescopes allow us to develop observing network including also amateur astronomers.

IU Persei (IU Per) is an eclipsing semi detached (SD) binary with pulsating component (oscillating eclipsing Algol - oEA). Using our ground base photometry in Johnson's B and V filters and INTEGRAL/OMC (Optical Monitoring Camera) data in V filter we introduce the model of this system. We determined the (O - C) diagram behavior. Moreover, the short term variations of the light curve were detected. Whats more, we obtained residua, by comparison of observational and synthetic light curves (LC), of which the detailed period analysis enabled to characterize and localize their source, that can be explained as the pulsation activity of the primary component. The secondary, less massive component, is beyond the instability belt on H-R diagram and fulfills its Roche lobe. The accreting primary component pulsates in modes typical for the δ Scuti stars.

Intermediate polars (IPs) represent more than 70% of all cataclysmic variables (CVs) detected by INTEGRAL in hard X-ray. Nevertheless, only a quarter of all known IPs have been detected in this spectral band. This fact can be related to the activity state of these object ruled by changes in the mass accretion rate.

Intermediate polars represent a major fraction of all cataclysmic variables detected by INTEGRAL in hard X-rays. Nevertheless, only 25% of all known intermediate polars have been was detected in hard X-rays. This fact can be related to the activity state of these close interacting binaries. Multi-frequency (optical to X-ray) investigation of intermediate polars is essential to understand the physical mechanisms responsible for the observed activity of these objects.

We can show that analysis of the (O-C) diagram is a powerful method of detecting new bodies in binary systems. For this purpose we need very symmetric minima with precisely determined shapes. In the case of good covering by observations with high time resolution, it is possible to determine the times of such minima with sufficient accuracy. In the case of V471 Tau, the (O-C) diagram gave us residua which can be explained by the presence of a fourth body with substellar mass in the system.