Mixed forced, parametric, and self-oscillations are considered if there is a delay in the elastic force in the system. A dynamic model is a friction self-oscillation system describing the frictional self-oscillations that occur in many technical systems for various purposes (metal-cutting machines, textile equipment, brakes and a number of other engineering objects). The operation of the system is supported by the energy source of limited power. For the analysis we used the method of straight linearization which is easier than the known methods of analysis of nonlinear systems, has no time-consuming and complex approximations of different orders, provides an opportunity to obtain the final design ratios regardless of the specific type and degree of nonlinearity, thus reducing labor costs and time by several orders of magnitude. By using this method, we obtained solutions of a nonlinear system of differential equations describing the system's motion. The equations of non-stationary and stationary movements are derived. To analyze the stability of stationary movements, the stability conditions based on the Routh-Hurwitz criteria are compiled. Calculations were performed to obtain information about the effect of delay on the oscillation modes. It is shown that the delay affects both the magnitude of the amplitude and the location of the amplitude-frequency curve in the frequency range depending on the magnitude of the delay, the amplitude curve is shifted to the region of lower frequencies. The stability of stationary oscillations depends both on the energy source characteristics and lag value. The interaction of the oscillating system and the energy source leads to a number of effects, both in the presence and absence of the lag. However, their course may be different depending on the lag value.