For a practical verification of the proximity effect and Litz wire influences on coil resistance a set of experiments had been conducted. The results are tabulated in table 2. From the table two important conclusions can be made. First (blue box), due to the proximity effect resistance is increased by around two times. This experiment proves the possibility to reduce the proximity effect by simply increasing the spacing between the turns. Second (red box), Litz wire shows less performance on higher frequencies than magnetic wire with circular cross-section (note that frequencies of operation are nearly the same). In literature Litz-wire area of application is claimed to be about from 50KHz to 1-3MHz. Our experiments show that Litz-wire shows worse performance starting from ~2MHz.