Hi Alexander,

I have already measured RMS voltage on the secondary and it is around
14V. If I check it with the oscilloscope, I get Vpeak = 19.5V, Vrms =
13.7V. This is under approx 15mA load.

http://www.inetcat.org/stuff/transfo...ry-voltage.GIF

In front of 7805 I get 18V with 1.2V ripple:

http://www.inetcat.org/stuff/transfo...ed-voltage.GIF

Regards,
Alex