The buzzing sound is normal, that is because at higher base resistance the coil and the transistor starts to self oscilate. I can do this with my SSG if I increase the base resistance to about 900 Ohms, then there is that high pitch sound, the wheel is not turning but the charging battery still charges up while the primary battery discharges. You can run your setup also this way, but that is not as efficient as when the wheel is turning