In my driving circuit i use the capacitor across the circuit... the circuit is limited to 200mA to load... the switching frequency is 4khz....
i used the electrolatic capacitor of 22uF... which occupies more space....
the problem is when i replace the capacitor with eq. of 22uf ceramic type (to reduce the space) , the circiut becomes more noisy(sound).................
The only components that have audible noise are ferrite and other magnetic components, as the changing flux actually changes the shape of the item which then acts as a little loudspeaker. So your two capacitors are changing the currents around the circuit to change the magnetic effect and hence the noise. a 22MF CERAMIC capacitor?
Frank