You guys are killing me...
yes, electrical harmonic frequencies, sound harmonic frequencies, light harmonic frequencies... all the same. BUT, since these energies are different, you have to condition the power to each one. You cannot apply a DC current to speaker, as it won't function. It requires AC to properly move the speaker engine. In a cell, you want DC, not AC, for reasons previously listed in other threads. You can use a music device to create your frequencies, but then rectify them to DC, and vuala, an easy freq gen. I am using a laptop as a signal generator right now, but its very ineffective until I can get some rectifiers and relays.
This is just such an easier setup than using a pwm imho because you can see the wave patterns of what you are sending, create loops, sequences, etc. And to make any changes requires your imagination, and not soldering different components in, 90% of the time.
Bzzz...