www.e-stim.net

I tried this by accident, and it felt so great I wrote it down so I could definitely go back to it!

However, I did not know to let the signals go out of sync and then bring the intensity back together.
As a consequence they continued to drift apart, which actually results in a nice randomness.
But I think to achieve HFO your method will likely work better.
Hmmm... must experiment!

And a couple weeks later I'm thinking this is DEFINITELY my go to set up, at least as far as the built in modes go!