I setup and recorded this example of pulse width modulation using my Roland Juno-106. I started out playing an octave with the pulse width set to half way. Next I moved the pulse width up and down covering the full range possible. Eleven seconds into the recording I enabled the LFO on the pulse width and adjusted the speed of the modulation all the way up and then all the way down again. The picture shows the LFO in action. Notice that the LFO operates as a triangle, but with slight curves on each slope, which is probably a result of the analog circuitry. Here’s what it all sounded like.
Pulse Width Modulation