Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

Hi All,

I'm looking to mod my Polysix to get other waveforms for the MG (LFO). Right now, as you all know, the MG has a triangle waveform. I'd really like a square wave. I'd also like a ramp, but I think that a square wave ought to be a lot easier.

I looked at the schematic for the MG Oscillator section of KLM-367 but didn't see anything obvious where I could turn the triangle into a square. I'm not a master of understanding how these oscillators work, though, so I'm hoping that others might have some ideas.

My only idea was to insert an op-amp somewhere after Q1. I'd set the opamp with no feedback, so it would simply rail positive or rail negative as the current triangle waveform swings through zero.

I'm really hoping to not have to add an active component because it is so much easier simply to add a switch that shorts something, or adds a cap, or something like that.

Does anyone have any ideas?

Chip