<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On Apr 30, 2006, at 3:30 PM, Eric Brombaugh wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">Well, the PSoC is a 0V/5V device and it's DAC output is in that range. In the current system I boost gain by 2x and add an offset to make it +/-5V. That offset could come from a pot so you can dial in anything between +/-5V to 0/10V.</FONT></P> </BLOCKQUOTE></DIV><BR><DIV>So how do you select the waveform? Am I correct in assuming that you just have one output and some means to tell the chip which wave to make? If so, then your existing switching scheme might also be used to switch some external circuitry that, via some analog switches, selectively amplifies the wave and adds or subtracts DC bias to it, depending on which wave you have selected. This would give the desired bipolar as well as unipolar waves, all at the desired amplitudes.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>BTW, with regard to the filtering issue, I wasn't really referring to filtering that helps get rid of unwanted stuff at the major sharp wave transitions. I can understand how that would be helpful. I was referring to slew limiting that would reduce the audible effects of waveform stepping at low frequencies. This would have to be a filter with a much lower corner frequency. Your 5kHz filter, while useful for cleaning up the saw and square edges, won't help much in regard to the stepping issue at slow LFO rates, unfortunately. It'll be interesting to find out how that stepping is (or isn't) going to sound. If your DAC gives you 245 pitch steps per octave, that means that you have about 21.3 steps per semitone. If you put that into an unattenuated 1V/octave CV input on a VCO or a resonant filter, I'm guessing that it might be pretty easy to hear those steps at slow rates. Just a hunch -- I'd love to be proven wrong.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>MB</DIV></BODY></HTML>