SNICster Waveshaper schematic question

zipzap

Hi Folks
For my next vco i want to start from a simple sawcore and then add the best waveshapers i can find.
This is one of them. http://home.earthlink.net/~ijfritz/sy_cir10.htm
It shows me again that many things are possible with opamps - if i understand them or not. All the shapers on this page look really cool!
Anyway, if you have a look at the schematic in the middle of the page, just labled SNICster, you see three otas used.
First of all, i want to substitute U1, a CA3080 with another LM13700. Got plenty of those. Should be no problem, i guess.
Next there´s U2a/b, a LM13700. He´s got great circuits there, but he hasn´t labled the pins. Where is R11, I2, R12, I3 going to?
I1-3 are propably for the controll in, but the resistors i´m not sure. The lin-diodes in?

zipzap · Posted: Wed Sep 06, 2006 6:13 am Post subject:

come on.

somebody must know that!
BTW, i just noticed with my other waveshaper if you drive the sineshaper to square up, fading from tri to saw gives you pwm from 50-99%. So all usual waveforms can be generated and morphed with this and the sineshaper. A must have!
cheers

bigtex · Posted: Wed Sep 06, 2006 12:17 pm Post subject:

So then you can morph between all waveshapes: tri, saw, sine, distorted sine, square, pwm? That sounds GREAT! Please post more detail about this, and maybe some sound clips! Very Happy

zipzap · Posted: Sat Sep 09, 2006 3:17 am Post subject:

Well, its just the stuff i did to Rays VCO. See my other vco vc-waveshaper thread.
But the difference is:
In those experiments i was just fading between saw and tri. Also nice. I don´t even know if it sounds much different than really morphing.
If it doesn´t i might just stay with it. It was done by sending the saw into an full wave rect...ifizier Confused

together with an offset (cv).
Saw above ground- saw out. Saw exactly around ground - tri.
And anything inbetween.
Squaring of those waves really sounds like pwm. Looking on the scope you see that it´s not that big range like real pwm, but it´s just the range one would realistically use for a good phasing squaresound.
I´ll record something.

zipzap · Posted: Mon Sep 11, 2006 3:39 am Post subject:

I just tested the difference between fading and morphing from tri to saw in the g2 dem. It´s a great difference. I need to build this.
Still the questions about the schematic remain...

Coriolis · Joined: Apr 11, 2005 Posts: 616 Location: Stilling, Denmark

Hmm...yeah, that is a bit difficult to read. R11 has 6.9V on it, but surely that can't be the supply voltage? That arrow pointing at U2 makes it look a bit like the wiper of a pot, but it's hard to be certain.

Best way to be sure is to join the sdiy mailing list and ask the man himself I guess!

C

Uncle Krunkus · Posted: Sat Sep 23, 2006 3:36 pm Post subject:

I'm about 98% sure that the 6V9 coming in through R11 and R13 goes to the diode biases. I'm pretty sure that the diode biases can be used to control the amount of offset when the amp "crosses over". It would make sense that this is important in a waveshaper. Why else would the 6V9 be derived from LM329s?