thru-zero VCOs

andrewF · Posted: Wed Sep 12, 2007 2:12 am Post subject:

I have started building Mr Tillman's quadVCO.
On the schematic, 2 state outputs come from the comparators, which are described as 2 'free square waves' for waveshaping...etc'

My 1st thought was just to unity-buffer (is that a verb?...it is now) them and have some squarewave outputs.
but i know the benefits of asking first, anybody got some other ideas??

andrewF · Posted: Fri Sep 14, 2007 12:20 am Post subject:

this is one of those modules that makes you walk in circles whilst pointing upwards.
i found it a bit hard to build due to unfamiliar chips, unusual resistor values and 6 different voltages required (+/-15, +/-8, +/-5) but it works and it works very well...very different sound and response to inputs compared to the EN thru zero VCO.
You can see in the 'scope shots some jitter/noise on the waves. Mr Tillman states you should be careful with routing connections and he is quite correct. I found rerouting some wires greatly reduced noise, but more to do.
Haven't done anything with the surplus square waves yet, thought I'd just get it to work 1st.
Thanks D.Tillman for sharing such a great circuit.
Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

There are trimmers to set up the waveshapes, but i won't bother with doing that until this is installed in my modular - need to stop soldering and start panel-building.
with LFO input,
Posted Image, might have been reduced in size. Click Image to view fullscreen.

v-un-v · Posted: Fri Sep 14, 2007 1:49 am Post subject:

Groovy!

But what does it sound like Question

andrewF · Posted: Mon Sep 17, 2007 1:56 am Post subject:

not set up for handling audio on my pooter so its a wma file
30s of noise - using the SN-Voice to drive the tillman QVCO.
no filtering or fx, QVCO output direct into audio Cd burner.

tillvco.wma

Description:

Download (listen)

Filename:

tillvco.wma

Filesize:

315.99 KB

Downloaded:

328 Time(s)

janvanvolt · Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany

Peake · Posted: Mon Sep 17, 2007 4:45 pm Post subject:

Randaleem · Joined: May 17, 2007 Posts: 456 Location: Northern CA, USA

janvanvolt · Joined: Nov 24, 2005 Posts: 285 Location: Mainz, Germany

Same here, working on ~ 16 projects depending on parts availability and my order temper.

currently i am working part time on the klee design frontpanel.