synFUZZsizer

[slacker]

how about cmos-ing the slacktave front end?

Good plan, I'll have a look at it, I've got some ideas to add a gate and or trigger output for firing envelope generators and stuff. I've also got a CMOS based LFO and sample and hold generator in my analogue synth, shouldn't be too hard convert it into something we can use here.

[artifus]

this is old and a bit messy but a start none the less... this lfo by any chance?


this needs tweaking (diodes?) as i find it a tad too triangular at low speeds (too much time spent fully on/fully off) , ok for high speed vibe-ness and wobble. layout for 49 not 69.

[slacker]

My LFO is based on Ken Stone's Psycho LFOs using CD40106s http://www.cgs.synth.net/modules/cgs21_super_psycho.html

Here's a quick schemo of the CMOSized slacktave input stage, I haven't built it but it should work. Probably needs some tweaks here and there. The idea is the gate out is high when you're playing and low when you're not, this could be used simply to drive a VCA or to control other modules. The trigger out gives a short high pulse when you start playing, this could be used to fire an envelope generator or sample and hold or clock a sequencer or ......

[artifus]

nice one, slacker, looks good. great idea on the gate and trigger outputs. another output could be taken after the transistor or first gate for a clean blend or to feed a fuzz.

*edit* on the subject of triggers a tunable twin t could be used to detect a particular note and trigger a filter sweep or sequence or... whatever. as in:

http://www.circuitstoday.com/whistle-to-beep-circuit

[Earthscum]

Since this is focusing on CMOS.... I feel obligated to post a link to Osamu Hoshuyama's work: http://www5b.biglobe.ne.jp/~houshu/synth/

He has a lot of CD4007 stuff. Lots of stuff in general.

ETA: I guess I should mention that between reading Osamu's writings, and R.G.'s, I came to the conclusion that for guitar "synth" stuff, the modules don't need to be quite accurate. Osamu has a lot of projects that explain "nonlinear from (x) to(y) points", or Works, but not precice, etc. However, I never have found anyone fixing these "issues". Basically what I've learned from both R.G. and Osamu is that mathematically perfect audio is blah, blech, lifeless. Really, I think my point is that we definitely don't need to worry so much about getting 1V/Oct. specs, just to ease the thinking process. Besides, running at 5V  leaves you with less than half the audio range, lol (although that's not hard to scale down to .5 or .4V/Oct or such).

I'm gonna work on getting my board cleared out today... that input stage looks very promising. Wouldn't be hard to make a mudule to put out pseudo-sine, triangle, and sawtooth waveforms, most likely on one chip. Not bad, 2 chips and a handfull of parts for a nearly complete input stage. Add the envelope module, and I can't think of anything else that couldn't be controlled from that box alone.

[artifus]

cool. some more links:

http://en.wikipedia.org/wiki/List_of_4000_series_integrated_circuits
http://www.allaboutcircuits.com/vol_4/chpt_3/index.html
google book preview page 205 is on the breadboard at the mo - mucho fun. very similar to:

Really, I think my point is that we definitely don't need to worry so much about getting 1V/Oct. specs...

hence the fuzz in synFUZZsizer. noisy, glitchy lofi fun, cheap and cheerful simple little circuits to play with.

[slacker]

The CMOSized slacktave thing doesn't seem to work too well. I'm not sure if it's because the third gate isn't working as a gate but in linear mode because of how it's connected to the filter or if I just need more gain, but at the minute it's not giving me a square wave.
Hopefully it will just be a case of having to use a couple more stages to really boost the signal up before the filter, if not I can always go back to the opamp one and add the gates and trigger to that.

[artifus]

i've yet to try your scheme slacker as i have limited breadboard real estate and have not been 'scoping outputs, just going by ear, but have been testing modules with just two gates of a 4049 (direct from gtr) into one 40106 gate with pull down resistor. previously used to just blast 'em with a 386. any high gain fuzz with enough output ought to be enough to get them going but heavy filtering obviously helps. my gtr has quite a high output with an unruly onboard preamp i often use, though have been testing mostly without, just throwing it in to hear what a bit of extra gain does every now and then - should maybe get the strat out, haven't touched it in a while, for more consistent share-able results.

are you more concerned with aural or visual results at the mo?

[slacker]

I haven't scoped it at all, it just doesn't sound square and it has very little sustain, sounds like a muddy overdrive. I'll have a play over Christmas, maybe try a few gates in series with some simpler filtering.

[garcho]

I love this thread.
I want to take some sequencer ideas a la Lunetta modules and use them as LFOs to alter tone and fuzz and what have you. Like an 8-bit tremolo with each bit adjustable, or a fuzz that sweeps through 10 bits of a band notch at adjustable speed. I made some arpeggiators with resistor ladders and throwing diodes and capacitors in random places made for some interesting tones and shapes. Could I use something like that as an LFO? Here's a link to some sound samples of the noise makers, about 2/3rds of the way down the page. How to translate these circuits into processing instead of generating tone?

[Earthscum]

I haven't scoped it at all, it just doesn't sound square and it has very little sustain, sounds like a muddy overdrive. I'll have a play over Christmas, maybe try a few gates in series with some simpler filtering.

Slacker, give the first 2 stages of this a shot in place of the first 2 in yours. This will also give a nice "Sine" out, as well... I posted it originally in the Saxxy thread, HERE. The last stage is just a buffer out so it can be used as a stand-alone unit. I should also note that I have used the first stage to drive (3 so far) different "bands", the first being a simple lowpass, the second and third were HP and a bandpass, just to test my idea. It actually worked pretty good once I tweaked it as far as separating notes, and I think it could be expanded even farther. I was using it to drive Schmitt triggers. Interesting thing being able to have 3 different processed voices on one stringed instrument. I was running lows to square, mids to something like a sawtooth, and highs were PWM. Anyways, enough babbling...

In case anyone wants to give it a shot, this works great for me... it's what I've been using to condition signals for square wave, PWM, Oct. downs, etc.

I actually use 27k instead of 22k for bass. If you still have tracking problems, try a 22nF cap for extra signal "dampening". I have had great success using this in front of Escebedo's  PWM with a 27k/22n with bass. Guitar worked ok with 22k/22n, so maybe 15n would've been good if I had one.

Anyways, have fun. Hope I can find one of these things... it's just too ugly and cool of a sound not to stomp on one!



ETA: You could pull a nice 10x boosted signal from the output of U1 C, and use one of the extra inverters as a buffer like the U1 A stage. Then you have buffered and boosted clean guitar signal to mix with. Want a nice "dub" sound? Pull a signal from the U1 B stage output and buffer it. There's your "Sine".

[Earthscum]

Slacker... Actually, Mark Hammer brought up one issue that you just noticed here. First, that 100k in front of the 'square out' isn't doing a whole lot of anything, given the impedance following it, BUT it should be doing something. If you tie the input to Vpos with a 1M or something, it will make the output always settle to ground (or close to) when there's no signal. Right now, I think it's just following the voltage of the preceeding stage.

[slacker]

Thanks for the tips I'll give your circuit a try sounds like it should do the job. I think you're right about the final inverter I'll try a pull down resistor.

[slacker]

Your circuit works great David, thanks for that. Here's what I've got on the breadboard at the minute, I hooked it up to a CD4024 divider and it drives that nicely with plenty of sustain. I haven't tried controlling anything with the gate but it flashes a LED, which shows that it works.

[Earthscum]

Been playing around a bit with it, just as you posted... working pretty good! One thing that I was concerned with was re-triggering, but that doesn't appear to be much of a problem. It'll take a little refinement, but I think this is going to be a solid base.

So, on the trigger issue: It appears to have no problem re-triggering without shutting off the gate, but I did notice on decay that the trigger begins to go high. I'm just using LED's at the moment.

The "Square Wave" isn't square, either... I scoped it and it appears to look like a rectified half-wave.

ETA: Was showering, getting ready to go do Christmas Eve stuff and had a brilliant idea. Put a cap across the 1M (say, 220p-560p) in the first stage, and turn the second and third stages into a schmitt trigger.

[garcho]

Bump this mutha

Anyone end up doing anything with this?

[jonasx26]

I've been fiddling with CMOS-octaver/synthy stuff.
The simple lunetta-style circuits often doesn't perform very good. Glitchy and unpredictable.
Maybe fun to mess around with on the breadboard. But IMHO not worth the time building into a permanent unit/module.

I WILL build a modular guitar"synth" some day. Though not all CMOS, nor simple or small.

[artifus]

i like glitchy and unpredictable and am still tinkering as and when i can.

*reference link dump*

http://rubidium.dyndns.org/cag/pdf/electrax.pdf

http://www.4shared.com/photo/ALQArBc0/CClark_synth1.html

http://experimentalistsanonymous.com/diy/Schematics/OOP%20Japanese%20Electronics%20Book/gtr-synth.gif

http://hammer.ampage.org/files/rocktave.pdf *last page - 109 - mod board only*

[egasimus]

Damn, gotta breadboard myself one of these when I get the time between medicine lectures and writing Web design tutorials...

[artifus]

zombie thread

not returned to this in a while but here are some notes from this period. cleaning up an old drive. these need to be blasted with squares on the inputs.

   



 


excuse the dodgy format. fink i've got some others somewhere - see if i can dig them out.

*edit* values - intended for experimentation. most c between 1n and 100n, sometimes 1u - 10u. r's are in the k up to the megs. label 'r' is variable. hard to hurt. breadboard away. check the links through out this thread for references.