CMOS Flange-chorus-fuzz. Would this work?

[deadastronaut]

+1

its 8:05am, at the mo...

no pressure ha ha...........

[trat rödenback]

what shall i say??? i even signed up on diystompboxes just to say:

+1

exciting stuff!

[jasperoosthoek]

+2

And here's an augmented smiley. 

<-- Super smiley 

[slacker]

Cool

I might be wrong but wouldn't this need schmitt trigger invertors to work properly in the real world?
Not that I doubt Messrs Horowitz and Hill, you understand, but I don't remember seeing this sort of thing done with normal inverters.

[anchovie]

I'd have thought it would be OK as is - the XOR gate frequency doubler uses the same principle of an RC filter to create a small delay.

[slacker]

Good point never thought of that even though I've used it.

[earthtonesaudio]

Inverters biased semi-linearly will probably be more musically useful than schmitt triggers, because at low levels they will still let some signal through.  (By contrast the schmitt triggers will just stay off.)

[Derringer]

I was told there would be soundclips ?   

[Taylor]

Been playing with this a lot in simulation. The tricky thing is the biasing at the front end for some reason - it doesn't seem to bias right with the usual vref thing, and it needs to be dead center or else the later stages won't fire off.

I think I should have it built tonight, and I can perhaps record clips if it is interesting.

[Taylor]

Latest schem:

http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43941&g2_serialNumber=1

and simulation link:

http://tinyurl.com/33dwhwh

Note: the vref at the beginning is 2.5v, because the simulated inverters can only be run at 5v; this is half their supply voltage. In a real unit, with 9v logic chips, this should be 4.5v like the other reference points.

[Taylor]

Well, gentlemen, what we have here is a CMOS phaser.

It works like I had hoped, and it sounds pretty much like a standard phaser with distortion, though the phasing isn't super-deep. There are also some tremolo/gated fuzz sounds in here. Surprisingly (to me anyway), the mode with all of the stages mixed together sounds the most phasey, whereas the one that takes the last stage's output and combines it with the input (more analogous in topology to a regular phaser) sounds weaker.

The next step will be messing with the caps in the RC stages, to see if that makes much difference - it should change the max amount of shift per stage, so possibly increase the depth a bit.

I kind of don't think I'll manage to get clips together right now, but it really does sound like a phaser (with distortion) and that was the question mark for me. I don't know if this circuit is necessarily that interesting soundwise, but from the perspective of an unusual circuit design, I think it's interesting.

EDIT:

the phasing isn't super-deep

I take that back. Once I turned the lights out so the LDRs could work properly, and I adjusted the LFO to be deeper and slower, the sound was able to get pretty intense. I will try to do a quick etchable PCB layout so perhaps some other people can try it out if you feel inclined.

[maarten]

So funny, about those lights! Made the same mistake myself one time though. 
Cant you decrease distortion by some feedback over the inverters? You used a CD 4069 I presume? If I can find one, I''ll give it a try.

Maarten

[Taylor]

I actually used a buffered 4049 as that was the only hex inverter I had around. Once the circuit is a little more stable, I'll probably try a few different ones (unbuffered, Schmitt triggers, etc.).

I'm not sure if the effect will still work if we make the inverters operate more linearly. The effect is based on delaying the zero-crossing point, and then resetting to a square wave at each stage. I'm thinking, but could be wrong, that if the inverters stop acting digitally, the "phase shift" will disappear. But filtering on the end would be a good idea.

I also have been pondering getting rid of the optos in favor of a PWM oscillator controlling CMOS-switched resistors. Replacing the LDRs with a 40 cent IC would be nice. The only thing is that the LFO ends up being more complicated, so it might be a wash as far as parts count.

I keep waiting for one of "the elders" to come in here and show us that somebody did this 40 years ago... but until that time I'm feeling like this is a somewhat novel concept.

[frequencycentral]

Really interested it this. Certainly warrents further investigations. Did I ask for a very short soundclip already? Please!

[puretube]

Former German magazine "Elrad" had a fulll CMOS-inverter (3-chips) phaser in `83... (was it the december-issue?)
(it was the "linearized" inverters version), the variable Rs were made the "Badstone"-way...

[Taylor]

D'oh, I knew I wasn't that clever. Well, "ya know da Germans always make good stuff." so at least I'm in good company.

[Fuzz Aldryn]

Ja, ja, we Germans are clever people - maybe some Argentiniens too. Working with a mate on a pwm controlled CMOS Phaser. The LFO part is done: http://www.youtube.com/watch?v=4ab0OiB7shU Now it comes to the analog phaser part. We'll gonna try it first the way R.G. Keen come up with or we do it the way it was published in an Elektor article. We will see...  

[Hides-His-Eyes]

Relevant to my interests!

[puretube]

Ja, ja, we Germans are clever people - maybe some Argentiniens too. Working with a mate on a pwm controlled CMOS Phaser. The LFO part is done: http://www.youtube.com/watch?v=4ab0OiB7shU Now it comes to the analog phaser part. We'll gonna try it first the way R.G. Keen come up with or we do it the way it was published in an Elektor article. We will see...  

This...  


or what???

[Fuzz Aldryn]

Haha, didn't know of neither of posted threads. So thanks for your input.  First I got the idea then I started to search the web for further information and what first catched my eyes was this thread: http://www.diystompboxes.com/smfforum/index.php?topic=60144.0 Mr. Canel might remember well.  I was totally amazed by the demo vid he did about his phaser: http://www.youtube.com/watch?v=-7ZCtIuH1tk&feature=player_embedded