VCO harmonizer?

[school]

would it work, in theory, to have a pitch-to-voltage converter such as this:http://www.musicfromouterspace.com/analogsynth/signaltogate.html
run in front of a VCO with a pot wired up to control the input voltage in order to create a lower harmonizing pitch?  you could only make the VCO go lower than your tone, but wouldnt it be cool? i dont have a thorough knowledge of VCO's at all, so i guess it might be possible to set one up to be able to go higher AND lower, but i dont know.  would this work?  id like to tack it on to my fuzz/noise/feedback/oscilator pedal.

[troubledtom]

have you ever herd of WWW.troubledvariance.com   ?
               this may or may not answer your Q
                    peace,
                         - tt :twisted:  :shock:  :idea:  :roll:  :wink:          :lol:  :wink:

[school]

i dont see how that could help me at all.

[troubledtom]

silly, your answer is yes i've been doing it for yrs your just 6-7 yr's behind me. it WILL work. but how , that's up to you.
  i used to ask z.vex can you do this or that and he'd say most likely but i'm not gnna design it for you. then i'd get hard at work.
    your idea is out of the box thinking and i like it
             peace and good luck on all your devices,
                     - tom pollock :wink:

[school]

ahhhh! alright.  I'm new to the world of VCO's, could you give me some links to datasheets....maybe? thanks!

[gez]

ahhhh! alright.  I'm new to the world of VCO's, could you give me some links to datasheets....maybe? thanks!

LM13700 data sheet.

[gez]

If you’re converting your guitar/whatever note into a voltage which controls an oscillator, then, unless the linearity is superb, you’re going to get a somewhat random/'out of tune' pitch.  Due to the inherent hysterisis found in many frequency-to-voltage converters it might be a little sluggish to rapid changes in input frequency too.  No reason why it can’t be higher in pitch than the input frequency though.

If you don’t want an element of randomness, then just build a typical octave type circuit (a 4046 design can give you different intervals)

[Arno van der Heijden]

What about a pitch-to-voltage-converter connected to a VCF? Anybody tried this?

[gez]

What about a pitch-to-voltage-converter connected to a VCF? Anybody tried this?

That's what this thread is about (as far as I know)!  

[Arno van der Heijden]

Hmmm.... :?  :roll:

I thought this thread was about voltage controlled oscillators, but I meant a voltage controlled filter, like the MS-20 style circuit.
That's not the same, is it? I'm new to these kind of circuits, so correct me if I'm wrong.

[gez]

Whoops, sorry Arno, I didn't see the VCF in your post. :oops:

If you did something like this it would be monophonic (no chords).  You'd get a change in tone across the fingerboard.  I don't think a wah-type filter would be appropriate (bit muddy on the lower strings) but a notch-type filter might be cool.

[StephenGiles]

School - look here:
http://ampage.org/hammer/files/EH-Guitar-Synth.ZIP

Don't let anyone fool you, building a frequency tracking VCO is no "simple" matter, and if you see any such circuit with that word in the description, forget it. I can promise you that the EH Guitar Synth works, designed before 1980, and I built the key elements around that time - on veroboard, (he braggs!) and may build it again one day. Lesser designs use a 555 and a 4046 (ever "unfolded a pen"?) for a "simple" but basically useless solution.

Also forget the MS20, quite useless in my experience.

Hard words - yes, but I hate to see folks wasting their time.
Stephen

[Arno van der Heijden]

Also forget the MS20, quite useless in my experience.

Hard words - yes, but I hate to see folks wasting their time.

Stephen, thanks for the advice. Do you mean the MS20 in general, or using it in combination with a pitch-to-voltage converter?

I was just considering building a MS20 style circuit on breadboard and was thinking about possible ways to control it.

[school]

wait, so if i just did it really simply, it would just be semi-random noise?

[gez]

wait, so if i just did it really simply, it would just be semi-random noise?

As Stephen said, there is no 'simply' about this. If I understood your first post correctly (I didn't check out the link, sorry), you'll get a Semi-random pitch *(as opposed to 'noise') with what you proposed.  If you want a note at a fixed interval to the one your instrument generates then you need to divide down your signal using flipflops or try a 4046 style circuit.  These circuits can be made to work quite well if you can find some way to counter the yodelling effect/poor tracking (not simple).

*edit: it won't actually be random, but may not necessarily have a pleasing relationship with the original note (earplugs on standby).

[school]

dissonance is good indeed! i'll do it!

[Arno van der Heijden]

Stephen,

Can you please elaborate a bit more on the MS20 style circuit? See my previous post in this thread....

[StephenGiles]

It yodelled a great deal, that's all I remember, not a patch on the EH Guitar Synth.
Stephen

[troubledtom]

dissonance is good indeed! i'll do it!

now you are on the right path. the dark side is creeping in your bones ,
i like it!
             peace,
                    -tt :twisted: