Convert guitar signal into voltage

[jrc4558]

How to convert guitar signal into voltage to control the sweep of this:
http://www.geocities.com/tpe123/folkurban/fuzz/simplevcf.gif

That is the question.

Thank you in advance.

PS
Paste the link in the address line.

[Tim Escobedo]

Envelope follower is easiest way.

If you want the filter to follow the pitch you play, well, you're in for a uphill battle.

[jrc4558]

Envelope follower is easiest way.

If you want the filter to follow the pitch you play, well, you're in for a uphill battle.

I was thinking of something like that.  \ :twisted: /
What can help me in the uphill battle you think?

[Mark Hammer]

There are probably cheaper and easier ways to do it, but this one is all worked out and available, and that is the mono-pitch-to-voltage converter project from Bob Penfold that I have posted.  I made myself a board and stuffed it, but at the moment it looks like a balding Rastafarian hedgehog with twisted wires sticking out all over and no pots or jacks at the end of them, so I am unable to give a performance report.

You can also look on the net for Penfold's "Light Metal Effect" project/article.  That particular one uses much the same circuit for converting P-2-V, except that Penfold uses the derived voltage to have the modulating oscillator track the input frequency so that the interval spacing of the sum and difference signals in a ring-modulator is preserved as you move up and down the fretboard.  Clever idea, that.

[ExpAnonColin]

Yes... An envelope follower that basically lights up an LED (you could even use an audio LED meter) that then controls the resistance of the pot via an LDR.

-Colin

[puretube]

:?:

[Paul Marossy]

I tried to use a frequency to voltage converter chip with my guitar for a circuit idea that I had. Unfortunately, it's better suited for use with tachometers and stuff like that...

It would follow the higher frequencies, but for the low ones, it barely tracked and the signal levels were quite low compared to the higher ones. I should revisit that project sometime anyway. So many things to do and not enough time to do them.

[anyuser00]

I tried to use a frequency to voltage converter chip with my guitar for a circuit idea that I had. Unfortunately, it's better suited for use with tachometers and stuff like that...

It would follow the higher frequencies, but for the low ones, it barely tracked and the signal levels were quite low compared to the higher ones. I should revisit that project sometime anyway. So many things to do and not enough time to do them.

For that maybe you could use a frequency doubler on the front end of the circuit and adjust the output voltage accoardingly.

[Paul Marossy]

Hmm... that's an idea that no one has suggested before.

[anyuser00]

I bread-boarded a Freq-to-Volt. Convertor for a design projects.  It didn't work very well, but I think it's because I was lazy and didn't buffer the input.  It was either out of cookbook or directly off the AD Data Sheet.  I'll try to dig it out.  The purpose was to derive a control voltage based on frequency for a VCF.

[uncle boko]

Have a look at the EH Guitar synth on Mark Hammer's site hammer.ampage.org - the circuit is complicated but works - I built it in 1981!

[Rodgre]

I have a schematic somewhere that Paia sent me when i wanted to know if I could mod a Gnome synthesizer to be controlled by a guitar. There was ain interface circuit that was pretty simple that converted the guitar to a square wave I think. You could never dream of playing it polyphonically and having the Gnome do anything but burp, but it seemed promising.



Unfortunately, I never finished the Gnome and I never got the interface to work.

By the way, has anyone here ever built/used a Gnome?

[PlanetPatrol]

It seems that I remember a friend who had what I think was a Korg Ms 20 way back in the 80's. It had a section devoted to processing external audio and there was a frequency to voltage converter. When it was patched (with real patch cables) to the VCO and such, it actually worked, sort of. Albeit with a healthy lag of maybe 10 to 15 ms which made for quite a spongy feel when used with a metronome. You had to play way up on top of the beat. And strictly monophonic. In subsequent years, I too experimented with the LM9400 frequency to voltage chips with no success.

[vigilante397]

Welcome to the forum PlanetPatrol You just replied to a 15 year old thread. Probably won't get much involvement from the original poster

[anotherjim]

Sometimes I feel a need for thread that discusses such holy grails of audio engineering. Extracting the centre channel from stereo is another good one.

[duck_arse]

Sometimes I feel a need for thread that discusses such holy grails of audio engineering. Extracting the centre channel from stereo is another good one.

easily done by sitting on both sides of the room.

[antonis]

Sometimes I feel a need for thread that discusses such holy grails of audio engineering. Extracting the centre channel from stereo is another good one.

easily done by sitting on both sides of the room.

Piece of cake for split personality guys..
(although, they might have problem on quadraphonic systems..)

[Mark Hammer]

It seems that I remember a friend who had what I think was a Korg Ms 20 way back in the 80's. It had a section devoted to processing external audio and there was a frequency to voltage converter. When it was patched (with real patch cables) to the VCO and such, it actually worked, sort of. Albeit with a healthy lag of maybe 10 to 15 ms which made for quite a spongy feel when used with a metronome. You had to play way up on top of the beat. And strictly monophonic. In subsequent years, I too experimented with the LM9400 frequency to voltage chips with no success.

I was just watching a YT demo of the recent Behringer reissue of the MS-20 (the K-2) the other day, and the person doing the demo plugged in a guitar to the external signal processing input for P-2-V tracking.  The Behringer reissue tracked a little better than the original MS-20 used for comparison, but neither of them were particularly stellar.  Conceivably the original had some aged electro caps impacting on things.  There are far better units on the market these days, pitch-tracking being one of the things that digital does more reliably than analog.

[PlanetPatrol]

Oops! I meant Lm2907 instead of Lm9400. My bad.

[ElectricDruid]

I was just watching a YT demo of the recent Behringer reissue of the MS-20 (the K-2) the other day, and the person doing the demo plugged in a guitar to the external signal processing input for P-2-V tracking.  The Behringer reissue tracked a little better than the original MS-20 used for comparison, but neither of them were particularly stellar.  Conceivably the original had some aged electro caps impacting on things.  There are far better units on the market these days, pitch-tracking being one of the things that digital does more reliably than analog.

That's the sort of thing that I would have updated. I know, I know - "original circuitry" etc etc..blah blah. But who actually wants a P-2-V that doesn't track, really? Just replace that one little piece with something digital that works much better and then you'd have the control over the synth that the original designers wanted but weren't able to achieve with the technology available.