Author |
Message |
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
factus10
Joined: Jun 20, 2007 Posts: 158 Location: Buffalo, NY
|
Posted: Thu Mar 13, 2008 11:01 am Post subject:
|
|
|
Forrest's schematic is from a working model. |
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
Danno Gee Ray
Joined: Sep 25, 2005 Posts: 1351 Location: Telford, PA USA
|
Posted: Thu Mar 13, 2008 3:02 pm Post subject:
|
|
|
Is the schematic linkable / postable? |
|
Back to top
|
|
|
caress
Joined: Oct 08, 2007 Posts: 41 Location: brooklyn, ny
|
Posted: Thu Mar 13, 2008 3:35 pm Post subject:
|
|
|
the same chip is used in the 4ms atoner pedal. weird fuzzy sort-of-pitch-shifter...
http://www.4mspedals.com/atoner.php
you can also drop in a KA331 as well. |
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
caress
Joined: Oct 08, 2007 Posts: 41 Location: brooklyn, ny
|
Posted: Thu Mar 13, 2008 10:43 pm Post subject:
|
|
|
oh yeah 4151... same thing. |
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
Posted: Sat Apr 05, 2008 11:33 am Post subject:
|
|
|
well i tried building the foresst mims f/v converter and it basically doesnt work. i can slightly hear it changing the pitch on my vco when i feed it a line level musical track, but its not strong enough to fully change the pitch. maybe i need a level shifter on the input or output? or an amp?
could i use a transistor amp?
the mims design has an audio transformer on the input...but i could only get this working WITHOUT the transformer. questions-its a 1k, 8 ohm transformer. it has 3 in wires, and 2 outs. i figured coming in i would give one in gnd, and one in the hot signal and then out the 2 outs, one would be gnd and one would be hot signal. IS THIS HOW YOU USE AN AUDIO TRANSFORMER???
thanks--i will keep you posted _________________ -------------------------------------------- check out various dan music at: http://www.myspace.com/lossnyc
http://www.myspace.com/snazelle
http://www.soundclick.com/lossnyc.htm http://www.indie911.com/dan-snazelle |
|
Back to top
|
|
|
EdisonRex
Site Admin
Joined: Mar 07, 2007 Posts: 4579 Location: London, UK
Audio files: 172
|
Posted: Sat Apr 05, 2008 12:44 pm Post subject:
|
|
|
The transformer is very likely to be balanced.
Otherwise it wouldn't be there.
Makes sense, reject as much noise as you can and you won't end up sending the CV equivalent of 60Hz (or 120, or 180). _________________ Garret: It's so retro.
EGM: What does retro mean to you?
Parker: Like, old and outdated.
Home,My Studio,and another view |
|
Back to top
|
|
|
Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
Audio files: 11
|
Posted: Sat Apr 05, 2008 1:03 pm Post subject:
LM331 freq to volt chip?? |
|
|
Hey Loss,
Yes, there may be problems with the levels involved, but keep in mind that most commercial F-V chips are meant to work with very simple signals (sine or square) and won't work with complex signals like a guitar. I'm pretty sure the applications for these chips are things like deriving motor speed from simple encoders, so they're looking for a signal that is simple and doesn't change freq that quickly (exactly what we don't get from a musical input). If you're feeding a F-V chip a mixed musical track, there's no way it will give a meaningful output. Pitch (Frequency) to voltage conversion is a very tricky business, so while some of these chips are fun to play with, don't expect a properly tracking, top quality conversion from a simple circuit.
Tim (doesn't always track properly either) Servo |
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
|
Posted: Sat Apr 05, 2008 5:02 pm Post subject:
|
|
|
_________________ Jan
also .. could someone please turn down the thermostat a bit.
|
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
Posted: Sat Apr 05, 2008 5:44 pm Post subject:
|
|
|
a few things.
it seems to work better with the schematic from lm 331 datasheet than the forrest mims schematic. not sure why but....
anyway, the schematic in the data sheet works well with no transformer with line level signals (especially if they are distorted to the point of smoothing the edges) and i am now running the audio through a plug in that gets "sine" distortion....works very well with HIGHER notes on the guitar neck or LOUD microphone stuff.
this might work better with a noise gate pre.
i would be interested in other peoples experiences with f to v chips.
its hardly precise but it makes for very cool effects.
thanks _________________ -------------------------------------------- check out various dan music at: http://www.myspace.com/lossnyc
http://www.myspace.com/snazelle
http://www.soundclick.com/lossnyc.htm http://www.indie911.com/dan-snazelle |
|
Back to top
|
|
|
blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
|
Posted: Sat Apr 05, 2008 5:53 pm Post subject:
|
|
|
loss1234 wrote: | its hardly precise but it makes for very cool effects. |
In general for f->v to work you'll want a clean signal, and a noise gate is not a bad idea at all. You might want to try some low pass or bandpass filtering before the converter.
But indeed when it gets confused it's fun as well, as it goes wild sometimes and it listens at other times, the fun part for me is on the edge of recognition _________________ Jan
also .. could someone please turn down the thermostat a bit.
|
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
EdisonRex
Site Admin
Joined: Mar 07, 2007 Posts: 4579 Location: London, UK
Audio files: 172
|
Posted: Sun Apr 06, 2008 5:38 am Post subject:
|
|
|
The output of a frequency to voltage converter is, well, hopefully, control voltage, which is DC, which won't sound like much. You might try listening in on the signal at the input side of the LM331, for what it's worth.
I'd have thought that Jan's advice should be best practice with these things. _________________ Garret: It's so retro.
EGM: What does retro mean to you?
Parker: Like, old and outdated.
Home,My Studio,and another view |
|
Back to top
|
|
|
loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
Audio files: 41
|
|
Back to top
|
|
|
Rolbista
Joined: Nov 17, 2012 Posts: 23 Location: Poland
|
Posted: Wed Jun 25, 2014 7:08 am Post subject:
Filter |
|
|
Do you think that this chip would be good enough for tracking pitch of a keyboard (with a pretty steady singnal processed with a comparator) so that VCF's cutoff follows note played? |
|
Back to top
|
|
|
JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
|
Posted: Sun Jun 29, 2014 1:30 pm Post subject:
|
|
|
A lot of really good information about what this IC does and how it works internally is available in the datasheet. Here is one such datasheet. The specification itself for linearity looks very good. However, there are, like anything else, conditions that the circuit must meet in order to attain this linearity. One thing I saw was that for a F to V converter, the device expects a pulse train. This tells me that if you want to use random waveshape signals, you will need to convert them to glitch-free pulse trains before applying them to the circuit input. I'd also suggest that the amplitude of this pulse train be large and within the input specs of the device. Other issues to look at are going to be tracking speed and range. It is often the case the F to V converters are slower and lower frequencies.
Additionally, this device will output a voltage that is linear with respect to Hz, not octaves. Therefore, if you expect to use this in an expo type modular, you will need an additional chunk of circuit at the V output of the IC to convert the CV to expo.
In the end, the best way to tell whether this will work for your particular application is to get an IC and build. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
|
|
Back to top
|
|
|
prgdeltablues
Joined: Sep 25, 2006 Posts: 222 Location: UK
Audio files: 12
|
Posted: Tue Jul 01, 2014 2:30 am Post subject:
|
|
|
I've built an F- to-V circuit, using a different chip - LM2917. See my post:
http://electro-music.com/forum/topic-55362.html
As I noted, tracking isn't too bad, but the main problem is that the output drops down to 0 when the input signal stops, or drops below the threshold. You can gate the end of your signal of course, but that's quite abrupt, and when a new note starts, it has to climb up in pitch....The only way I can see to get round that would be to add in a delay, so the output of the chip was muted until it reached its proper level.
Peter |
|
Back to top
|
|
|
|