Fundamental Extractor PCB

[Andre]

Some time ago I build  the E&MM Harmony Generator which was discussed in this thread: http://www.diystompboxes.com/smfforum/index.php?topic=54424.0
I was not satisfied with the tracking of this circuit, so I decided to build a fundamental extractor to use in front of the harmony generator.
I used the extractor part of the Boss OC-2.
Although I have not used it with the harmony generator yet, I've tried it and the tracking is OK all over the fretboard and on different guitars.

I have done a PCB for it.
You can find it here:
http://www.xs4all.nl/~jvcn0028/pictures/Fundex_SCH.jpg
http://www.xs4all.nl/~jvcn0028/pictures/Fundex_PCB.jpg
http://www.xs4all.nl/~jvcn0028/pictures/Fundex_Layout.jpg
http://www.xs4all.nl/~jvcn0028/pictures/Fundex_Partlist.jpg

The PCB JPG is 300 dpi, if you use the right printer settings it will print in the correct size.
The circuit can also be used in front of circuits like tuners and guitar synths.

André

[markusw]

Cool! 
Thanks a lot!!

Regards,

Markus

[StephenGiles]

Are you sure¿

[Andre]

 

André

[kvb]

I've breadboarded the circuit and followed the schematic that you posted.

I'm getting output but things are rather noisy coming from the 324

also the schematic at freeinfo looks different.
http://www.freeinfosociety.com/electronics/schemview.php?id=135

my question is specifically about where the 4558's output is going

in the scheme you posted, from the junction of the two 33k resistors the lead appears to go to a positive (top) and negative (bottom) 324 input

from the end of the two 33k Rs, the lead seems to go straight to positive inputs of the first section of the 324

the freinfo schem shows the juction lead going to two negative ins
this would mean that the last section of the 324 is set up as a differential amp
so I figure that the freinfo schem is correct

I ran out of time to redo the leads (even though I knew it would only take a minute). I had already made the desicion to get some sleep.
I'll try it the other way when I get home from work.

Just a heads-up in case anyone else is trying this

[Andre]

Kevin,

I'm pretty sure my schematic is correct.
I used ExpressPCB to do the PCB and the schematic.

The PCB part of this application imports the schematic file, so you can do a design check.
It highlights the pins you need to connect.
Since the one I build using the PCB works fine, I think the schematic is OK.

Furthermore, although I do not completely understand the principle of this circuit,  I think that the 2 rightmost opamps are used as comperators.
One of them uses a high input to create a high output to reset the flipflop, the other one uses a low input to create a high output to set the flipflop.
So one of them needs to have the inputs reversed.

I hope this makes any sense 

EDIT: just found the original schematic: http://www.godiksennet.com/images/sch/Boss_OC2_Oktave.jpg
Proves my schematic to be correct.


André

[kvb]

OK      just so ya know - I'm not trying to be a d*ck or question your work
when I saw the freeinfo scheme, my first thought was that it was the questionable one

Then when things don't seem to work right, I'm left to wonder again. I tried twice - and even used a different bread board (one of mine has some questionable holes)

Oh well, looks like I'll have to check my voltages and start a debug thread

[Andre]

OK      just so ya know - I'm not trying to be a d*ck or question your work

No problem, it didn't feel like that to me 

I used Ben Milner's "Chopped OC-2" schematic, which is a copy of the original schematic with his mods added.
If I had used the freeinfo schematic I'd be probably still be debugging. 

Then when things don't seem to work right, I'm left to wonder again. I tried twice - and even used a different bread board (one of mine has some questionable holes)

Why don't you use my PCB, then at least I know that I did not do all the work for this PCB only for myself ? 

André

[SISKO]

Congratulations for your work

Now, let me get something. The flipflop produce a square wave at the ouput with a frequency equal to the fundamental, BUT we dont want that (do we?) because the square wave has a lot of harmonics that might trick the circuit wich is connected next (harmony generator, octaver, wahtever).
So, what is this circuit useful for? Its only to get a stable frequency response all over the fretboard?

[SISKO]

Well after studying it a bit, i realized that it produces pulses (wich is the most "compatible" signal with this circuits) at the ouput.

DOH! That happens to me because i speak before thinking.
Sorry

[loss1234]

this looks very useful

has anyone tried it with a circuit like a 4046?

thanks

[Mark Hammer]

Take a look at the P-2-V circuit from John Blacet here: http://www.loscha.com/miller/Polyphony-1978-10.pdf

[Taylor]

So, I've built this for use as the front end of the Harmony Generator, and it works and tracks, but the pulse wave doesn't shut up when I stop playing. Is it supposed to? The harmony generator derives its envelope from the input envelope, so having this constantly running oscillation is probably going to cause the HG to do the same.

Is this how the circuit is supposed to act, or do I have a problem somewhere?

[Andre]

I checked my extractor today, and it has no output when there's no input signal,
so it looks like something's wrong with your extractor.
I can measure some voltages if you want to.

[Taylor]

That would be great, thanks.

[StephenGiles]

The sine. output of a fundamental extractor should sound something like a flute, at least my EH one did.

[Taylor]

This thing doesn't put out a sine, AFAIK. Only a pulse. In any case, the output is fine, and it track, I just want it to be quiet when there's no input.

[Andre]

My extractor outputs an almost symmetrical squarewave.

These are the voltages I measured:

4558:
pin 1   4.9V       pin 8      9V
pin 2   4.9V       pin 7   4.9V
pin 3   4.6V       pin 6   4.9V
pin 4      0V       pin 5   4.6V

LM324:
pin 1   2.4V       pin 14   2.5V
pin 2   4.9V       pin 13   4.9V
pin 3   4.6V       pin 12   4.9V
pin 4      9V       pin 11     0V
pin 5   4.9V       pin 10     5V
pin 6   4.9V       pin 9    4.9V
pin 7   5.7V       pin 8    4.9V

4013:
pin 1                pin 14      9V
pin 2                pin 13   4.6V
pin 3                pin 12   4.6V
pin 4                pin 11     0V
pin 5                pin 10     2V
pin 6                pin 9       0V
pin 7      0V      pin 8    2.1V