Rockdude discusses precision rectifiers and positional sens

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Re: Rockdude discusses precision rectifiers and positional s

Postby rockdude » Thu May 27, 2010 5:25 pm

mackanov, can you record some audio or video using the positional sensing feature? I know that you've got inconsistent results in the higher velocities, but maybe you could do a demo when playing lower velocities?
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Re: Rockdude discusses precision rectifiers and positional s

Postby mackanov » Fri May 28, 2010 4:18 pm

My rolls are lame (I'm a guitar player :lol: ) but here you go. Remember my snare is using a foam "cylinder" not very cylindrical and the foam is way too soft. It tends to get confused on rolls, but detects very well when playing slower.
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Re: Rockdudes attemt to build a precision rectifier

Postby Ken Forgettable » Fri Jun 04, 2010 8:21 pm

For those people who get two distinct positions this is what is happening:
OscEdgeReflection.GIF
You whack the head and the wave travels to the sensor.
The same wave bounces off the edge (rim) too.
Hitting closer towards the edge will eventually cause the two waves to converge into one fat ripple.

The effect of this is an apparent sudden decrease in frequency as seen by the sensor.

If you play with the stereo balance of this audio file you will see this problem is not unsurmountable 8-)
ps_scopeMIX.mp3

NB. Be clear - this is frequency to pitch not a velocity to pitch mapping - this is a 3D drum...
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Re: Rockdudes attemt to build a precision rectifier

Postby rockdude » Fri Jun 04, 2010 8:29 pm

Ken Forgettable wrote:For those people who get two distinct positions this is what is happening:
OscEdgeReflection.GIF
You whack the head and the wave travels to the sensor.
The same wave bounces off the edge (rim) too.
Hitting closer towards the edge will eventually cause the two waves to converge into one fat ripple.

The effect of this is an apparent sudden decrease in frequency as seen by the sensor.

If you play with the stereo balance of this audio file you will see this problem is not unsurmountable 8-)
ps_scopeMIX.mp3

NB. Be clear - this is frequency to pitch not a velocity to pitch mapping - this is a 3D drum...


Good explanation! I'm trying to surf those waves.
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Re: Rockdude discusses precision rectifiers and positional s

Postby dmitri » Fri Jun 04, 2010 8:41 pm

mackanov wrote:It tends to get confused on rolls

I know why it is happening and have ideas how to correct it in upcoming firmware versions.
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Re: Rockdude discusses precision rectifiers and positional s

Postby Ken Forgettable » Fri Jun 04, 2010 9:07 pm

dmitri wrote:
mackanov wrote:It tends to get confused on rolls

I know why it is happening and have ideas how to correct it in upcoming firmware versions.
Rolls 'ave a tendency to tension the -head and !pre-stresses the brain ^don't !they.
(Hey I suddenly lapsed into phonic programming. Very disturbing).

Try this (snigger):
OnARoll.mp3
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Re: Rockdude discusses precision rectifiers and positional s

Postby mackanov » Mon Jun 07, 2010 1:23 pm

dmitri wrote:
mackanov wrote:It tends to get confused on rolls

I know why it is happening and have ideas how to correct it in upcoming firmware versions.


I don't know when I'll be able to get the new processor with the secure bootloader, so for now I'll have to live with this. :)
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Re: Rockdude discusses precision rectifiers and positional s

Postby rockdude » Fri Jan 02, 2015 11:29 pm

Ok, reviving my old positional sensing and precision rectifying-thread now that I'm ready again to attempt building one.

Image

I've spent some time trying to track down the components I need for the build.
Here's links to the components I plan to buy (please correct me if I'm wrong, I really don't know much about this stuff):

OPAMP:
LMC6034 Op AMP *2
http://uk.farnell.com/national-semicond ... tt=LMC6034

Can any other OPAMP in this link be used instead so that I can order everything from one place?
http://www.electrokit.com/operationsforstarkare.c1385/1
Or maybe you can send me some of your spare ones ignotus?


RESISTORS:
Resistor 100K *1
http://www.electrokit.com/motstand-100k.41389

Resistor 15K *2
http://www.electrokit.com/motstand-15k.41379

Resistor 10K *1
http://www.electrokit.com/motstand-10k.41377

Resistor 12K *1
http://www.electrokit.com/motstand-12k.41378

Resistor 330ohm *1
http://www.electrokit.com/motstand-330r.41359

CAPASITORS:
Capasitor 1uF *1
http://www.electrokit.com/keramisk-mlcc ... -5mm.51696

Capasitor 100nF *1
http://www.electrokit.com/keramisk-100n ... iell.45633

Capasitor 1nF *2
http://www.electrokit.com/keramisk-1nf- ... 54mm.41768

DIODE:
Diode 1N4148 *1
http://www.electrokit.com/1n4148.41532

I guess that's all I need (except for the jack inputs? I won't order the parts before anyone has confirmed that I have found the right components. I noticed the schematic says +5v at some places and I don't really know what that means or if I need something more there? I also don't know what the red numbers around the OPAMPS means?

I found an old board that I've practiced my soldering skills on earlier that would work just fine to build the precision rectifier on? I just need to desolder the components from it. Or do I need a bigger one?
Image
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Re: Rockdude discusses precision rectifiers and positional s

Postby ignotus » Sat Jan 03, 2015 1:36 pm

On Monday I'll have a look and make a drawing for you so you can see how to connect everything. That board will more than enough.
If it ain't broken... fix it until it is.
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Re: Rockdude discusses precision rectifiers and positional s

Postby rockdude » Sun Jan 04, 2015 10:06 am

ignotus wrote:On Monday I'll have a look and make a drawing for you so you can see how to connect everything. That board will more than enough.

Thanks! Looking forward to your drawing. Until then I'll try to read up on reading electronic schematics :oops:

I have a few questions about dimitris schematic:

Image
Are all the nets/lines with this symbol supposed to be connected together and go to ground somewhere?

Image
And all the nets with this symbol are supposed to connect together and go to power somewhere? To power on my synthex board or somewhere else?

Image
Is this some kind of isolated part of the schematic? It's not connected to the rest as far as I can see...more than the 5v power and ground.

Image
This is the opamps pins if I'm not wrong. Found the pdf for it. Are the numbers pointing out from the opamp on dmitris schematic the corresponding pin on the ompamp like I've highlighted to the left?

Im curios to see how this board is connected to my Synthex 3.1 board. Or maybe it's a separate unit that connects only to the jack input I'm planning to use positional sensing on. I'll wait curiously until monday :)
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