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justin3am
KVRAF
 
9998 posts since 7 May, 2006, from Southern California

Postby justin3am; Sat Oct 29, 2016 4:36 pm Re: justin3am's DIY eurorack adventure (ribbon controller update)

Yeah, I pulled the FSR out of an old keybed, where it was used as an aftertouch strip. I tried running it under the soft pot to use it as a pressure control but I ran into some problems. The soft pot needs to be on a solid surface to work the way it should and the extra layer added by the FSR makes it too squishy. Also the FSR requires a lot more pressure when it's under the soft pot.

A coworker who used to work for Alesis gave me some touch sensors which were used to for the ribbons on the Andromeda A6. This touch sensor has two wipers where the maximum resistance is at opposite ends of the ribbon. They said that it should be possible to get position and pressure with this ribbon. I guess I need to use one of the wipers more like a voltage divider, or something.

Honestly, I'm pretty dumb with all this stuff. I'm just lucky to have found a lot of online resources to help me a long the way. I figure it could be useful to put all I've learned in one place, so others can benefit.
Terrafractyl
KVRist
 
259 posts since 15 Nov, 2005, from Melbourne Australia

Postby Terrafractyl; Sat Oct 29, 2016 7:26 pm Re: justin3am's DIY eurorack adventure (ribbon controller update)

Hey cool Idea, and nice score on the Andromeda Sensors!

I have a 'Controller' panel planned with a decent sized Ribbon, and some FSR's, some Arcade buttons and a joystick, can't wait to get it finished actually, but yeah I kind of gave up trying to work out how to get a pressure output from the Ribbon!
In the end I built Ian Fritz's simple circuit that just has a gate and position out, which I did on stripboard and it works fine... but now the typical GAS has kicked in and you've got me all interested in trying to get pressure back in haha
Do you know what those sensors are exactly?
Hypnagog (Experimental Electronica) |
Terrafractyl (Psytrance) |Kinematic Records (Label)
deastman
KVRAF
 
6174 posts since 6 Aug, 2003, from San Francisco Bay Area

Postby deastman; Sat Oct 29, 2016 8:23 pm Re: justin3am's DIY eurorack adventure (ribbon controller update)

I haven't used mine in quite a while, but I don't recall the strip on the Andromeda having pressure.
Incomplete list of my gear: 110V AC to 12V DC 1.5A power supply (+ tip)
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justin3am
KVRAF
 
9998 posts since 7 May, 2006, from Southern California

Postby justin3am; Sat Oct 29, 2016 10:49 pm Re: justin3am's DIY eurorack adventure (ribbon controller update)

deastman wrote:I haven't used mine in quite a while, but I don't recall the strip on the Andromeda having pressure.


On the Andromeda, the extra pin wasn't used for pressure, but it was suggested that it could be used that way. I'm going to struggle to describe this... on a three-pin touch sensor, the point of contact closest to the the ground pin (?) is the where the ribbon is considered to be touched. Because of this, a normal position sensor will work like lowest-note priority on a monophonic keyboard, if you touch two positions at once. In order to get something that works like last-note priority, you need two resistive elements. This way if you hold a position and then touch another place on the ribbon with another finger, either above or below the first position, you will get a new voltage for the last position which was touched. I'm not even sure if it was implemented that way on the Andromeda (I've only used one once or twice) but my coworker said that was the intention. Then again, I have a tendency to infer a lot due to my own ignorance. :oops:

The ribbon was actually custom made for that product. From what I understand, FSRs and other touch sensors are made using a method very similar to making traces on a PCB. I wish it were a common part, as the sensors I have are longer than the width of my case.
deastman
KVRAF
 
6174 posts since 6 Aug, 2003, from San Francisco Bay Area

Postby deastman; Sun Oct 30, 2016 11:00 pm Re: justin3am's DIY eurorack adventure (ribbon controller update)

justin3am wrote:
deastman wrote:I haven't used mine in quite a while, but I don't recall the strip on the Andromeda having pressure.


On the Andromeda, the extra pin wasn't used for pressure, but it was suggested that it could be used that way. I'm going to struggle to describe this... on a three-pin touch sensor, the point of contact closest to the the ground pin (?) is the where the ribbon is considered to be touched. Because of this, a normal position sensor will work like lowest-note priority on a monophonic keyboard, if you touch two positions at once. In order to get something that works like last-note priority, you need two resistive elements. This way if you hold a position and then touch another place on the ribbon with another finger, either above or below the first position, you will get a new voltage for the last position which was touched. I'm not even sure if it was implemented that way on the Andromeda (I've only used one once or twice) but my coworker said that was the intention. Then again, I have a tendency to infer a lot due to my own ignorance. :oops:

The ribbon was actually custom made for that product. From what I understand, FSRs and other touch sensors are made using a method very similar to making traces on a PCB. I wish it were a common part, as the sensors I have are longer than the width of my case.

The Andromeda does have two separate regions on the touch strip (left and right sides). I think they just read the resistance in opposite directions relative to the center tap, so it can differentiate between the two sides. Or something like that. But I still don't see how that could be used for pressure. For pressure, they normally layer an FSR underneath a resistor strip so you can get both at the same time. I haven't looked at it in a while, but I'm pretty sure the Doepfer one works that way.
Incomplete list of my gear: 110V AC to 12V DC 1.5A power supply (+ tip)
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justin3am
KVRAF
 
9998 posts since 7 May, 2006, from Southern California

Postby justin3am; Mon Oct 31, 2016 7:27 am Re: justin3am's DIY eurorack adventure (ribbon controller update)

I'm also having trouble understanding how a position sensor can be used as a pressure sensor but I was given a schematic to try, so I'll test it out tonight.
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justin3am
KVRAF
 
9998 posts since 7 May, 2006, from Southern California

Postby justin3am; Sun Apr 30, 2017 9:15 pm Re: justin3am's DIY eurorack adventure (ribbon controller update)

I'll have to get the rest of the pictures from my camera but here is one from my phone.
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I still need to do the labels for the custom panel but after more than a year, I'm stoked to be so close to finishing this project!
I ended up using three pressure sensors independent of the ribbon sensor. Lots of fun to use them to control modulation amounts.
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justin3am
KVRAF
 
9998 posts since 7 May, 2006, from Southern California

Postby justin3am; Thu May 18, 2017 1:51 pm Re: justin3am's DIY eurorack adventure (ribbon controller update)

All done!
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I haven't had a chance to wipe the panels down so there is some grime on them. Other than that, I think the project came out pretty well. Especially considering this was my first big woodworking project in 15 years!

Here is a quick and dirty video I put together last night, to celebrate... nothing special.
http://www.youtube.com/watch?v=rccqT2uFwYY
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whyterabbyt
Beware the Quoth
 
24742 posts since 3 Sep, 2001, from R'lyeh Oceanic Amusement Park and Funfair

Postby whyterabbyt; Fri May 19, 2017 1:29 am Re: justin3am's DIY eurorack adventure (complete!)

Looks good, sir!

I finally sprung for a hot air station on account of this thread. Too many modules needing it these days (even one of the Sloth variants, FFS), finally decided I'd need to see if I could upgrade my soldering to 'silly microscopic' scale.
"The bearer of this signature is a genuine and authorised pope."
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justin3am
KVRAF
 
9998 posts since 7 May, 2006, from Southern California

Postby justin3am; Fri May 19, 2017 11:58 am Re: justin3am's DIY eurorack adventure (complete!)

Thanks! I'm really proud of how it came out. The project now moves on to the next phase and I will have some announcements about that soon.

The hot air rework station is mostly useful for ICs, particually TQFP and QFN packages. Actaully the only time I use my rework station is when I need to remove an IC. The key to successful SMD work is flux and solder wick. If you just glob solder all over the pins and then use solder wick to remove the excess, you'll be good. I rarely even use my magnifiers for TQFPs anymore. Just look up videos about drag soldering. It makes things super easy.
When it comes to placing resistors and and caps and other really tiny parts, the hot air will just blow them away. I describe the way I learned to mount those parts on the previous page, where I documented building an O_C module. If you have some super fine point tweezers, the technique isn't much different from installing through hole parts.

My advice, always buy extra surface mount resistors/caps and diodes. You will lose some and you will never find them again.
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whyterabbyt
Beware the Quoth
 
24742 posts since 3 Sep, 2001, from R'lyeh Oceanic Amusement Park and Funfair

Postby whyterabbyt; Sat May 20, 2017 3:53 am Re: justin3am's DIY eurorack adventure (complete!)

justin3am wrote:Thanks! I'm really proud of how it came out. The project now moves on to the next phase and I will have some announcements about that soon.

The hot air rework station is mostly useful for ICs, particually TQFP and QFN packages. Actaully the only time I use my rework station is when I need to remove an IC. The key to successful SMD work is flux and solder wick. If you just glob solder all over the pins and then use solder wick to remove the excess, you'll be good. I rarely even use my magnifiers for TQFPs anymore. Just look up videos about drag soldering. It makes things super easy.
When it comes to placing resistors and and caps and other really tiny parts, the hot air will just blow them away. I describe the way I learned to mount those parts on the previous page, where I documented building an O_C module. If you have some super fine point tweezers, the technique isn't much different from installing through hole parts.

My advice, always buy extra surface mount resistors/caps and diodes. You will lose some and you will never find them again.


Yeah, its a combined iron/hot air setup. My previous iron didnt have a precise temperature control/readout, so this is a step up on that side anyway. But Ive always found an iron a bugger to deal with removing/reseating anything multipin anyway, from IC sockets to .1" connectors, and more than once Ive been stuffed because I couldnt do that particularly cleanly. Was time to expand the capabilities a bit. Made sure I picked up good tweezers, wick etc at the same time.
"The bearer of this signature is a genuine and authorised pope."
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