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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
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Posted: Mon Feb 18, 2013 6:17 pm Post subject:
SynthBend Controller System |
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I am currently building a large synthesizer controller system which will include a very full featured volt/octave keyboard, an upgraded appendage ribbon controller module, and a wealth of other modulation controls. Force Sensitive Resistors are also being incorporated into a number of the modules. Details can be found here:
http://www.electronicpeasant.com/projects/synthbend/synthbend.html
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Mon Feb 18, 2013 6:46 pm Post subject:
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138 banana jacks.
Awesome work |
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Benjamin AM
Joined: Nov 04, 2010 Posts: 83 Location: Boise
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Posted: Wed Feb 20, 2013 7:12 am Post subject:
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Nice work!
I've been throwing around the idea of installing an FSR circuit underneath my appendage controller. I was curious if you have built and tested the circuit that you have drawn up on your website. My main concern is that that there may be a "dead spot" or area of dulled response in the middle of the controller. This concern arises because I noticed that there are only two small sensors for the length of your keyboard. I've never experimented with these FSR sensors so I am unsure if this is a legitimate concern. With that said, I am sure that there is an easy way to compensate for a sensitivity droop if this problem does exist. Although, I haven't spent much time trying to derive meaning from the schematic, I would assume you have done this. I can't wait to try this out. Have any suggestion to which sensor to purchase?
-Ben |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Wed Feb 20, 2013 9:25 am Post subject:
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Benjamin AM wrote: | Nice work!
I've been throwing around the idea of installing an FSR circuit underneath my appendage controller. I was curious if you have built and tested the circuit that you have drawn up on your website. My main concern is that that there may be a "dead spot" or area of dulled response in the middle of the controller. This concern arises because I noticed that there are only two small sensors for the length of your keyboard. I've never experimented with these FSR sensors so I am unsure if this is a legitimate concern. With that said, I am sure that there is an easy way to compensate for a sensitivity droop if this problem does exist. Although, I haven't spent much time trying to derive meaning from the schematic, I would assume you have done this. I can't wait to try this out. Have any suggestion to which sensor to purchase?
-Ben |
Hi Ben,
The circuit on my website has been breadboarded and works well, but it does not need to compensate for any "droop" caused by mechanical issues. The keyboard that I am using is fairly small, and there is a ridgid metal bar installed underneath it that ensures that wherever the keyboard is pressed the sensors will activate correctly. This metal bar is visible in the posted pictures. This arrangement has been tested and works just fine.
If you plan on putting a FSR sensor directly underneath your appendage softpot ribbon then you should probably use the FSR 408 ribbon which is a long, narrow ribbon that can be trimmed to the same length as the softpot ribbon. If you have already built your appendage and the ribbon is currently attached to a ridgid surface that you want to place the FSRs underneath, then I would experiment with FSR placement to get good results wherever the ribbon is pressed. Probably three or four FSR 402s spaced evenly along the base of your ribbon mount would be fine, depending on how stiff it is. All of the FSRs can then be wired in parallel and connected to the posted circuit. Alternatively, the FSR 408 ribbon could be used here as well, but how well it works will depend on your particular physical arrangement.
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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tojpeters
Joined: Feb 04, 2013 Posts: 22 Location: cali (far north)
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Posted: Sun Feb 24, 2013 8:44 am Post subject:
very striking design |
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did you know what you were going to do with those plastic cases as soon as you saw them or did they sit around gathering dust a long time before inspiration hit you? Do you mind if i borrow heavily from your frs circuit? I want to basically build 2 of the ones that have cv and gate and add a selector for gate buss 1 or 2 to both of them along with a manual gate button that also can be routed to either or both busses. I'm thinking of adding 2 op amp mixers to combine the signals and send them to the 2 LM311. Once again very nice work. |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Sun Feb 24, 2013 11:26 am Post subject:
Re: very striking design |
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tojpeters wrote: | did you know what you were going to do with those plastic cases as soon as you saw them or did they sit around gathering dust a long time before inspiration hit you? Do you mind if i borrow heavily from your frs circuit? I want to basically build 2 of the ones that have cv and gate and add a selector for gate buss 1 or 2 to both of them along with a manual gate button that also can be routed to either or both busses. I'm thinking of adding 2 op amp mixers to combine the signals and send them to the 2 LM311. Once again very nice work. |
The cases had sat around for years before I found this use for them. I had no idea at all what I was going to do with them when I first started collecting them.
Please feel free to use the FSR circuit however you would like, that is the reason why I posted it. Thank you for the nice comments!
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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tojpeters
Joined: Feb 04, 2013 Posts: 22 Location: cali (far north)
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Mon Feb 25, 2013 12:07 pm Post subject:
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tojpeters wrote: | Do you think this would work to select gate busses, or am I overcomplicating things ? I hope you can see where this inserts into your circuit. Should I leave out the extra op amp and just connect the switches to the LM311s? Thanks for any input you have. |
In general it looks like your circuit should work, however there are a few errors in it that would have to be corrected. The diodes coming from the FSRs are connected to the positive op amp input instead of the negative, the LM311 positive and negative inputs have been reversed, and the op amps connected just before the LM311s are wired as comparators themselves, they should have a 100K feedback resistor from output to negative input to act as invertors as intended. You can simplify the circuit a bit by omitting the final op amp stages entirely and wiring the LM311 inputs backwards (as they are actually shown here.)
As well, with your manual gates wired the way that you show them, their operation will depend on the gate level setting, which you may not want. You may want to consider doing all of your gate bus mixing after the LM311s instead of before, depending on how you want the circuit to function.
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Mon Feb 25, 2013 12:11 pm Post subject:
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Oh, and the bottom connection from the far left manual trigger should be connected to the input of the next op amp stage, not to the output of the FSR op amp.
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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tojpeters
Joined: Feb 04, 2013 Posts: 22 Location: cali (far north)
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Posted: Mon Feb 25, 2013 2:17 pm Post subject:
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Thanks for looking, and correcting the numerous faults. Just to be clear this is what i hope to achieve. I assign FSR1 and FSR2 to gate buss 1. I press FSR1 and adjust gate level to 10V. Now I can press FSR1,FSR2, and manual gate 1 all at the same time,or any one of them alone and get a 10V gate signal. I think I'll redraw it with a TL072 and wiring the inputs to the LM311 "backwards". |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Mon Feb 25, 2013 2:27 pm Post subject:
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tojpeters wrote: | Thanks for looking, and correcting the numerous faults. Just to be clear this is what i hope to achieve. I assign FSR1 and FSR2 to gate buss 1. I press FSR1 and adjust gate level to 10V. Now I can press FSR1,FSR2, and manual gate 1 all at the same time,or any one of them alone and get a 10V gate signal. I think I'll redraw it with a TL072 and wiring the inputs to the LM311 "backwards". |
You may be misunderstanding what the "gate level" control does. It sets how hard that you have to press on the FSR before a gate is generated. It does not set the actual voltage of the gate output, which remains a bit above 10 volts any time that an actual gate is generated.
Other than that, it should work as you say above.
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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tojpeters
Joined: Feb 04, 2013 Posts: 22 Location: cali (far north)
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Tue Feb 26, 2013 9:15 am Post subject:
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tojpeters wrote: | I did misunderstand the gate level. Here are the {hopefully} corrected schematics if you could give them a look please. |
Everything looks OK except that you still need to correct the top manual gate connection to the bottom circuit. The 100K resistor should connect directly to pin 6 of the TL072 instead of to the output of the FSR op amp.
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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tojpeters
Joined: Feb 04, 2013 Posts: 22 Location: cali (far north)
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Posted: Tue Feb 26, 2013 11:34 am Post subject:
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Thanks. i'm really excited about this circuit. I'll be ordering the bits I need soon. |
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tojpeters
Joined: Feb 04, 2013 Posts: 22 Location: cali (far north)
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Posted: Wed May 15, 2013 8:56 pm Post subject:
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Really looking good. And sounding good,I watched the youtube video |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Sun Feb 09, 2014 12:11 pm Post subject:
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After a year and a half, this project has finally been completed!
http://www.electronicpeasant.com/projects/synthbend/synthbend.html
Take care,
Doug
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_________________ The Electronic Peasant
www.electronicpeasant.com |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
Audio files: 277
G2 patch files: 320
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Posted: Sun Feb 09, 2014 12:35 pm Post subject:
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Great build Doug, and those synths look amazing too! _________________ Jan
also .. could someone please turn down the thermostat a bit.
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sneakthief
Joined: Jul 24, 2006 Posts: 569 Location: Berlin
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Posted: Sun Feb 09, 2014 12:39 pm Post subject:
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That's an inspired project! I like how it interfaces with the rest of the modules.
ps. greetings from Berlin from a fellow Albertan _________________ Sneak-Thief - raw electrofunk |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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Posted: Mon Feb 10, 2014 10:53 am Post subject:
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Thank you for the nice comments!
This controller is really a lot of fun. I hope to do a video of the whole thing in use soon, I will definitely post it here.
Greetings to you too Sneakthief! Was -31C this morning, you are probably not missing that!
Take care,
Doug _________________ The Electronic Peasant
www.electronicpeasant.com |
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inlifeindeath
Joined: Apr 02, 2010 Posts: 316 Location: Albuquerque, NM
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BobTheDog
Joined: Feb 28, 2005 Posts: 4044 Location: England
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G2 patch files: 15
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Posted: Mon Feb 24, 2014 2:20 pm Post subject:
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Very impressive stuff, nice job! |
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tojpeters
Joined: Feb 04, 2013 Posts: 22 Location: cali (far north)
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Posted: Thu Feb 27, 2014 2:38 pm Post subject:
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Really nice. I did use one of your FSR schematics as drawn on my Martenot controller. Works great! |
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