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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Mon Dec 19, 2016 4:40 pm Post subject:
emSynth Subject description: open source and 3D printed |
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Hi all,
*edit* Changed title to better name for this synth: emSynth, a name that I reserved long ago for the synth (not the url).
I received a Christmas gift from CFish (we exchanged items yay \o/) and it turns out to be sort of a minimalist's starter-synth! I am very excited about it and plan to make a modular synth beginning with this module and a power supply.
This will be my first modular synth. So I plan to create something really wild, something fun and interesting and unusual and joyful. A synth that will warm the hearts of elders and newbies alike, a synth that we can all enjoy regardless of our level of experience.
Here in this thread I will imagineer some ideas for the potential structure of the synth and hopefully some of our more experienced synth designers and builders as well as folks of any experience can chime in as we go skipping along from start to finish!
Les _________________ "Let's make noise for peace." - Kijjaz Last edited by Inventor on Mon Dec 26, 2016 3:51 am; edited 8 times in total |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Mon Dec 19, 2016 5:29 pm Post subject:
Physical Structure |
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First, the physical structure: it's a cylinder!
Second, the manufacturing: it's 3D printed!
Third, the interconnection method: it's mechanical with no soldering!
Fourth, the jumpers: to be determined!
Dozens of ideas are running through my head, trying to lasso the best ones!
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Tue Dec 20, 2016 1:04 am Post subject:
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For reasons of safety, I am opting not to DIY the slip ring, which will act as a 360 degree power and signal connection between the synth itself and the base connected to the outside world. Using a slip ring enables full rotation of the synth to any angle and any number of rotations. The slip ring shown here has 12 contacts certified for 240V and 2A, so this thing more than does the job!
Slip Ring, 12 connections
$19.95
https://www.adafruit.com/products/1196
12 conductors allows the following pin assignments:
Power Ground
Vcc +15V
Vdd -15V
Signal Ground
Mic in
Stereo out Left
Stereo out Right
USB Ground
USB +5V
USB Data+
USB Data-
USB Unknown Pin
And all of the connections are used.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Tue Dec 20, 2016 7:24 am Post subject:
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A word about grounding: star! i'll be using a star ground configuration because it is the best way (to my knowledge) to avoid ground loops. It's called a star because there is one single point which is the center of the star and all the other grounds connect to that point like the points of a star.
In this case I feel that the best place to locate the star is above the turntable.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Posted: Thu Dec 22, 2016 2:46 pm Post subject:
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I love the concept Les.
Looking forward to seeing your take on it materialize. |
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Posted: Fri Dec 23, 2016 9:42 am Post subject:
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Then I added an extra 2n 3904 amplifier, so you can hear it on a small speaker.
I love trimmers to bias transistors. Sweep it till it works good. Saves a lot of time.
Edit ( I just realized I made a mistake drawing the schematic) the top 2 PNP transistors reference 1/2 v not ground. Last edited by Cfish on Fri Dec 23, 2016 8:36 pm; edited 1 time in total |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 12:03 pm Post subject:
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Great work CFish! I see you are no cat fish at all, lol! in fact you are a circuit fish! It would make a nice credit-card synth module.
This brings to mind a project that I designed but never constructed - the credit card Karpov Strong circuit. In fact, if the emphasis is on super simple circuits that run on 9V batteries then the whole synth could be composed of credit card sized boards! Wouldn't that be cool? Let me find the link for the credit card KS board...
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 12:08 pm Post subject:
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here it is:
http://electro-music.com/forum/topic-41976-25.html&postdays=0&postorder=asc&highlight=credit+card
It has both a boolean sequencer of minimal complexity and a Karplus Strong of minimal complexity. maybe we could separate those, make each a card, and make those be two of the designs.
CFish, your work is making this project take shape in a very imaginative way - thanks!
Les _________________ "Let's make noise for peace." - Kijjaz |
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 1:00 pm Post subject:
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CFish, I like your idea of transistors only. I kinda had that thought when inspired by your transistor-only VCO and the credit card synth pushed me in another direction.
Personally I'm in a situation where I cannot really solder. I mean, I can technically but there are oxygen tanks nearby which do not ignite from the soldering but there is the danger of igniting paper which could then ignite the oxygen. So I don't solder at this point in time.
There is, however, the modern invention of the "Cold" soldering iron. The Weller unit is only $30 and I have budget for it. It does not solder any lower temp, actually it just gives you enough heat for one solder joint and then it shuts itself off. Even if you keep the button pressed it shuts off and stays off. so it all but infinitely eliminates the possibility of igniting paper with it, so it is very safe compared to ordinary soldering irons.
If I get a cold soldering iron then i can solder again.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 1:10 pm Post subject:
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CFish, Also I have wanted for a long time to make music circuits by designing 3D printable "forms" around which one could wrap the leads of discrete components and then either twist, solder, or both to make the connections. We have prior art on this site in the Lunetta sub-forum. I'll try to find it. This would be different from the prior art but similar in concept.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Posted: Fri Dec 23, 2016 1:14 pm Post subject:
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Hi Les
I believe Radio Shack sells a conductive glue to do electronics without heat.
As long as it does not give off fumes that might cause problems.
I know I have seen it somewhere, but I have never tried it. |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 1:26 pm Post subject:
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Cfish wrote: | Hi Les
I believe Radio Shack sells a conductive glue to do electronics without heat.
As long as it does not give off fumes that might cause problems.
I know I have seen it somewhere, but I have never tried it. |
Hi CFish,
I have a conductive ink pen that a friend sent me, plus I have conductive 3D printer filament. I can work with that and/or just wrap and/or twist the leads around forms. I'm going to work with your oscillator (since you sent me the parts). I'll get a cold soldering iron next month probably. Anyway, for beginners having some way to build circuits without a soldering iron is primo!
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 1:31 pm Post subject:
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Just looked up the credit card size:
84 mm x 54 mm with 3.18mm radius corner rounds
Posting here for reference.
Les _________________ "Let's make noise for peace." - Kijjaz |
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Posted: Fri Dec 23, 2016 1:47 pm Post subject:
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Forms would have been a big time saver when I made those. |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 2:32 pm Post subject:
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Cfish wrote: | Forms would have been a big time saver when I made those. |
Dang CFish, you've been around the block a few times! Takes experience to create a wonder like that...
Les _________________ "Let's make noise for peace." - Kijjaz |
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 3:54 pm Post subject:
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The Karplus Strong module could be implemented in transistor-only plus also simple and easy to build form. The key to that would be a discrete delay line so that the bucket brigade chip could be replaced. If we fix the delay to a single value, perhaps with taps and/or a replaceable gizmo, then the circuit will only need one transistor gain buffer to work.
A lot of very cool sounds could then be produced. The key question then is: how the heck do you replace a delay line with one discrete part? The answer is: a distributed RC circuit. I learned in grad school that an RCRCRCRC etc. model is a good approximation to a delay line and it's used in computer modeling of metal interconnect in processor chips. Spice models and their kin. Also I recently learned that depositing a trace made of conductive 3D printer filament can produce a distributed RC delay (or so I believe by observation).
The way that works is when you print with the filament, it naturally oozes into a layered structure. This layered structure varies in resistivity, so that several layers makes a sandwich of low and high resistivity. Also if that does not work there are two types of filament and one is 30 times more conductive than the other, so a sandwich is certainly possible.
It would be efficient and worth the trouble of swapping filament (which takes time and effort) if small modules or perhaps direct deposits on the PCB could be made in batch form.
Well, a lot of thinking out loud here. I can't try it until tonight or later because of issues with rest and recuperation and such. Long story. Save it for later, or better yet never, TMI lol!
Les _________________ "Let's make noise for peace." - Kijjaz |
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Posted: Fri Dec 23, 2016 4:46 pm Post subject:
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Les. I like the delay line idea, and the form looks great.
I worked today on layout for front panels, and went ahead and did up a VCO module.
Will try to Finish up the front panel for it tomorrow.
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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Fri Dec 23, 2016 6:57 pm Post subject:
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In 2007 my birthday present was electro-music.com;
in 2016 my Christmas present was the credit card synth.
Thanks CFish.
Les _________________ "Let's make noise for peace." - Kijjaz |
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