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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Tue Feb 26, 2013 10:47 am Post subject:
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chieffrancis wrote: | For example, if I had 1/4" inputs and outputs on every module, (VCO, VCA, VCF, ADSR, Noise, etc.), I would be able to create a signal path using instrument cables in whatever order I please right? |
Yes, that's the joy of Modular
chieffrancis wrote: |
As long as the voltage controlled oscillators, voltage controlled amplifier, and some arbitrary speaker or output, I should be able to get sound coming out right?
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Yes, if you have them hooked up correctly.
chieffrancis wrote: |
Also, concerning the keyboard, I am trying not to spend over $500 total for this project (hardware), so getting a MIDI to CV converter is probably out of the question since I've only seen those that are above $100. I know control voltage is decided by which keys are pressed on a CV keyboard but how are the gates and triggers done? Are these signals generated by the keyboard and sent to the VCO, as well as other modules through the same key press that sends the CV signal? |
There are DIY MIDI->CV projects out there. I adapted an old one by Thomas Henry to use Arduino:
http://electro-music.com/forum/topic-52722.html
That doesn't have complete circuit diagrams, I could probably come up with some given enough time. But if you start from the original circuit by Thomas, and look at the Arduino pins noted in the code, you could figure it out.
I'm certain I didn't spend $100 making that. I used a mintduino kit built onto protoboard, and I believe now you can get an Arduino Leonardo for $20 or $25 that doesn't require extra hardware to get your USB connection running.
I would really expect if you want to build a significant portion of the circuits from Analog Synth for the 21st Century you will absolutely be spending more than $500. I've done more than just those circuits, but I've spent several times that over the last year, getting a parts stock, getting the necessary tools, buying pots and jacks alone costs a LOT, and it's not clear to me that when you say you have the parts "sorted" whether that includes those particular pieces. I could see getting the other components under $500, but with PCBs and panels and panel components.... not so much.
So what is your ultimate goal?
Honestly, from what you say here, it sounds to me like your best bet might be to get some MFOS kits and do them. At a minimum, if you don't want to do MIDI->CV, you could use this keyboard like controller: http://www.musicfromouterspace.com/forums.html?MAINTAB=SYNTHDIY&PROJARG=MFOSMINICONTROLLER/MFOSMINICONTROLLER.php&VPW=1644&VPH=770
The Soundlab Mini Synth and one of these would give you the basics to do a lot of sound generation, and I'm pretty sure it could be done under $500 if you don't count your time investment in the cost. |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Wed Feb 27, 2013 3:31 am Post subject:
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hmm..
I actually just got an e-mail from Mr. Scott Stites and he actually cleared everything completely up that I ever questioned. It seriously was awe-inspiring.
So my new questions are these:
Is there a place that you can send a circuit to and they turn it into a PCB?
Is there a place you could go to design rack units/interface panels?
Are there any special tips & tricks for the "home depot" side of building a synth? |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Wed Feb 27, 2013 3:32 am Post subject:
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Oh and thanks to all the posters in this thread, you really helped me a lot!
especially ^^ |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Wed Feb 27, 2013 6:21 am Post subject:
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chieffrancis wrote: | hmm..
I actually just got an e-mail from Mr. Scott Stites and he actually cleared everything completely up that I ever questioned. It seriously was awe-inspiring.
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I'm jealous
chieffrancis wrote: |
So my new questions are these:
Is there a place that you can send a circuit to and they turn it into a PCB?
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Many. One of the threads discussing this:
http://electro-music.com/forum/viewtopic.php?highlight=itead&t=54700
Edit: note that it is more complicated than just sending them a circuit diagram; you have to actually send "Gerber files" which define the circuit layout.
chieffrancis wrote: |
Is there a place you could go to design rack units/interface panels?
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The main one people use is Front Panel Express, who have a free panel designer application. It's kind of spendy, but there is a 20% off coupon for now. http://www.muffwiggler.com/forum/topic-78838.html&highlight=
I don't do that, I get bulk 1/16" aluminum plate cut to 1U, 2U and 3U sizes from http://www.metalsupermarkets.com/ and put stickers on it after I drill the holes.
chieffrancis wrote: |
Are there any special tips & tricks for the "home depot" side of building a synth? |
Only one I can think of offhand is buy roof flashing to make into brackets for your PCBs. Works great, though you'll need a pair of tin snips to cut it and be prepared to drill the holes you need....and I usually find a coarse round file helpful when I screw up the hole placement .
I suppose a similar thing is the synth case made from an Ikea RAST bookshelf: http://www.muffwiggler.com/forum/topic-65505.html&highlight=
Good luck |
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Paradigm X
Joined: Feb 15, 2011 Posts: 363 Location: Null and void
Audio files: 2
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Posted: Mon Mar 04, 2013 10:17 am Post subject:
Re: An Analog Synthesizer for the 21st Century |
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roglok wrote: |
Hey Tim,
Anyway, let me first share some pictures:
Thank you Thomas Henry! |
Looks awesome man, will listen to the samples later
I love phasers.
I was intrigued to see that the Oakley, MFOS, AS21C and the frequencycentral phasers all seem to be based on the LM13700, interested to hear the differences. I bought AS21c so might try to stripboard it, youve made it look very easy (really nice build too). I built the Oakley one, with the optional deep board which adds another 4 stages...
Cheers
Ben |
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Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
Audio files: 11
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Posted: Mon Mar 04, 2013 12:24 pm Post subject:
Re: An Analog Synthesizer for the 21st Century |
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roglok wrote: | Tim Servo wrote: | roglok wrote: | I just finished a compact stripboard layout of the VC Phase Shifter... let me know if you are interested... |
Cool. I haven't tried the phase shifter yet, but it looks interesting. Let us know what you think of it. Share a sound sample if you can.
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Hey Tim,
I got around to recording some samples of the phase shifter today. I felt a little obliged to record these, because I added the triangle portion of your 8K LFO as a piggyback PCB The only other deviation from the original are 560pF caps for the filters (instead of 470pF). Not sure if/how that affects the sound...
This is my first phaser, so I can't really compare it, but I like it. I think the resonance/feedback could be a bit stronger - maybe this can be modified... Apart from classic phasing sounds, you can get some interesting VCA-like phase cancellation out of it. Overall it is a more complex module than I expected. I guess I need some more time to play with it.
Thank you Thomas Henry! |
Nice work! That's a very clean stripboard layout. I think the depth of the resonance is about as good as one would expect from a 4-stage phaser, although you might want to play a bit with the feedback and see if a little more gain will help. Also, the 560pF caps would result in a lower overall frequency from the phaser stages. The difference would be worth looking into. It would also be interesting to hear what 8 stages of this phaser would sound like. The best phaser I've ever heard was the one on the old ARP Quadra, and that had 14 stages, so that gives you some idea of the additional 'depth' afforded by more stages. Unfortunately, the additional circuitry gives you more noise. I think the ARP phaser (and the J.H. clone) use companding circuitry to reduce the noise levels.
Anyway, great work, and thanks for sharing your samples!
Tim (set phaser to stun?) Servo |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Thu Mar 07, 2013 12:17 pm Post subject:
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elmegil wrote: | chieffrancis wrote: | hmm..
I actually just got an e-mail from Mr. Scott Stites and he actually cleared everything completely up that I ever questioned. It seriously was awe-inspiring.
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I'm jealous
chieffrancis wrote: |
So my new questions are these:
Is there a place that you can send a circuit to and they turn it into a PCB?
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Many. One of the threads discussing this:
http://electro-music.com/forum/viewtopic.php?highlight=itead&t=54700
Edit: note that it is more complicated than just sending them a circuit diagram; you have to actually send "Gerber files" which define the circuit layout.
chieffrancis wrote: |
Is there a place you could go to design rack units/interface panels?
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The main one people use is Front Panel Express, who have a free panel designer application. It's kind of spendy, but there is a 20% off coupon for now. http://www.muffwiggler.com/forum/topic-78838.html&highlight=
I don't do that, I get bulk 1/16" aluminum plate cut to 1U, 2U and 3U sizes from http://www.metalsupermarkets.com/ and put stickers on it after I drill the holes.
chieffrancis wrote: |
Are there any special tips & tricks for the "home depot" side of building a synth? |
Only one I can think of offhand is buy roof flashing to make into brackets for your PCBs. Works great, though you'll need a pair of tin snips to cut it and be prepared to drill the holes you need....and I usually find a coarse round file helpful when I screw up the hole placement .
I suppose a similar thing is the synth case made from an Ikea RAST bookshelf: http://www.muffwiggler.com/forum/topic-65505.html&highlight=
Good luck |
What are decent size dimensions for the synth rack units?
I'm thinking about having 12 units, (2 ADSRs, XRVCOs, VCFs, and LFOs, 1 VCA, Noise Source, Sample/Hold, and Phase Shifter).
What do you guys think?
I'm thinking a 2 full octave keyboard (still haven't decided between MIDI2CV or OG CV).
Thanks guys |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Thu Mar 07, 2013 1:50 pm Post subject:
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Standards for sizes:
http://www.modularsynth.com/chart.html
Most of the modules will have a standard of width, and modules are N x that width. I like MOTM where the increment is 1.75", and most of my modules are 2U wide, though a single ADSR would only have to be 1U (and I actually shoehorned a dual into 1U but sometimes regret it)
Noise, sample & hold, phaser, not so sure, those could even be combined (noise & S&H have an affinity for example), and I think at one point I intended to do noise + S&H in 1U.
I'd advise picking a standard rather than rolling your own, that way if you decided to add more commercial modules or kits you won't have to adapt much.
Power standard will be important too. Again I use MOTM 4 or 6 pin .156 headers. I started out rolling my own, and I have ended up building a lot of adapter cables, but I have enough PCBS that support the 4 pin headers that it's easiest for me to stick with. |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Thu Mar 07, 2013 2:37 pm Post subject:
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When purchasing Aluminum sheets, I'm only accounting for the panel's height and length right? Maybe an L-shape to physically attach the board to the face panel?
I assume the boards themselves won't be covered by aluminum but rather mounted similar to the Phase Shifter above.
I also want to encase it with some see-thru plastic all around the module racks to physically protect the circuits, maybe a wooden finish around the keyboard (unlikely, but I like to dream). |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Thu Mar 07, 2013 7:36 pm Post subject:
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Yep. Front panel is always in my experience separate from the mounting bracket. There are several types though. Page through the build threads and you'll see lots of examples. |
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roglok
Joined: Aug 28, 2010 Posts: 202 Location: uptown
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Posted: Tue Mar 12, 2013 7:34 am Post subject:
Re: An Analog Synthesizer for the 21st Century |
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Paradigm X wrote: |
Looks awesome man, will listen to the samples later
I love phasers.
I was intrigued to see that the Oakley, MFOS, AS21C and the frequencycentral phasers all seem to be based on the LM13700, interested to hear the differences. I bought AS21c so might try to stripboard it, youve made it look very easy (really nice build too). I built the Oakley one, with the optional deep board which adds another 4 stages...
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Thanks! I'm curious about the frequencycentral one, too... I might build one and compare... If you feel like building the 21c from my layout, send me a PM - it took quite a bit to layout and would be a shame it was just for myself. .
Tim Servo wrote: |
Nice work! That's a very clean stripboard layout. I think the depth of the resonance is about as good as one would expect from a 4-stage phaser, although you might want to play a bit with the feedback and see if a little more gain will help. Also, the 560pF caps would result in a lower overall frequency from the phaser stages. The difference would be worth looking into. It would also be interesting to hear what 8 stages of this phaser would sound like.
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Thanks Tim - that's some very valuable info. I'll try messing with the cap values. Do the individual filter stages have to be at the same frequency or would different cap valued work too? adding four more stages wouldn't be too hard, I guess - will look into that ... |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Thu Mar 14, 2013 9:44 pm Post subject:
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Does anyone have a perfboard example on using bypass caps?
Is there a need for a heatsinking/fans?
Thanks guys. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Thu Mar 14, 2013 10:15 pm Post subject:
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Not sure what you mean about perfboard example using bypass caps. You just need the caps as close as possible to power pins, going to ground. I've always been pretty lazy about where I get ground from, usually there's a ground somewhere nearby.
There should be no need for heatsinks or fans on anything but the power supply, and even that should only be heatsinks. |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Thu Mar 14, 2013 10:17 pm Post subject:
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I guess what I'm asking is, where exactly do the pins go?
And should I be bending these capacitors so that it's physically closer? |
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prgdeltablues
Joined: Sep 25, 2006 Posts: 222 Location: UK
Audio files: 12
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Posted: Fri Mar 15, 2013 5:43 am Post subject:
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Ideally you want to have the capacitor as close as possible to the power pin of the IC, with as short legs on the cap as possible. So one leg of the cap should go in a perfboard/stripboard hole right next to the V+ or V- power pin on the IC. Of course, you also need to get power to that pin... sometimes I end up with the cap a couple of holes further away - I don't think it matters for analog synth circuits. If it's a stretch between the power pin and a ground point, it's good practice to make the leg of the cap shortest on the side close to the power pin on the IC - it's not the physical closeness of the cap body that matters, but the length of wire between the cap and the IC pin (so, no, bending it won't achieve anything).
Peter |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Fri Mar 15, 2013 8:09 pm Post subject:
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prgdeltablues wrote: | Ideally you want to have the capacitor as close as possible to the power pin of the IC, with as short legs on the cap as possible. So one leg of the cap should go in a perfboard/stripboard hole right next to the V+ or V- power pin on the IC. Of course, you also need to get power to that pin... sometimes I end up with the cap a couple of holes further away - I don't think it matters for analog synth circuits. If it's a stretch between the power pin and a ground point, it's good practice to make the leg of the cap shortest on the side close to the power pin on the IC - it's not the physical closeness of the cap body that matters, but the length of wire between the cap and the IC pin (so, no, bending it won't achieve anything).
Peter |
Ah thank you. So the capacitor is supposed to make a short ac bridge between the sources and ground. That clarifies it. |
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prgdeltablues
Joined: Sep 25, 2006 Posts: 222 Location: UK
Audio files: 12
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Posted: Mon Mar 18, 2013 2:51 am Post subject:
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Yes. The cap serves as a small power reserve for the IC, helping reduce noise on the power/ground lines. |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Thu Mar 21, 2013 10:04 am Post subject:
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Hello again guys,
I scoured around the internet looking for answers to the frequently asked, seldom completely answered question of...(dun dun dun...):
What is a good replacement for the LM394 matched pair?
Thus far I've received these answers:
2SC1583 - don't remember how I got this one
SSM2210
SSM2164
MAT02 - obsolete
MAT12
THAT300 - series, specific model number not available
SSM2212 - SOIC solution
Some of these are discontinued and/or expensive/only sold in bulk of 100+.
If anyone could shed some light on this, that'd be great! I'm searching for a DIP solution (SMT will work as well, but I'm not trying to buy a bunch of SMT-DIP adaptors). Also, 8-pin would be great, but 14-16pin >2 matched pairs would work as well.
On some of the forums I read that there are replacements for the matched pairs with similar specs that come in 14 or 16-pin models.
I'd really like to make a comprehensive guide (or something similar) including replacement (up-to-date) parts on Thomas Henry's designs (or maybe even come up with my own? Not likely but we'll see).
I've seemed to have found all the parts I need from around the world (from eBay, electronic goldmine, mouser, etc.) so construction shall begin as soon as I find a good replacement for these matched pairs for the XR-VCO.
I also finally got some MIDI keyboards (that are broken) that are just asking to be turned into my CV input for my synth.
Happy Spring! |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Thu Mar 21, 2013 10:34 am Post subject:
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I'm also thinking about enclosing the modules with plexiglass or some other sort of see-thru material.
Any advice on the best kind of material (and the howabouts of getting one to sit nicely on the synth).
I don't want any weird chemical reactions, melting plastic during some good sound designing, or slurry seal that costs me a leg.
Thanks! |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Thu Mar 21, 2013 11:51 am Post subject:
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I bought 5 x LM394 from jk_parts on EBay almost exactly a year ago, and it cost me just shy of $21US. I used one of them for the el Cerrito (which is essentially the XR-VCO), and it seems like it works, however I have not tested it extensively. They are a Chinese seller and it does generally involve some risk buying from China through EBay (I bought some MN3005's for example that were bogus, but the seller did allow me to return them).
the SSM2164 is a VCA, not a matched pair, so strike that out of your list.
You probably could do fine with hand matched 2N3904's or whatever the BC NPN equivalent is. Search the forums here for transistor matching, and use the circuit described by Ian Fritz (I don't have the URL handy just this moment or I'd just include it), and you should be able to do well. Thomas' newer designs use that approach and work great. |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Fri Mar 22, 2013 7:43 pm Post subject:
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Am I allowed to post circuits of the keyboard my friend lent me to be sacrificed for this project?
I've got some questions as to what I've found and would like to know if anyone has come across this circuit and how I could transform it into a 1V/Oct input for my VCO(s) as well as pull out some trigger and gate signals. It has some built in mod wheels and buttons and is connected via USB, but also can receive DC power as the main source. |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Fri Mar 22, 2013 8:33 pm Post subject:
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Your friend "lent" it to you? Does he expect it back after being sacrificed?
I think a lot depends on what you are proposing to post.
1) is it a current/relatively new keyboard? If not, you probably don't have anything to worry about.
2) are the service manuals/schematics available online? If so, you definitely don't have anything to worry about.
3) are you going to post the entire schematic so someone could duplicate the whole keybaord? I would bet not, and if not, you probably don't have anything to worry about. |
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Sat Mar 23, 2013 5:47 am Post subject:
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I'm thinking about donating the project to his garage and adding it to our little crew's arsenal for taking the music world over by storm..or something similar.. haha so in a sense, yes, he does expect to see it again, but this time, evolved.
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chieffrancis
Joined: Feb 07, 2013 Posts: 88 Location: california, united states
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Posted: Sat Mar 23, 2013 5:50 am Post subject:
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Sat Mar 23, 2013 6:54 am Post subject:
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Ok, somehow I was thinking Schematic, not literal circuit.
Both sides of each board are important.
Some idea how they are connected is important.
What is the keyboard? I think you'll get the most bang for your buck looking for a service manual. |
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