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"A Journey begins with a single step"My 1st synth
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author "A Journey begins with a single step"My 1st synth
Hello, after burning my hands for a few months with a soldering iron I have decided that I would like to try to build my own synth. After pillaging this forum and binging youtube videos I have decided that It is well within my ability to do so. The video that I have watch that made this clear to me was this . It is a long one, I am not asking you to watch it I will just be referencing it a few time throughout this mini-essay/questionnaire.
I plan on using this as a template to build a basic oscillator and set up the ability to alter the pitch with LFO’s and variable resistors (such as Potentiometers, LDR’s and possibly even a graphite drawing or a copper bar). I also will add oscillators that produce different waveforms. Any way, the only thing that gave me pause about using this as ( and other oscillator schematics) template was at the end he said this was a Current controlled oscillator and not a Voltage controlled oscillator. I have not been able to find information on how these two types of oscillators are different in the context of a synth online.
I was curious if by using A CCO and not a VCO I would be able to make free-standing Oscillators with their own pitch/ volume potentiometer that could be controlled via some sort of patch cable. Because in the video he was using a breadboard to make a “Hard connection”, I guess , between the Oscillator and LFO.

would I be able to make both of those oscillators free from each other. Then connected with with a patch cable? From my limited knowledge of the internal components of a synth, I would guess I would a 3.5 mm input and output jack in their respective places along the circuit then connect it with a patch cable. That is my main concern. Being able to patch freely.
Also, kind of a side note that is dependent on the answer to my question. In another example he use a square wave oscillator (#1)(different capacitor value then in diagram) before the oscillator that produces sound(#2) in a way that caused the pitch of OSC #2 to move up in steps instead of a slide of when he moved the potentiometer of OSC #1. If I was able to patch these type of oscillators would I be able to have a sine wave LFO connected to OSC #1 in order to automate the pitch of OSC #2?
My other concern is if these types of Oscillators (CCO) are compatible with Eurorack modules. I can make oscillators I'm sure of that. Possibly even a step sequencer or two. But I don’t think I would be able to make any type of Modulation effects outside of a High/lowpass filter. And was wondering if in the future I would be able to get Modulation module like a waveshaper , envelope generator , ring modular, and run my DIY Current controlled Oscillators thru them then into the output. Or possibly even run a DIY LFO thru a modular waveshaper then into a DIY CCO to the output. If that is not possible Then I would just go and try and find some VCO schematics to make. UNLESS! A VCO is miles more complicated to DIY with/without a kit. If that is the case I would be more then willing and kinda happy to just circuit bend guitar pedals and other types of audio processors into my DIY synth. But I feel that if VCO are the only way to go to get Eurorack compatibility and they are not that much more complicated then the CCO or other Oscillators I find on youtube or if this schematic just needs a few adjustments to become a VCO. Then I’d do that. Because if possible I’d like to have both Eurorack type modulation modules and circuit bent modulation in my synth. So, I can have a wide range of effects that I could add at a later date. And also use these modulation processors to make my piezo element instruments sound otherworldly.
Thank YOU for reading my wall of text! I appreciate all input and will be glad to clarify if need be. Also one last question what effect would a putting a variable resistor at the input of OSC #2 have? He Didn’t do that in the video or maybe I’m forgetting that part. It is late. THANK YOU again!
Good luck! Have a look at this book Handmade Electronic Music: The Art of Hardware Hacking by Nic Collins, what you are doing is effectively this type of circuit bending. Getting things working to a Euro rack standard will take a bit more work. There is a further step to go from "working with" to a resilient, compatible stand alone module- I mean one with sensible current drain, proper input and output loads etc.

Now is the time to see if you prefer patch cables, hard wired or switched connections. Experiment and see what mix of the above works for you. Looking quickly at the video (I have seen it before, it's good) you can see the patching cables there are single pole (no + and -) and this can be a simple way of patching, this is the world of the 4mm banana plug (in my opinion they way ahead!)

To answer your last question, the variable resistor will vary the effect osc1 has over osc2. Keep the 10k resistor and put the pot in after that. This is what breadboarding is for.
ashleym wrote:
Good luck!.
Thanks for the Book suggestion. I'm looking over a preview of it and it seems to be up my alley. So, from my understanding what you are saying that these types of Oscillators are patchable but are not compatible with Eurorack modules. But They could be altered to do so it would just require very precise work and understanding of the internal working of a synth. So as a first build it would be good just to build these simple oscillators and get a better idea of how I want my synth to work and how I may go about getting to do that. Is that about what you are saying? Also, could you explain or provide a resource that would explain how a VCO works Compared to the CCO made in the video I linked?
Yes! That is what I am saying. I am afraid to say describing the difference in the working of voltage and current controlled oscillators is beyond me and best left to others.

Have a look here

As you can see from the difference in complexity between the cct diagram you have put up and this one from Yuri, there is quite a lot to getting a "complete" VCO.

Have a look at the learning resources here and maybe even buy a kit to get a "normal" working module. Alternatively you can carry on making circuit bent stuff. I have used the ideas for apprentices at work and I made a unit based on the circuits and controller in the book for a musician - a proper gigging one. There was a lot of range limiting with this or else the oscillaters had too much range. Dont forget how LDRs react to stage lights........
Yea... That alot more lol. Thank You for your time! I will continue to learn And take on Vcos at a later date. Thanks again
Don’t get disheartened by the complexity of the Yusynth circuit. The oscillating core is similar to what you’re used to. It’s the extra bits in the circuit that makes it work as a VCO in a modular.

For example, most of the stuff on the right of the diagram (right of U6A, see how everything comes from one point?) is used to make the different waveshapes. The oscillator core will usually put out a triangle wave. The circuitry shapes this into square, sine etc. The circuitry on the left is for getting control voltages into the core.

The key part (for regular melodic playing) is the bit that converts linear volts per octave into the correctly scaled frequency doubling per volt. (I’m missing a lot of detail here and simplifying terms because I don’t know your knowledge level rather than assuming you know nowt).

Look at U6c. See the connections going in and out of it and you’ll realise it is the PWM part of the circuit. This block is a comparator. These are useful building blocks and something you’ll see a lot. What are they? There’s plenty on line, have a look here and then you’ll see that they’re often used to convert triangle waves into square waves WITH the ability to control the pulse width if the wave!!

BTW if I’m talking tosh anyone is free to correct me
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