[sdiy] Newbie alert :-)

[Scott Gravenhorst]

Look here:

http://www.uni-bonn.de/~uzs159/vco4069.html

I assume you want expo control voltage input.


Nicolai Czempin <nicolai.czempin at alcatel.de> wrote:
>Hi,
>
>I'm new here, a brief introduction (plus not-so-brief general babbling, 
>and finally the actual on-topic post :-):
>
>I'm Nicolai Czempin, a 34-year old software developer from Berlin, Germany.
>Ever since I got my VIC-20 back in 1982, I have stayed firmly on the 
>software side of things.
>I have always found I was missing out on the interesting "low-level 
>stuff" called "electronics" ;-).
>
>Two facts have "pushed me over the edge" of getting started:
>a) I now work for Alcatel, albeit in a software-oriented role, but being 
>surrounded by lots of EEs.
>b) My two sons, 7 and 4.5, are developing interests in 
>technical/scientific stuff (of course I am not totally innocent in 
>that), they both want to become "robot builders" when they grow up :-), 
>and I am supplying them with [all the stuff I never had as a kid :-] 
>some basic kits (KOSMOS here in Germany). Going through the electronics 
>"starter" kit (I won't let them experiment all by themselves yet, so I 
>have to do it with them for now) did it for me.
>
>I had bought the odd book or so, and I have a modest background from my 
>Physics A-Levels (although back then I was only interested in the 
>digital stuff).
>But now I'm actually starting for real: I have bought a supply of basic 
>components and tools, have wired up a few simple circuits on a breadboard.
>Yesterday I bought an oscilloscope (without the probes, duh!) and the 
>next purchase will be a 3-output power supply.
>
>In my experience, I always need some kind of project, some goal to work 
>towards. For example, I feel strongly that a programmer should always 
>learn additional languages, not necessarily because he can use them all 
>in projects, but seeing different approaches will increase the programs 
>I write even in "standard" languages such as C++ or Java. But all my 
>attempts to learn new (to me) languages have been unsuccessful when all 
>I did was get a book and just dabble. But here in my current project 
>(I'm a contractor) my first task was to write some code in a language 
>called Ruby (that I had wanted to take a look at all along) that I had 
>never used. And lo and behold, because I had a concrete project, I was 
>able to learn the fundamentals quite quickly.
>
>So, in my aim to learn more about hardware, I have decided two areas 
>that would motivate me would be
>a) robots and
>b) music.
>
>So, to cut things a bit short, b) is why I'm here, I want to build my 
>own analogue synthesizer. I have surfed around a bit for the past few 
>days/weeks, and naturally this mailing list is where I landed.
>I am sure the question that will follow right at the end is answered 
>somewhere in the ML archives, and I apologize for not yet having 
>searched through them. I have also found the odd "how to get started" 
>page on the web. But hopefully I am adding another twist to the 
>question, but then again, maybe not.
>
>My philosophy in software development is that it should be done 
>"incrementally and iteratively". My mantra is to implement "the simplest 
>thing that could possibly work" first and then improve on it. So, from 
>my "research" (e. g. "Sound Synthesis and Sampling" by Martin Russ), I 
>have found that a "canonical" setup (apparently "hard-wired" into a lot 
>of the non-modular synthesisers) would be LFO->2VCO->VCF->VCA (naturally 
>it's a bit more compicated than what I can show in a line of text, see 
>the book for more detail). And the "simplest thing that could possibly 
>work" is one VCO.
>
>So I have collected tons of schematics for VCOs (from "300 oscillators", 
>a German book called "Experimente mit 
>Operationsverstaerkern"-experiments with opamps, plus "The Art of 
>Electronics", plus a book based on the simulation software "Electronics 
>Workbench"). So far, the only one that actually produced any sound on 
>the loudspeaker was an "astable multivibrator" based on the 555. I know, 
>it's not voltage-controlled, but having *any* oscillator oscillating is 
>a success for a rank beginner like myself. Even if the actual sound was 
>nasty :-)
>I have tried circuits based on discrete components, the 741, as well as 
>on the LM331. In many cases, I couldn't get precisely those components 
>specified by the schematics. With my semi-non-knowledge (purely 
>theoretical) I tried to substitute "equivalent" components. So far 
>without luck.
>Now, you may say, with all those EEs around me, it should be trivial to 
>get some help. Yes indeed, and I will use as much as I can. But 
>obviously this ML is the right place for synthesizer-specific questions 
>(add that most of the EEs don't actually do any hardware work :-).
>
>So, here it comes:
>Can you please give me/point me towards schematics for a minimalistic 
>VCO, that, and here's the catch, I can build with just the basic 
>components I get from "Conrad" (which, as far as I understand, would be 
>the German equivalent for "Radio Shack"). I'm not concerned at all with 
>quality, I just want something that makes some noise (actually, signal 
>would be preferred :-) on the little LS. It may be a certain lack of 
>understanding, perhaps you're not supposed to hear anything directly 
>from the VCO, and you definitely need some kind of amplifier (once I get 
>my osci probes I can at least see if "I am" oscillating anything at all, 
>that I'd just need to amplify). I wouldn't mind starting with an 
>IC-based one (because it will be simpler to build), but at some point 
>I'd like to advance to discrete components, simply because I want to 
>know what's going on under the hood.
>
>Perhaps some of you would say that I should start with something 
>simpler, but the method of trial and error has been very successful for 
>me. First, I used to just copy BASIC programs (and a lot of those were 
>way above my understanding at the time) from magazines (back in the 
>80s), and when they wouldn't work I had to spend some time trying to 
>find out why. Worked for me.
>
>Anyway. Please help. TIA. YMMV. SCNR. LOL.
>
>
>mfg Nicolai Czempin
>
>P. S. I managed to blow an analog multimeter on the day I had bought it. 
>Luckily it was of the 5 Euro variety. I guess one has to go through 
>these experiences oneself :-)
>

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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