[sdiy] Newbie alert :-)

[Nicolai Czempin]

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 :-)