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This is my first experiment in my modular synthesizer project. It's a voltage-controlled
oscillator by Music From Outer Space. It's designed by Ray Wilson and it's based loosely
on the old vintage Moog oscillators. Let's try it out. Here's the sine wave output. It
sounds fantastic in the lower frequencies, very similar to an old MiniMoog. We can also
try the triangle wave output which has some more harmonic information. This one gives
an especially nice sound, especially at lower frequencies. There's also a ramp wave output.
And this is actually a ramp-core oscillator, so this is the core oscillation signal. Everything
else is built on top of this via wave-shaping circuitry. Additionally, there's a pulse wave
or square wave output that has adjustable pulse-width modulation. I did make a couple
mistakes when initially putting this together. One mistake I made was that despite reading
the instructions several times over, I forgot to put this little temperature compensation
resistor in between the two matched NPN transistors. It still works because the tempco resistor
is connected electrically to the same spot it would be if I had put it in the right place,
but it doesn't get the proper temperature compensation when the board heats up. But
for my purposes as just an experimenter, it works fine. Another mistake that I made is
I put one of these transistors in backwards. Another mistake I made when sourcing components
was I accidentally ordered some of these gigantic two-kilovolt-rated point-one microfarad capacitors.
And they probably would have worked; they have the right capacitance value, if I could
even fit them on this board somehow. The lesson I learned there was to pay attention when
you're ordering a huge list of components. Using my cheap multimeter in frequency-counter
mode, I can actually check the range of this oscillator. It gets down to about one point
eight hertz. And if I go through the full frequency range, I can get it up to....just
over thirteen kilohertz. And that seems a little bit low. It should be able to get up
into the low twenties. About 20 kilohertz is the maximum frequency that humans can hear.
So I'm not sure if that's due to another mistake that I made or maybe the result of some of
the cheap components I acquired. These potentiometers have pretty low tolerance, for example. So
I'll have to investigate that further and see if I can find out what the cause is. Of
course, this is a voltage-controlled oscillator. But I don't have anything like an LFO or a
sequencer yet to modulate the frequency of the oscillator. But you can get a sense for
how it works by connecting something to one of the control voltage inputs and using the
background radiation of the universe to get some interesting frequency modulation effects.
So, over all I'm really pleased with how this project turned out. It wasn't that difficult
to put together. If you can follow directions and you know how to solder, you can assemble
this board pretty simply. And it's probably the most complicated circuit that you'll find
in a modular synthesizer project. So I've already ordered a couple more of these boards
in addition to some higher-quality components in order to build the heart of my synthesizer
project which will be a dual-VCO module with a custom front panel that I designed. In addition,
I still have to build some LFOs, VCFs, VCAs, and a sequencer which will be my own custom
design. So, stay tuned. More videos to come.