Funktionality of analog synthersizers - a few questions

  • Hello EE-Community,


    i plan doing a presentation on analog sound synthesis for physics class (grade 13 in Germany ;D ).
    A few years ago i started to experiment with synthesizers which led to buying a Bass Station Synth....had to sell it last year unfortunately...


    In physics classed we discussed the topic of RLC-circuits for quite a while, but i still have some questions concerning the functionality of a VCO-unit. I hope someone can help me out.
    Thanks in advance!


    Are those RLC-units actually used in common synthesizers? A book i read makes me doubt that, but i couldn't figure it out.....the following images will explain....

    We discussed this RLC-circuit which is an Armstrong/Meissner-Oscillator an can be used to create a sine tone with variable frequency altering inductance or capacitance.

    In the VCO-Chapter of a book about analog synthesizers the oscillator unit is described not as an RLC-circuit but as shown on the picture above.
    a capacitor is charged until its voltage is just a high as a certain reference voltage. The capacitor then gets short-circuited and the charging begins anew.
    This process creates obviously a sawtooth-waveform


    The thing that confuses me, is that the author describes how the above created circuit is used in most modern synthesizers. According to him even synthesizers with a sine-oscillator just modulate and bend a triangle or sawtooth waveform into a sine.
    Why don't they use an RLC-circuit? Is it unstable for musical use?


    greetings from Germany

  • I've never built an oscillator like the one in the diagram (but then I have only ever built a few oscillators). I've never used an inductor coil in any of the synthesizer circuits I built, but that's not to say it can't be done. I'd personally recommend signing up with http://www.electro-music.com and asking in the DIY forums (scroll past the sub-forums). There are some really helpful guys there with a wealth of knowledge.

  • LektroiD, thanks for the advise to the forum.
    when you built an oscillator, which type was it?


    Quote from drschmidt;32756

    Hast du Physik als Leistungskurs?


    So ähnlich, heute nennt mans Kernfach (etwas entschärft ;D ) aber das ändert sich alle paar Jahre sowieso.
    Hast du ne Idee, wie gebräuchlich Schwingkreise in "normalen" Analogsynthies sind?


    [sorry to the others for writing in German]

  • Hello
    I found your thread by google search for Meissner Oscillator.
    There was an image there that you have posted here.
    So I was going to suggest this because you would have an easy time of it and maybe some fun too.
    http://www.sentex.ca/~mec1995/gadgets/gadgets.htm
    There are always great little tutorials all over the www.
    The one place that I could find the 555 with a transistor in the timing control is
    http://www.sentex.ca/~mec1995/gadgets/555/555.html
    look down at circuit 10, Better Timing.
    Oh! Have you tried blocking oscillators?
    How about a Bedini motor or the SSG?
    Very similar circuitry.
    I like to use the 555 though because I knew about it before all this other new hype.
    P.S. What do you think of a Hartley oscillator?
    Have you ever built a radio receiver/transmitter?

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