Is this a usable master oscillator for diy synth ?

[Synthed Mind]

Hello,

I would like to know if this circuit is stable enough to use as a aster oscillator ?
The power supply will be stabilized.
It uses CMOS technology.
Greetings

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[bubzy]

welcome to electro-music !
im not entirely sure what you mean by "master oscillator"
the circuit seems to be uncontrollable(you cannot control it, not that its chaotic), there are no inputs or variables so generally, at a glance, i would say no. BUT im a total noob and there are people here who are much better equipped to help you.

(having checked for this schematic i came up with an article from intstructables in which the guy states "For example I needed to build a bi-tonal tone, modulating an approximated 1kHz frequency with a 2,5 Hz frequency."

this would suggest that the circuit as it is is unsuitable, perhaps if you changed the resistors for potentiometers, you could get some better results. if you are looking for voltage controlled oscillators, you will be needing to use more components and a slightly more complicated build than the schematic you have posted here

you may want to check out http://electro-music.com/forum/topic-34550.html for some easy to build circuits that perform well.

-bubzy

[JovianPyx]

As shown, it's a fixed frequency oscillator, as Bubzy points out. I believe that you can control the frequency by changing R1, like with a pot or a Vactrol or a bank of resisors and switches (crude keyboard) or a resistive strip and stylus. It's output waveform should be sort of sawtoothy with a curved instead of a straight ramp. Note that if you replace R1 with a pot - you really want to have a resistor in series with the pot. The series resistor will set the maximum frequency. If you use only a pot and crank it down to zero ohms, it will oscillate so high in frequency that you may not hear it. If you use a vactrol type device, the response will not be the least bit linear.

It depends on exactly what you want to do with an oscillator. If you want recognizable pitches to come out, this is probably not the best solution (even with a Vactrol). If you want to experiment with an oscillator that uses a pot to control it's pitch and you already have the parts - breadboarded and replace R1 with a pot and series resistor and see (hear) what happens. The values of the resistors and cap (or calculations for them) would be in the document where you found the drawing.

[Synthed Mind]

Hi all,
Thx for the reply !
I forgot to mention that this circuit would be calculated for only 1 frequency.
The whole idea was to use 12 of these and then to divide to lower octaves.
What I would like to know if this circuit is stable enough so that frequencies will not drift during use.
Greetings

[JovianPyx]

I don't see any components that are temperature variant enough to cause pitch drift over normal temperature range. Oscillator pitch drift you may have heard about in modular synths comes from the exponential current converter circuit which is a known temperature variant use of a transistor. There is no such circuit element in the oscillator shown. My opinion - it should work fine for your described use.

[ian-s]

You might like to look at a different design unless you don't plan to implement vibrato and/or pitch bend. Maybe you could do vibrato with a bbd on the final output.

[Tony Deff]

[richardc64]