[sdiy] inexpensive chips for oscillators (still learning...)

[Kyle Stephens]

http://www.beavisaudio.com/Projects/CMOS_Synthesizers/

Knock yourself out. The chips and parts used herein are cheap and can sound pretty neat - moreover, everything's readily breadbaordable.


_Kyle

--- On Mon, 9/26/11, Bob K <farfisa5 at gmail.com> wrote:

> From: Bob K <farfisa5 at gmail.com>
> Subject: Re: [sdiy] inexpensive chips for oscillators (still learning...)
> To: "synth-diy DIY" <synth-diy at dropmix.xs4all.nl>
> Date: Monday, September 26, 2011, 12:54 PM
> Wow.  Thanks again for the more
> information.
> 
> I'm a beginner but can read schematics and am learning my
> way around a
> breadboard.
> 
> The initial project is just going to be a little noise box
> with two
> pots, one to control the frequency and the other to control
> the
> volume, and no inputs.  After I get that going I'll
> add more
> oscillators and more knobs.
> 
> So it looks like I'll start off with the CMOS 7555/TLC555
> and see what happens.
> 
> I'll take a look at the PAiA schematics and see what
> they're doing.
> 
> Again, thanks!
> 
> -Bob
> 
> On Mon, Sep 26, 2011 at 11:26 AM, Scott Gravenhorst <music.maker at gte.net>
> wrote:
> > Dave Kendall <davekendall at ntlworld.com>
> wrote:
> >>You probably know this already, but if using 555s,
> go for CMOS versions
> >>(7555, TLC555 etc) which draw *far* less power.
> It's my understanding
> >>that the regular 555 can cause problems with power
> consumption when
> >>switching.
> >
> > The datasheet I have for the 7555 has current graphs
> that show the difference between
> > the bipolar 555 and the CMOS 7555 while they are
> switching.  The difference is
> > amazingly large.
> >
> > In fact, the PAiA Fatman had been designed using
> bipolar 555 timers for the two VCOs.
> >  Unmodified, it has a notable problem of soft
> synching the VCOs when they are close
> > in pitch.  This is because even though the 555 is fed
> power through a 100 ohm
> > resistor with a 100 uF cap to -12V, there is still a
> significant current spike at
> > switching time that propogates to the other VCO.  A
> fix was designed by PAiA which
> > replaces the 100 ohm resistor with an LED.  Another
> fix that I found after learning
> > about the 7555 was to simply replace the bipolar 555
> with CMOS 7555.  The two fixes
> > work about as well as each other, but I prefer the
> 7555 fix over the LED fix.
> >
> > +1 for 7555.
> >
> > And you can go to www.paia.com and look at the
> schematic for how they turned a 555
> > (or 7555) timer into a VCO.  It is a _linear_ VCO,
> but enterprising lovers of expo
> > could probably convert the VCO's voltage to current
> converter to use expo instead of
> > linear pitch CV.
> >
> >>On Sep 26, 2011, at 17:21, Bob K wrote:
> >>
> >>> Hi everyone,
> >>>
> >>> New here.  Hi.  How's everybody?  Fine?
>  That's good.
> >>>
> >>> After skimming through the two Forrest Mimms
> books I have and "Make:
> >>> Electronics", both books are making a point
> that 555 and 556 chips are
> >>> a good (and cheap) start for breadboarding
> oscillators.
> >>>
> >>> I'm planning on a bulk purchase (bulk meaning
> around 10) of the above
> >>> mentioned chips and was wondering if there are
> any other cheap chips
> >>> along the lines of the 555 and 556 that can be
> used for oscillators?
> >>> I'm going to search online for advice as well
> but thought I'd run this
> >>> question by everybody here.
> >>>
> >>> Thanks.
> >>>
> >>> -Bob
> >>>
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> >>>
> >>
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> >
> > -- ScottG
> >
> ________________________________________________________________________
> > -- Scott Gravenhorst
> > -- FPGA MIDI Synthesizer Information:
> >   jovianpyx.dyndns.org:8080/public/FPGA_synth/
> > -- FatMan:
> >   jovianpyx.dyndns.org:8080/public/fatman/
> > -- NonFatMan:
> >   jovianpyx.dyndns.org:8080/public/electronics/
> > -- When the going gets tough, the tough use the
> command line.
> >
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