[sdiy] 566 Functional Replacement

[Vladimir Pantelic]

but then 8 pins is enough for a whole "synth" ;)

http://www.synthtopia.com/content/2014/04/23/the-dsp-g1-synthesizer-a-tribute-to-the-synths-of-the-70s-80s/

On Mar 18, 2018 15:49, "Tom Wiltshire" <tom at electricdruid.net> wrote:

> This is the 3340 again. It’s 16-pin not 14-pin, but its basically what
> you’ve just described.
>
> If you want a 8-pin VCO, perhaps a little PIC thing would work? You’d only
> get 0-5V output, and 0-5V CV input, but you could have whatever waveforms
> you wanted. Something like this, but for audio rates? -
>
> https://electricdruid.net/datasheets/STOMPLFODatasheet.pdf
>
> Tom
>
> > On 18 Mar 2018, at 08:26, rsdio at audiobanshee.com wrote:
> >
> > I say let go of the 8-pin restriction. Put all three waveforms on a
> 14-pin chip and you might not need any op-amps. No need for two variations
> of the same chip just to trade one waveform for another. Sure, 8-pin isn't
> "tiny" but a full-featured OSC that's the size of a quad op-amp would still
> be quite small.
> >
> > You might still need an external capacitor or two for the various wave
> shaping, so they could use some of the extra pins. Actually, you could add
> Sync, PWM or other shape modulation, Sawtooth, and perhaps Sinusoid. The
> latter might be difficult without more support, unless you don't care about
> purity. That all fits in 14 pins, it seems.
> >
> > Brian
> >
> >
> > On Mar 17, 2018, at 11:59 PM, Tim Parkhurst <tim.parkhurst at gmail.com>
> wrote:
> >> The only problem with removing the square wave output is that an
> external tri to saw shaper needs the square to flip precisely at the peaks
> of the triangle. This happens naturally in the internal comparator of a
> typical tri core oscillator, whereas it's tricky to get precisely right
> with an external comparator (if the tri amplitude changes even a little, it
> can throw the phase relationship off). There's other waveshaping tricks
> like tri suboctaves that you can make if you've got both the tri and square
> waves from the internal circuitry.
> >>
> >> Tim (Hip to be square wave) Servo
> >>
> >> On Sat, Mar 17, 2018 at 11:23 PM, Pete Hartman <pete.hartman at gmail.com>
> wrote:
> >>> I'd ditch the square wave and use wave shaping for everything beyond
> the triangle....
> >>>
> >>> On Sun, Mar 18, 2018 at 1:19 AM, Tim Parkhurst <
> tim.parkhurst at gmail.com> wrote:
> >>> Not sure if you'd need a GND pin for reference. Op amps don't, but
> then again, they're not charging and discharging caps. Okay, so if we need
> a ground pin, I'd say to ditch the Linear CV input.
> >>>
> >>> Tim (or we could make it a 9 pin chip) Servo
> >>>
> >>> On Sat, Mar 17, 2018 at 10:32 PM, Pete Hartman <pete.hartman at gmail.com>
> wrote:
> >>>> Wouldn't you need a ground pin for reference?
> >>>>
> >>>> On Sat, Mar 17, 2018 at 10:07 PM, Tim Parkhurst <
> tim.parkhurst at gmail.com> wrote:
> >>>>> What the world really needs is a minimalist 8-pin chip VCO (DIP and
> SOIC flavors, please). 7 or better octaves of 1v/o tracking (externally
> trimmed CV) would be a huge plus. In case any chip makers or millionaires
> are listening, I'd make the pins:
> >>>>>
> >>>>> +V (9 to 12V)
> >>>>> -V (9 to 12V)
> >>>>> Expo CV In (0 to -V so that you can use a single op amp as an
> inverting CV summer, temp compensation built into the on-chip expo)
> >>>>> Linear CV In
> >>>>> Cap pin 1
> >>>>> Cap pin 2
> >>>>> Tri out (+/-5V with +/-12V supplies)
> >>>>> Square Out (+/-5V)
> >>>>>
> >>>>> Things like Sync, PWM, Saw out, Sine out could easily be done with
> external op amps, but only if needed. Maybe make a second version with Saw
> instead of Tri.
> >>>>>
> >>>>> On Sat, Mar 17, 2018 at 1:25 PM, Tim Ressel <timr at circuitabbey.com>
> wrote:
> >>>>>> I hear ya, guess I miss having a tiny solution.
> >>>>>>
> >>>>>> --tr
> >>>>>>
> >>>>>> On 3/17/2018 12:00 PM, Dan Snazelle wrote:
> >>>>>>> Honestly now that the Cem vco  is back in production , in prices
> lower than the 566 (especially in quantity ) I would think that chip would
> be a better bet.
> >>>>>>>
> >>>>>>> You basically want an OSC on a chip that has multiple waveforms
> right ?
> >>>>>>>
> >>>>>>> On Mar 17, 2018, at 1:27 PM, Tim Ressel <timr at circuitabbey.com>
> wrote:
> >>>>>>>> A while ago I asked for circuit ideas to use my rare 566s in. The
> more I got into the suggestions the more I realized just how useful the 566
> was. And the more sad I got that its gone.
> >>>>>>>>
> >>>>>>>> I am looking for a functional replacement for what the 566 used
> to do for us. A small, low part count vco design that covers more or less
> what the 566 did. I would prefer analog over digital because some uses,
> like noise modulation, may not work so well with a digital solution.
> >>>>>>>>
> >>>>>>>> I have looked at the 4046 design but it requires some components,
> especially if you want triangle output. There was a tri-core design I saw
> somewhere online that was real tight. I think it was a 13700 based circuit.
> But I can't find it now. The is the KA331 but it is DIP only.
> >>>>>>>>
> >>>>>>>> Hmm .. maybe I am out of luck.
> >>>>>>>>
> >
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