[sdiy] 566 Functional Replacement

Tom Wiltshire tom at electricdruid.net
Sun Mar 18 20:00:00 CET 2018


That’s a pity. Perhaps he was trying to squeeze too much in and didn’t leave space enough to get everything working nicely. But some of that just sounds buggy - odd drop-outs and glitches.

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 18 Mar 2018, at 18:31, Roman <modular at go2.pl> wrote:
> 
> And it sounds like crap and makes unpredictible things.
> I don't know maybe I got some older version. It was about 3 years ago.
> Hear for yourselves. All the quirks you hear are not recording malfuncions, it's 100% how it was.
> 
> https://soundcloud.com/roman-sowa/sdp-g1-tryout
> 
> Roman
> Dnia 18 marca 2018 16:14 Vladimir Pantelic <vladoman at gmail.com> napisał(a):
> 
> 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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