[sdiy] 566 Functional Replacement

[Tim Parkhurst]

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.
>>>>
>>>>
>>>> Tim (All you need is cash) Servo
>>>>
>>>>
>>>>
>>>>
>>>> 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
>>>>>> ?
>>>>>>
>>>>>> Sent from my iPhone
>>>>>>
>>>>>> On Mar 17, 2018, at 1:27 PM, Tim Ressel <timr at circuitabbey.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> 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.
>>>>>>>
>>>>>>> --
>>>>>>> --Tim Ressel
>>>>>>> Circuit Abbey
>>>>>>> timr at circuitabbey.com
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Synth-diy mailing list
>>>>>>> Synth-diy at synth-diy.org
>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>>>
>>>>>>
>>>>> --
>>>>> --Tim Ressel
>>>>> Circuit Abbey
>>>>> timr at circuitabbey.com
>>>>>
>>>>> _______________________________________________
>>>>> Synth-diy mailing list
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>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>
>>>>
>>>>
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>>>>
>>>
>>
>
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