[sdiy] pwming a tog

Tom Wiltshire tom at electricdruid.net
Wed Sep 20 15:57:00 CEST 2017


I think the Jen works by using the dividers to build a staircase waveform as a cheap ramp replacement, and then doing PWM on that. That might be a possible approach. The PWM response is a bit “lumpy” but it’s not bad.

Tom

> On 20 Sep 2017, at 14:02, Csaba Nagy <icnagy at gmail.com> wrote:
> 
> I think the Jen SX1000 uses something like a TOG and has PWM. Although it's a mono-synth.
> 
> Csaba
> 
> On 20 September 2017 at 06:13, Michael E Caloroso <mec.forumreader at gmail.com> wrote:
> The Polymoog is a TOG based synth using Polycom card PER KEY to
> implement PWM.  Each Polycom card a custom IC that included a
> waveshaper.
> 
> MC
> 
> On 9/19/17, Mike HEQX <mike at heqx.com> wrote:
> > Yes I did look at the flat keys piece recently as well as the dsp synth
> > psuedo-tog which is $25.
> >
> > http://www.dspsynth.eu/
> >
> > This really interesting page
> >
> > http://www.armory.com/~rstevew/Public/SoundSynth/TopOctave/topdividers.html
> >
> > This article
> >
> > http://www.logosfoundation.org/kursus/2073.html
> >
> > and this
> >
> > http://www.narcisivalter.it/progetti/top-octave-synthesizer-5010.html
> >
> >
> >
> >
> > On 9/19/2017 7:49 PM, Dave Garfield wrote:
> >> Hi, all
> >> While it doesn't do PWM, an English company named FlatKeys produces a
> >> Top Octave Generator replacement for the classic synths and organs
> >> which use a 50240 TOG.  This one isn't just a divider; it generates 12
> >> separate top octave waves which are in tune, unlike the originals'
> >> approximations.
> >> It will also do vibrato, as it has a master clock. It can switch
> >> octaves if desired, or transpose keys.
> >> The price is £52.80.
> >> I haven't tried one out, but have been meaning to for a long time.  If
> >> anyone else out there has, I'd love to hear about it - warts and all.
> >> Maybe it will work for you, or someone else out there.
> >> FK50240 MK50240 <http://www.flatkeys.co.uk/MK50240.html>
> >> I am NOT affiliated with FlatKeys in any way, shape, form or manner.
> >> Just thought that this might be a good solution for replacing scarce
> >> top octave divider chips.
> >>
> >>
> >>
> >>
> >>
> >>     FK50240 MK50240
> >>
> >>
> >>
> >> <http://www.flatkeys.co.uk/MK50240.html>
> >>
> >>
> >>
> >> On Tuesday, September 19, 2017 5:32 PM, Tom Wiltshire
> >> <tom at electricdruid.net> wrote:
> >>
> >>
> >> Because the standard TOG is based on dividers, you can’t add PWM. Run
> >> any width pulse wave through a flip-flop and the output's a square,
> >> after all.
> >>
> >> That said, there were some TOGs the produced 33% pulse waves rather
> >> than squares (not sure exactly what the internals were to do that) but
> >> there were none that offered PWM.
> >>
> >> If you had twelve ramp oscillators for the top-octave, you could
> >> arrange ramp+squares to give you ramps at various divided octaves, and
> >> then use those ramps to produce PWM, but it’d be a lot of circuitry,
> >> and it’d probably get a bit sensitive. Have a search for “sub-octave
> >> ramp wave” to get the basic idea.
> >>
> >> HTH,
> >> Tom
> >>
> >> ==================
> >>       Electric Druid
> >> Synth & Stompbox DIY
> >> ==================
> >>
> >> > On 20 Sep 2017, at 00:06, Mike HEQX <mike at heqx.com
> >> <mailto:mike at heqx.com>> wrote:
> >> >
> >> > I wanted to do something with a TOG and I was hoping I could add PWM
> >> to it. Not sure if you can PWM the master clock though, but that's
> >> what I want to try. After all you pitch bend it that way.
> >> >
> >> > I not does that mean 12 pwm on the output of the tog?
> >> >
> >> >
> >> > thoughts?
> >> >
> >> >
> >> > Mike
> >> >
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> >>
> >>
> >>
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> >
> >
> 
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> 
> 
> -- 
> Csaba
> 
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