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Subject: Re: [motm] VCDO?

From: alt-mode <alt_mode@...>
Date: 2000-07-17

Paul,

Sounds very interesting. I would like to such an oscillator with something better
than EPROM for waveform storage. Something stable that survives power loss, perhaps
FLASH? Maybe EEPROM would be better but I'd like an easier way to change around the
waveforms than to yank a chip and put it in a programmer... Of course, depending on
the size of the memory and the quality and number of waveforms in it, I might not
want to reprogram it ;)

Regarding the controls, you know the drill, the more VC control the better!

Eric

--- Paul Schreiber <synth1@...> wrote:
> It just occured to me (well, actually yesterday talking with MOTM user in
> UK) that the 4,000
> CEM3340s I have sitting here collecting dust could be quickly converted to a
> newer version of
> the Digisound VCDO.
>
> This uses the CEM3340 VCO chip in "ultrasonic" mode (ie say 1Khz to 100Khz
> range) to scan
> out waveforms in an EPROM. It's pretty easy to have VC'd waveform selection,
> etc etc a la the
> Wiard 'Waveform City' (which uses a technique prone to jitter errors).
>
> Also cute is Windoze applett to 'draw' waveforms and then create Intel hex
> file to blow into EPROM
> if you have access to a programmer (like the $129 Needhams one).
>
> Anyway, just a thought. Comments?
>
> We could get Old Crow to add a PIC to do VC'd morphing (just an ADD then a
> SHIFT before DAC).
> Or digital GAIN control (0 to +5 goes into ADC on the PIC, with a MULT to
> gain scale. If you don't
> plug a signal in, there is a 100K pullup to +5 rail into ADC to get
> full-scale output).
>
> Paul S.
>
>
>
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