MOTM

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CEM3340s I have sitting here collecting dust could be quickly converted to a
newer version of
the Digisound VCDO.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.

Here's my 2 cents....

I like the VCDO idea. But I'd rather not be slaved to a write once (for all practical purposes) wave library. How about, instead of EPROM, something like a MIDI sysex wave download feature with flash memory? That way we wouldn't need a prom burner and everybody could implement waves themselves.

John Speth
Molectron Detector, Inc.
http://www.molectron.com
mailto:johns@...

On Sun, 16 Jul 2000, Paul Schreiber wrote:

> 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).

  Outfit the module with a flashrom that can store several, then use a
MIDI sysex interface on the panel to upload a wavetable.

> 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).

  Yah, pretty easy to do, though it will eat a lot of I/O pins real
quick..

Crow

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