[sdiy] Walsh Generator & demo board

[Tony Allgood]

Hi Tim and All,

>It takes a clock in, and produces 15 sin and cos Walsh functions. I am
considering offering it for sale, along with a little demo PCB which has
a 8 (or more?) input mixer for summing the Walsh functions.

First thing that you should know is that the walsh outputs need to be
bipolar. Or at least mixed in a fashion so as not to allow the sumnation
of the wal outputs to affect the DC offset. So just summing TTL type
square waves wrt ground is not going to work properly.

Second thing, is that the mixer should be a reversible attenuator type.
Many types of waveforms, symmetrical ones about OV IIRC, use some
inversed wal outputs.

Third thing is that for bass notes to take on any real power you really
need 31 walsh outputs. I found 15 not as interesting and a little
'electronic'.

But you know the biggest problem with any walsh bank is not the
generation of the walsh series. This can be done pretty simply with
about eight or so cheap HCT chips. The problem is mixing them, and
controlling the pitch over a decent musical range.

Still think that all of this needs to be done in software as a virtual
synth.

Regards,

Tony Allgood                       Penrith, Cumbria, England

Oakley Sound Systems                     www.oakleysound.com
Modular projects            www.oakleysound.com/projects.htm