vc wave select

[tomg]

> May I add my own two cents (or whatever the relevant currency is).  I
agree
> with Tom G. that this is an interesting design approach and worthy of
> consideration.  I agree with Jorgen that the resulting design is a little
> "wordy" and needs some work.  For analog switches, I much prefer the
> 74HCT4051/2/3 series.  The logic runs between 0 and the + voltage, and
the
> signals can range between the + ad - voltage, typically +/- 5 to 7.5
volts.
> Since the control voltages draw zero current the +/- supplies can just be
> resistive dividers.

I have a lot of 4016/66s so I tend to design for what I have, although you
are absolutely correct about the 4051/2/3 series.
 
>     The use of 74X30's for decoding purposes is a little unfortunate. 
For
> ultimate versatility, some kind of PLD is called for.  Twenty-pin EPLD's

Again you are correct but 74X30s are a quarter each.

> (GAL16V8) are available for less than $2 US and can have up to eight
outputs
> and up to 16 inputs.  The 20V10's are still grossly overpriced at about
$5.
> Both require programmers.  What has caught my eye is the new Xilinx CPLD
XC9530
> family.  The smallest, the XC9536 has 36 macro cells and comes in a
44-pin PLCC
> package.  It costs less than $3, requires no $1000 programmer ( it uses
ISP (In
> Circuit Programming).  Xilinx points you to a development kit for $100
with all
> the compiler software you need plus a demo board with switches and LEDs
and a
> cable that connects to the printer port for programming.  I think this is
a
> super bargain.  The slowest parts are 15 ns.  For about $2 more you could
get
> an XC9572 with 72 macrocells.  Digikey sells the parts.  A distributor
called
> Insight has the $99 kit.  Check it out.
> 
> Gene Z

WOW! Jeez Gene... thats a little more versatility than I wanted to deal
with, but 
thanks and I'll keep it in mind for the M12. By that time I should be good
enough 
to do something like that.....;-) For now I think I'm happy with my $5
switch.

-tg ( "I'm no Dr. Moog" damm I aint even a Gene Z or a JH but I have fun! )