Hi,


> 3. Harris (Intersil) HCA125ACREF. It's 200 watts!!!  I find it very
funny
> that you mention this one.  They want a $10K license fee, plus
royalty.
> :(   If you've got data on this I'd like to see it.  I don't beleive
that
> they are making info available other than a brief description, but
that
> wouldn't matter if they don't want to sell the controller.

When Harris was experimenting with Class D amplification some years
ago, they published a couple of design notes plus a 200W reference
design using standard Harris parts. I guess that in these days they
weren't really aware of the great commercial strength the concept had
in it. Today however they do. IIRC they now call it COOL AUDIO and you
may only use it on license bases.
That was the reason I said 'I'm not sure if these papers are still
online'.
I probably have some PDF's somewhere on this topic. I could mail you
them if you're interested.

> 5.  Unitrode UC3879.  I had already looked at this.  Do you think it
would
> work well as a class D audio amp?

Actually I didn't advice that part for building a class D amp, I only
pointed that way for more info about phase shifted PWM technology used
for ZVS.
However there may be some possibilities to make a class D amp with
this part. The drawback of this part is the lack of flexibility to
access the onchip connections which are handy in a class D amp. It's
optimised for building power supplies. A Harris full bridge driver
(HIP4080) with build in error amp could do the job very well.

> Of course, I would still use a PIC to generate the siren sounds and
do
> other slow tasks.

That's indeed less demanding :)

Bye,

Daniel...