More on Fav Designs - ADSR envelope controller / digital (gas p!)

[David Halliday (Volt Computer)]

> The 3310 EG
> =========
> 
> All agree, this is the chip. So concern over the availability. Gene, I
> GOT
> 1200!! Now, this is certainly enough for now. So don't be shy using
> it. I
> will design an equivalent from discrete later this year.
> 
> 
> Once again, what about using a uP for generating the envelope? Trade
> offs?
> 
> 
> [Dave Halliday]  Adding my $0.02 worth - this is an application where
> the PIC chip would excell...  It has several A/D inputs ( 8-bit )
> which can read a pot directly.  It has several digital and analog (
> 8-bit again ) outputs.  You can also input a lookup table through a
> serial port to your PC or to a MIDI storage device...  The outputs can
> be either control voltages or a pulse-width.  You could probably gang
> several outputs together to generate a greater than 8-bit resolution
> but I bet that for general amplitude control, 8-bit would be
> acceptable for most cases especially if you filtered the control
> signal to minimize zipper noise.
> 
> 
> Power Supplies
> ===========
> 
> It's hard to beat a 723/D40xxxx pass transistor. 
> 
> 8< Snip! 8<
> 
> What about switching supplies in analog designs? Too much voltage and
> current ripple?
> 
> [Dave Halliday]  plus lots of hash from the supply - I tried this. A
> friend found a *huge* +15/-15 switching supply ( 12 amps per side )
> and I tried running some of my modules from it.  The switching speed
> was in the 100KHz range but there was a lot of noise in the audio
> output that was not there on batteries or my analog supply.
>