[sdiy] New Echo Delay module

[sbernardi at attbi.com]

Made up a new module based on the Princeton PT2399 
echo/delay chip, which I obtained for $3.95. It's a 
digital delay used in karaoke machines and such.  I 
voltage controlled it by using a homemade LDR (LED and 
CDS photoresistor). 
It actually works pretty well. I've got schematics, 
datasheet, and a source for the PT2399 on my web site
http://home.attbi.com/~sbernardi/elec/og2/og2_home.html 
and go to the What's New page. Sorry, no sound files yet.

The PT2399 is spec'd for 300mS with 1% distortion; I'm 
pushing it way past that (up to 2 sec) but it still 
sounds interesting.
I also have a PT2395 which uses an external 256 DRAM 
chip to give longer delays. Eventually I'll make a 
module out of that, too.