[sdiy] New cheap FPGA development system

[Eric Brombaugh]

Jim Patchell wrote:

 > NCO's are something I have been experimenting a lot with for a DIY 
digital synth...

NCOs are cool. I built my first one (24 bits, 12 MHz) with LSTTL and 
wire wrap back in 1985. I found it in the garage the other day while 
looking for something else. I've used them over and over again in 
wireless comm ASICs and the DVCO project I mentioned a while back is a 
software NCO.

They aren't all sweetness and light though - although you can get 
frequencies approaching Nyquist from them they suffer badly from phase 
jitter. There are ways around that, but they cost more gates and 
introduce other issues.

Eric