[sdiy] 555 timer adsr

[James Dunn]

Hi,

I'm currently working on a 555 timer based ADSR, but the output doesn't 
seem to ever completely reach 0v. I saw this schematic online:
http://www.uni-bonn.de/~uzs159/vcadsr.png

can someone tell me how I would connect the diode as specified at the 
output op-amp? I assume a 1n4148 would suffice? The circuit I'm using 
is slightly different (TL071 on the output) but I'm hoping this might 
work!
thanks

James