[sdiy] LF398 sample and hold ?'s

[René Schmitz]

Hi Derek and all!

>then i looked at Rene Schmitz's YASH sample-and-hold circuit ( 
>http://www.uni-bonn.de/~uzs159/ ) and saw a pile of gates and an extra 
>transistor leading into the logic input pin. what exactly is all that for if 
>all you really need to do is trigger it with a push-button switch? i'm 
>curious...

The thing is you don't only want to trigger it manually. I even think I
almost 
never want that. (If I wanted a push-button operated S&H I could think of a
better 
way, than steering an electric switch with a mechanic switch...)

The S&H is best used if you say trigger it from a sequencers 
lock, or from an LFO or so. These gates are there to make a short, so that
the 
signal is sampled for a short duration (3uSec or so), and automatically
goes to 
hold mode again. The transistor and the first gate are for a level
translation, so 
that one can use 5V logic as well.
I made it a relatively short aperture time so that one can trigger 
the S&H very rapidly, to make aliased "undersampling" noises in the audio
range.

Hope this helps,
 René




-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159