--- In korgpolyex@yahoogroups.com, "tim.tashpulatov" <tim.tashpulatov@ ...> wrote:
>
> Hi all, I am new to the group, am expecting my newly bought Poly-800 to arrive, and considering to buy HAWK-800 upgrade.
>
> I've read through the list of HAWK-800 features, and would like to know how this Random Sample & Hold thing works. Any samples to illustrate its usages? Thanks.
>
It makes random beepy noises. "Sample and Hold" refers to the act of sampling an incoming voltage at a particular instant, and then holding it for a certain length of time. Take a look here:
http://www.super- freq.com/ ?p=89
In the first circuit diagram the 555 timer is an LFO that generates a very narrow pulse. This switches on the FET in the middle (marked G/D/S) which conducts for an instant. The capacitor connected to "D" charges up to whatever voltage is coming in from the noise source at the top almost instantly. When the FET switches off, the capacitor stays charged. The other FET forms a high-impedance buffer so that the cap doesn't discharge quickly.
The upshot of this is that you have a random voltage from the white noise source, but you hold the output at a particular level for a time depending on the speed of the LFO. These days, of course, it's all done in software - which is how the HAWK-800 can do it ;-)