Two of twelve sample and holds

Here is a CGS SSG board, assembled as a dual S&H with a one-shot circuit.  It’s the first of six identical boards for use in the Quantasise.

ssg-dual-shThe SSG (Smooth & Stepped Generator) has two virtually identical sections that can each function as a VC slew, VCO, or Sample & Hold.  The S&H function is implemented by negatively pulsing the Hold input.  A pulse releases the hold for a moment, allowing the output to slew towards the input and then hold again.  The minimum acquisition time obtainable with the selected capacitor is about 0.28 milliseconds, relatively long for a S&H, but it works just fine for my purpose.  No external rate pot is needed, because the trimmer is capable of setting the rate for the shortest acquisition time.  I selected a 47 nf polypropylene capacitor for the integrator.  This  capacitor is Mouser part number 505-MKP20.047/100/5 (WIMA MKP2D024701C00JSSD).

In addition to the two S&H circuits, each SSG includes two one-shot negative pulse generators.  The one that produces a pulse on both positive and negative phases of the cycle is used to drive two S&H circuits, as shown in the Quantisise block diagram.

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