4051 mux problem?

[The Dark force of dance]

Y-ellow Stewart, Paul 'n' y'all.
	I don't know if this is of any help to you but in my limited experience
with sample hold, I've found using an integrator to be far more successful
than buffering a cap. The output of the opamp holds the capacitor rock
stable at what ever the last input voltage was. Over a time constant of
course but your caps can be ultra small.

The output is inverted of course but you can elect to do one of two things.
Throw another inverter on the end or simply invert your numbers from the
micro. If your op-amp is good and your leakage is low you can hold these
things for hours. Days in some cases with a very careful design. Though I
can't say I've actually achieved this. Milliseconds are usually sufficient.

An integrator is  more or less a capacitor placed in the feedback loop of
your op-amp. One end goes up, the other goes down. The potential difference
in between effectively locking the output voltage over a time constant set
by the capacitor. Shorting the capacitor clears it. Presenting a new
voltage to the input changes it. If the capacitor is small then the time
constant for change is small. The ability to track/hold is a function of
the quality of the components no the size of the capacitor.

Hope this helps.

Be absolutely Icebox.

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