Sample and Hold circuits

[Mikko Helin]

Look at http://www.paia.com/paia/fatmsch.gif, FatMan schematics, there's
4052 + .1 uF cap + non-inverting TL084 opamp, you could use 4051 which
is 8-channel analog multiplexer (4052 is 2*4-channel). 4051 cannot
handle negative voltages, but there may be other multiplexers
which can. Look for fast ones with very high off-resistance and
low on resistance. You better use CA3140's (rather than TL084) as buffer
opamps and buffer their outputs with other omamps (like TL084). There's
also a dual CA3240. With high input impedance and low input bias current
you don't have to update S/H's so frequently as they keep the charge
longer. Don't forget to use low-leakage caps, and remove flux after
soldering.


HTH,

Mikko