Tom Pratum writes :
"...... This modification
was simply to replace the 1 microfarad capacitor on the output of the
analog switch which gates the homospoil into the z shim on the low
current shim amplifier board with a 0.1 microfarad capacitor. ..."
We took even more drastic steps an just removed this capacitor and replaced
the 15nF capacitor in feed back loop of the op-amp by 1nF. If you are eager
to get reallly short recovery times you might want to try this. Actually we
even replaced the op-amp by another model (NESS34AN). We could never detect
any ill effects on the z-shim. But it is probably a good idea to a run hump
test before and after the modification and check the stability of the z-shim.
Gerhard Wider
ETH-Zurich
Email: gsw@mol.biol.ethz.ch