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5 – 4
Circuitry
U821 via the feedback resistor R819.
U823 is a photo-MOS switch that remains o
ff
during power-up until
the
±
15 V rails reach about
±
13 V. By then, the output of the Manual
DAC, which is driving the SIM960 output during power-up, will
have settled to near ground level and may be passed on to the output
connector BNC without large start-up transients. Until switch U823
closes, the SIM960 output is referenced to ground via R863 (100k).
U820A provides a bu
ff
ered analog output of the
P
×
ε
signal at the
back panel of the SIM960. Also, the output of U731A is passed to the
back panel to provide an analog output of the internally generated
setpoint signal.
5.2
Parts Lists
The parts list for the analog board is separate from the digital &
front-panel boards.
SIM960 Analog PID Controller