Emerson 755A - Manual (Page 65)

Instruction Manual
245364-V
May 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Circuit Analysis 5-11
Model 755A
5-7 BUFFER AMPLIFIERS U10 AND
ASSOCIATED ANTICIPATION FUNCTION
Refer to Figure 5-9 below. U10 is a non-
inverting buffer amplifier that incorporates an
anticipation arrangement in its input network,
thus providing slightly faster response on the
readout device(s).
Potentiometer R30 provides a continuously
variable adjustment of 5 to 25 seconds for the
electronic response time (90% of fullscale)
and is factory-set for 20 seconds.
Since the anticipation network attenuates the
signal, a gain of 10 is provided by the
feedback network associated with U10 to
restore the signal to the desired fullscale
range of 0 to 10VDC.
The pressure-corrected output signal from
U10 is routed to two output circuits:
• Digital Output Circuit, Section 5-8 on page
5-12
• Analog Output Circuits for Recorder and
Alarms, Section 5-9 on page 5-12
Figure 5-9. Buffer, Anticipation, and Digital Output Circuit
-
+
U10
R30
R29
Differentiator
Network
ADC
71C03
8052A REF
DISPLAY
DRIVER AND
CONTROL
+15V
5V
U18
5V
REGULATOR
To Analog Output Circuit
(Figure 6-9)
DIGITAL
DISPLAY