3-10
BOPHV020411
C) This system can be calibrated to zero very accurately. For every configuration in which the
BOP is used, before checking or adjusting E
O
zero output, make sure that the input of the
BOP voltage channel is short-circuited to the signal ground. This can be done by connect-
ing together the front panel voltage channel input binding posts and the signal ground com-
mon, when the BOP is used as it is; or by connecting the signal ground common to the
external voltage channel input, when other external configurations for the pre-amplifier are
used. With zero voltage applied at the input, use a precision voltmeter to check for zero
volts at the output. If output is not zero volts, adjust E
O
ZERO.
3.3.2
REMOTE D-C VOLTAGE CONTROL BY MEANS OF D-C SIGNAL VOLTAGE
The BOP d-c output voltage can be controlled directly by a (±) 10V d-c signal, applied to the
front panel E
O
PROGRAM INPUT terminals. An interesting example of this application is the
BOP output voltage control with a Kepco Digital Programmer.
The connections between the Kepco Digital Programmer and the BOP are illustrated in FIG.
3-9. This programming system provides a resolution of 12-bits with a linearity of (±) 0.01%.
The digital and the power supply grounds are isolated (optical isolation) to 1000 volts. Calibra-
tion of the system is performed with the controls provided by the Kepco Digital Programmer.
FIGURE 3-9. DIGITAL CONTROL OF THE BOP D-C OUTPUT VOLTAGE
Since all terminals of the E
O
PRE-AMP are available at the REAR PROGRAMMING CONNEC-
TOR, d-c output voltage control can be exercised in many other ways. The E
O
PRE-AMP can
be treated as an uncommitted operational amplifier, with its applicable transfer-functions. Its ini-
tial offsets can be zeroed with the provided E
O
ZERO Control, while the offset variations are
specified in Section 1 of this manual (refer to Table 1-2). The basic principle of d-c output volt-
age control of the BOP is that a control voltage of (±) 10 volts at 1 mA at the E
O
PROGRAM
INPUT (with the built-in feedback/input resistors) will produce the full d-c output voltage swing of
the BOP. If the selected control signal does not have the required amplitude or if the required
control current cannot be supplied, the E
O
PRE-AMP configuration can be altered to provide the
proper interface for the application.
If, for example, the BOP d-c output voltage is to be controlled by means of a bipolar, 1 volt, high
impedance source, it can be connected to the BOP as shown in FIG. 3-10.