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439 Digital Current Integrator
The ORTEC Model 439 Digital Current
Integrator was designed to accurately
measure dc currents or the average value
of pulse currents such as produced by
accelerator beams. It digitizes the input
current by producing an output pulse for
specific values of input charge. A front-
panel switch permit the selection of three
different amounts of charge (10
10
, 10
8
or
10
6
coulomb) required to produce an
output pulse. The instrument has a
digitizing rate from 0 to 10 kHz to provide
wide dynamic range on each setting and
high-resolution readout without meter
interpolation.
The Model 439, when combined with a
preset counter, forms a digital charge
integrator. When it is combined with a
counter and timer, a digital electrometer
is obtained.
A front-panel meter is provided to read
the input current. Full-scale analog
outputs of 1 mA, 100 mV, and 10 mV are
provided on rear-panel binding posts.
Full-scale readings for the front-panel
meter and the analog outputs can be
selected in 15 steps from 1 X 10
9
to
1 X 10
2
A. The input is protected from
damage by application of a large input
charge.
Front- and rear-panel BNC connectors
are provided for the application of a Gate
signal to inhibit the digitized output. This
Gate may be used to remotely control the
Model 439 or it may be used to inhibit the
digitized output with a multichannel
analyzer dead time output signal.
Specifications
PERFORMANCE
LEAKAGE IMPEDANCE FROM INPUT TO
GROUND >1 X 10
10 .
INPUT LEAKAGE CURRENT <1 X 10
12
A.
TEMPERATURE INSTABILITY ±0.05%/°C,
0 to 50°C.
DIGITIZED OUTPUT INACCURACY
Readings from 100 nA to 10 mA dc, ±0.2%;
for 50 nA, typically ±0.3% (count rate on 10
10
coulomb/pulse range limited to 1 kHz).
DIGITIZED REPRODUCIBILITY 0.01%.
ANALOG ACCURACY Front-panel meter 2%;
rear-panel binding posts 1.5%.
CONTROLS AND INDICATOR
MULTIPLIER Front-panel switch determines
the multiplier to be applied to the Current F.S.
reading to produce a full-scale deflection on
the Ampere Meter.
CURRENT F.S. AND COUL/PULSE Front-
panel switch, controls amount of charge that
must be injected at the input to obtain a digital
output pulse (low, medium, and high selection
for each).
TEST-OPERATE Front-panel 3-position switch
controls the function of the Model 439:
Test Internal test current is provided to
produce an output of ~1000 Hz on all
coulomb/pulse ranges.
Standby Grounds the input of the Model 439
preventing application of transients to the input
amplifier.
Operate Position in which the Model 439 will
normally be used; connects the input amplifier
to the front- and rear-panel SHV input
connectors.
POLARITY Front-panel switch selects the
polarity, Pos or Neg, of the input current to be
measured.
BAL/TRIG Front-panel switch used in con-
junction with Bal/Trig Meter and Test- Operate
switch balances and adjusts the Model 439
input amplifier.
OFFSET/CURRENT Rear-panel potenti-
ometer adjusts the input offset current over a
range of ~±10 pA.
INPUTS
SIGNAL INPUT Through front- and rear-panel
SHV connectors.
Impedance Virtually ground with maximum
excursion of <±5 mV.
Current Polarity Positive or negative.
Current Range 1 X 10
9
to 1 X 10
2
A. Measures dc or average value of
pulse currents Usable as digital current integrator,
digital charge integrator, or digital
electrometer Wide dynamic range Input protected to ±1000 V (0.01 µF)
or ±2000 V (0.001 µF)
ORTEC
®
439
Digital Current Integrator GATE Signal normally enabled in absence of
an input or when the dc value is nominally
+6 V; front- and rear-panel BNC connectors.
To Enable Output +3 V or greater.
To Inhibit Output +1.5 V or less (e.g., can be
shorted to ground by a relay).
Maximum Input +25 V, 10 V.
Duty Cycle Limitation None, dc-coupled.
Input Impedance >1000 ; driving source
must be capable of sinking 1 mA of current
from a positive source.
OUTPUTS
DIGITIZED Signal +5 V, 500 ns wide; 0 to
10 kHz; front- and rear-panel BNC con-
nectors.
ANALOG
Front-Panel Meter 01 and 03 scales
serving all multiplier ranges. There are 15 full-
scale ranges.
Rear-Panel Binding Posts 0 to 1 mA full
scale; 0 to 100 mV full scale; 0 to 10 mV full
scale. There are 15 full-scale ranges.
ELECTRICAL AND MECHANICAL
POWER REQUIRED The Model 439 derives its
power from a standard NIM bin/power supply,
such as the ORTEC Model 4001A/4002A.
Required power is +24 V, 45 mA; 24 V, 45 mA;
+12 V, 95 mA; 12 V, 110 mA.
WEIGHT
Net 1.7 kg (3.75 lb).
Shipping 3.06 kg (6.75 lb).
DIMENSIONS NIM-standard triple-width
module 10.28 X 22.13 cm (4.05 X 8.714 in.)
front panel per DOE/ER-0457T.
Related Equipment
The Model 439 may be combined with an
ORTEC preset counter to form a digital charge
integrator or with a counter and timer to form a
digital electrometer.
Ordering Information
To order, specify:
Model Description
439
Digital Current Integrator
Typical Current Digitizing System
439
Digital Current Integrator
Tel. (865) 482-4411 Fax (865) 483-0396 ortec.info@ametek.com
801 South Illinois Ave., Oak Ridge, TN 37831-0895 U.S.A.
For International Office Locations, Visit Our Website
www.ortec-online.com
Specifications subject to change
080107
ORTEC
®