EG&G ORTEC 442 Panduan Pengoperasian dan Servis - Halaman 9
Jelajahi secara online atau unduh pdf Panduan Pengoperasian dan Servis untuk Alat Ukur EG&G ORTEC 442. EG&G ORTEC 442 16 halaman. Linear gate and stretcher
Halaman Cetakthe discriminator threshold, the discriminator may be
fired or it may sti l l be set because of not having recovered
from a previous input pulse. The linear input pulse will
not be accepted unless the discriminator has recovered
prior to the new pulse; it wi ll also be rejected if (1) an out
put pulse has not been completed for a previously
accepted input; (2) the operating mode is gated coinci
dence and no Gate Input has been furnished; or (3) the
operating mode is gated anticoincidence, a Gate Input
signal has been furnished, and the Gate Period is in effect.
When the discriminator recovers, it will permit the input to
be gated on unless (1) the output pulse has not been
completed or (2) external Gate Input logic has closed the
l inear input circuit. When the output pulse has been
completed, the l inear input is permissive unless (1) the
discriminator is not reset or (2) external Gate Input logic
has closed the l inear input circuit.
When the discriminator is triggered prior to a Coincidence
Gate Input but the l inear input is otherwise permissive, the
l inear input signal is not applied to the stretch circuit
until the Gate Input signal is furnished. Under these con
ditions, the l inear input signal is applied to the stretch
circuit at the Gate Input time; an output signal will result,
which has an amplitude equal to (1) the peak input
amplitude or (2) the input amplitude at the end of the
adjusted Gate Period (whichever occurs first). Thus, it is
important that the gate be triggered during the rise time
of the l inear input pulse and that it remain effective until
after the peak amplitude has been sensed.
5. CIRCUIT DESCRIPTION
This section provides a brief description of the basic
functions of the 442 and the circuit diagram. Reference
is frequently made to Fig. 5.1 and to schematic 442-0101-SI
(at the back of the manual).
5.1. DC RESTORER
The input section of the 442 is a dc restorer that can be
by-passed by selecting DC-Couple with switch SI. If dc
BIK LOW
restoration is desired, restoration can be selected for either
a low or high count rate by SI. The low restoration rate is
approximately 5 mV//isec, and the high rate is approxi
mately 150 mV/^isec. The restoration currents for the low
and high modes are approximately 100 ijlA and 3 mA
respectively. The restoration rate can be readily changed
by changing the vaiue of C1. The restoration circuit is
composed of Q1, Q2, Q58, and Q59.
OUTPUT
oil! UIGH
STRETCH
AMP
RESTORER
COUPLE
ADJUST
BUFFER
ANTi-CQiNC
CONTROL
PULSE
DELAY
AOi.
PULSE
WIDTH
AOI.
LOGIC
. R 94
Fig. 5.1. Block Diagram of Model 442 Linear Gate and Stretcher.