Options-7844/R7844 Operators
Readout Mode Switch ( Internal)
The two�position Readout Mode switch determines whether
the readout display mode is dependent on the front-panel
controls ( Free- Run model or is in the Gated mode (see
Figure 4-1 ). I n the Free-Run mode (marked F . R . on circuit
board) the readout display is dependent on the setting of
the front·panel R EADOUT controls. When the internal
switch is set for Gated operation (not marked on circuit
board) readout is displayed at the end of beam 2 sweep, in
dependent of front-panel R EADOUT control settings. The
internal switch is only recommended for use with single·
sweep photography when raster scanning is not desired. For
further information, see the Display Photography discussion
in this section.
READOUT MODE
SWITCH
(521 10)
GATED
F.R.
(FREE R U N )
NOTE
THE READOUT CIRCUIT BOARD OS LOCA
TED ON THE RIGHT SIDE OF THE 7844
AND IN THE TOP RIGHT CENTER O F THE
R7844.
Fig.
4-1.
location of Readout Mode Switch on the Readout circuit board.
Display Photography
The 7844/R7844 Option 22 increases the photograph ic
writing speed for single-sweep photography of fast transient
signals. To use the writing speed enhancer, set the R EAD·
OUT I NTENSITY/PULSED ENHANCER control to the
PULSED detent. Set the E N H AN C E R P R ESET by experi
menting with the waveform photograph. When the EN HAN
CER PR ESET level is low (counterclockwise) the photo
graph background will appear black and the fast-rising por
tions of the waveform may not develop. As the E N HA N C E R
PRESET level is increased ( i n a clockwise direction) the
photograph background will approach grey and the addition
al light supplied by raster scanning should produce a visible
image on the fast-rising portions of the photograph. How
ever, if the E N HANCER P R ESET level is set too high, the
background exposure approaches the trace exposure which
makes the photograph unusable.
4-2
If the photographic application does not require enhance·
ment and pulsed readout operation is desired, the EN HAN
C E R P R ESET control can be set counterclockwise to
e!iminate the raster scan display. Another method to pro
duce pulsed readout without the raster scan display, is to
set the front-panel R EADOUT I NTENSITY /PU LSED EN
HANCER control out of switch detent (non-pulsed opera
tion) and set the internal Readout Mode Switch to Beam 2
Gated; however, the instrument cover must be removed to
gain access to the switch. The internal Beam 2 Gated
switch must be set to F R ( Free Run} for normal operation
of front-panel READOUT controls. See Fig. 4-1 for Read
out Mode Switch location.
REV.
A, MAY, 1975
