BWD Electronics 845 Oscilloscope
Dual trace Storage Oscilloscope
The BWD 845 is a high performance, portable variable
oscilloscope. It incorporates a delayed, mixed or delayed
trigger time base, vertical amplifiers with a ImV
sensitivity on both channels and can be powered by AC, DC or
an optional battery pack.
The variable persistence/storage facility enables the user
to view and measure intermittent signals and transients that
cannot be detected on a normal Oscilloscope
. It also retains
wave forms at very slow sweep speeds allowing the entire
waveform to be viewed rather than a moving dot. If
persistence is adjusted to overlap traces, fast signals at
low repetition rates can be integrated to make, them readily
visible;. This technique makes it possible to view and store
signals that are faster than the CRT writing rate, in fact
up to 30MHz.
Storage oscilloscopes are more complex than non-store
models, so several features have been incorporated to
simplify the comprehensive facilities provided.
A standard feature of all BWD oscilloscopes is the ALL
BUTTONS OUT condition for normal operation. This is
incorporated in the BWD 845 and is a major contribution in
An AUTO ERASE cycle eases the task of setting Up the CRT
controls in the storage mode. View time is approximately 4
seconds after each writing sweep is completed. It is then
erased to await the next sweep. In the CHOP mode two tracés
müy be written and viewed simultaneously or alternately in
the ALT mode. This mode may also be used for viewing
repetitive single shot signals that contain non-repetîtîve
When a long waiting time occurs before a signal is received
to trigger the time base and write a stored display the
screen may fade green all over.
An AUTO STORE facility in the BWD 845 eliminates this
problem by holding the CRT in the erase condition until the
time base is triggered by a signal, thus extending the
pre-trigger period to hours instead of minutes. It then
automatically switches to store and a LED indicator
signifies this condition.
The CRT characteristics themselves form the major control on
writing speed and storage. It has a burn resistant screen
and operates at 7.510/ EHT to provide a well focused trace
in all operating modes. To optimise its operation for both
fast writing and long viewing/storage times, two switch
selectable settings are provided - slow or fast. By writing
in fast then switching to the lower intensity slow
condition, storage or viewing times can be greatly extended.
The backing electrode is also adjustable over a limited
range by the front panel background control for best signal
to background contrast.
The combination of these wide range storage and Oscilloscope
functions make the BWD 845 a very powerful tool for a wide
range of measurement and analysis.
Service and User Manual
5.47 Mbytes (5733218 Bytes)
01 January 1977
Scanned document, reading partly badly, partly not readable.
04 June 2017