The 7075, with its simple to use controls and clear,
easy-to-read display enables the most inexperienced user to
discover that precise digital measurement is now within his
Automatic range selection means that there is, basically,
only one operator decision to be made - that of the quantity
to be measured : dc volts, ac volts or resistance. The
instrument instantaneously evaluates the order of magnitude
of the applied input and selects the appropriate range.
Ranging Points: (5 x 9’s)
Range-up > 140 000 digits reading.
Range-down < 12 000 digits reading.
N.B. Excessive series mode signals may cause range-up to
The facilities available are those of>
DC Voltage continuous range from Ιμν to lkV
AC (RMS) Voltage continuous range from l/iV to 750V rms
Resistance continuous range from ΙγπΩ to 14ΜΩ
True rms measurement: many instruments in the past presented
the mean value of an alternating quantity or if rms value
was displayed, it was arrived at by some method of
‘doctoring’ the mean value actually measured. The
disadvantage of that system is that validity of the reading
is very much dependent on waveform shape, only a pure
sinusoidal input giving acceptable results.
The 7075 is a true rms measuring instrument, in which the
input is directly converted to its root mean square at the
measurement stage. The displayed reading, therefore, is the
precisely computed rms value of the alternating quantity
A twelve decade display is used, bright and sharply defined,
no extraneous light being permitted to degrade the displayed
reading. The fixed decimal point and unique grouping of the
displayed digits makes possible an instant appreciation of
the order of magnitude of the reading thus obviating the
need for multiple and submultiple unit annunciators.
Scale length from 3 x 9*s to 7 x 9’s can be selected by the
user, the above being typical 7 x 9 s displays.
The display ‘moves’ to the right as the applied input
reduces in magnitude; leading zeros, except that to the
immediate left of the decimal point, are suppressed; and if
the quantity is negative the minus sign travels with the
display always maintaining its position immediately to the
left of the most significant whole digit.
The new conversion technique used is capable of obtaining
linearities two orders better than those possible using dual
ramp and related techniques. An important property of this
method is that the applied input is being continuously
averaged. Together with the very fast autoranging system,
this feature makes conventional filters, with their
associated problems, unnecessary. A new exclusive digital
filtering technique is utilised whereby the difficulty that
used to be associated with low frequency ac measurement has,
with the 7075, become a thing of the past.
Operator confidence is increased by a self check facility.
At the touch of a button the instrument can be commanded to
carry out a series of tests designed to prove the correct
functioning of all its circuits, displaying the result of
each check instantaneously.