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 grasp. 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 occur earlier. ja«! 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 (l.lkV Peak). 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 being measured. 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.