Variable time constant frequency meter with MECL integrated circuits

The point of interest of this frequency meter is that its accuracy is fixed in advance for the whole frequency range which is to be measured. For this, it is possible for the measurement range to be changed several times by changing the time constant which varies over discrete values and adopts that corresponding to the measured frequency for a given accuracy. The frequency meter which we present here gives three values of the accuracy, i. e. three groups of variable time constants, and operates as a chronometer and as a conventional frequency meter. The object is to describe the construction of a variable time-constant system and it is obvious that further work would lead, because of new industrial circuits, to great improvements in the design of the apparatus. (authors)