GB701851A - Electrical pulse circuits - Google Patents

Abstract

701,851. Digital electric calculating apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Sept. 18, 1952 [Sept. 26, 1951], No. 22541/51. Class 106 (1) [Also in Group XL (c)] A modulus two adder comprises at least two ring modulators connected in cascade and arranged to be controlled by electrical digit pulses to be added, the first ring modulator being arranged to be fed with short electrical interrogating pulses. The circuits described give the digit of least significance of the binary sum of the digit pulses applied. In an arrangement for adding two binary digits applied at inputs 1 and 2, two ring modulators are biased so that current through the rectifiers reverses when the respective input changes from zero volts (digit "o") to V volts (digit "1"). A short, positive-going interrogating pulse applied via an input transformer T1 midway between the changeover points of the binary digit inputs, causes a positive-going or negative going pulse across the common inductor 2 according to whether a "0" signal or a "1" signal is present at input 1. Similarly, the pulse appearing across the inductor 2 will cause a pulse of like or opposite polarity across a transformer T3 according to whether a "0" signal or a "1" signal is present at input 2. To overcome the effect of possible spurious output pulses a biasing pulse is applied to the centretapping of the secondary winding of transformer T3, and the cathode of a double triode VI, V2 is biased so that one side conducts only when the grid voltage exceeds the bias voltage V. The output is registered on a trigger pair V3, V4. Instead of the common inductor 2 between the ring modulators, a transformer counting may be used. The circuit may be extended for more than two inputs by employing further transformers and rectifiers. The rectifiers may be thermionic, crystal diodes, or metal rectifiers.