GB735942A - Improvements in or relating to electrical counting apparatus - Google Patents

Abstract

735,942. Electronic counting apparatus. CINEMA-TELEVISION, Ltd. Aug. 28, 1953 [Aug. 28, 1952], No. 21635/52. Class 106 (1). In an electric counting apparatus comprising a chain of four binary counter stages having feed-back paths to produce an effective scale of ten, points in each stage which suffer predetermined voltage excursions when the stages are operated, are connected through resistors to one terminal of a current meter whose other terminal is maintained at a fixed potential, whereby the indication of the meter corresponds to the number counted by the chain. Negativegoing pulses entering at a terminal A step the binary chain of trigger pairs 1, 2 . . . in the usual way until the eighth pulse reverses the trigger 4. This causes negative pulses to be fed back to stages 2 and 3, reversing them again so that the chain now represents a binary count of 14. Thus two more input pulses complete a cycle and bring the chain back to its initial condition after ten input pulses. A " carry " pulse for transfer to the next decade appears at a terminal B. Resistors 14, 15, 16, 17 connecting the R.H. anodes of each trigger pair with a centre-zero meter 18 are selected to pass currents to the meter in the ratio 1 : 2 : 4 : 2, respectively, when the associated valves are non-conducting, and corresponding currents away from the meter when the associated valves are conducting, the other terminal of the meter being connected to a potentiometer 19 adjusted to a potential mid-way between the two possible potentials at the anodes of the valves. With this arrangement the algebraic sum of the currents passing through the meter increases in equal steps from a count of zero to nine, so that the meter provides an indication of the number of pulses counted. Instead of a centre-zero instrument, a normal meter could be used after appropriate adjustment of the potentiometer 19. Specification 572,884 is referred to.