GB883897A - Improvements in or relating to electric pulse counting circuits - Google Patents

Abstract

883,897. Electronic counting-apparatus. GENERAL ELECTRIC CO. Ltd. Nov. 19, 1959 [Nov. 28, 1958], No. 38459/58. Class 106 (1). [Also in Group XL (c)] In a binary counter comprising a plurality of cross-coupled bi-stable transistor stages, the input pulses are supplied to all the stages via gates, each gate being controlled by the stages of lower order. As described, a binary counter comprises four stages 2-5 each comprising a pair of P-N-P junction transistors such as 6, 7, cross-coupled in known manner to form a bi-stable circuit. Input pulses to be counted are supplied from a source 1 via a transformer 16 to the first stage via a line 8 and to subsequent stages via a line 19. A " 0 " is represented in each stage by the right-hand transistor thereof being in a conducting state. In each stage there are provided gates 9, 10 arranged so that each pulse applied to the stage causes it to change to its other stable state. Gating devices 20-22 are provided for gating pulses to the three higher stages. The gating device 20 comprises a transformer 26 which passes a pulse to the associated stage 3 only when a transistor 28 is biased to be conducting. The transistor 28 is controlled through diodes 35, 36 such that when the transistor 7 of the first stage is conducting, the transistor 28 is maintained cut off, but when the transistor 7 is cut off, the transistor 28 is maintained conducting. Transistors 33, 34 are provided as emitterfollowers. The gating device 21 is controlled through diodes 42, 43 to pass a pulse to the stage 4 only when the stages 3 and 2 register a " I." The gating device 22 is similarly controlled by a diode gate 46. A network 37 is provided to reduce the voltage swing applied to the base of the emitter-follower transistor 34. Additional binary counting stages may be provided if required. The circuit may be adapted as a binary-coded decimal counter by changing over switches 39, 59 and 60, a gate 63 being opened when the stages 2 and 5 both store a " 1 " (i.e. 9 pulses have been counted), an emitter-follower 64 thereby producing an output pulse between the ninth and tenth input pulses. The gating device 22 is conditioned to pass the tenth pulse to the stage 5, thus zeroizing the circuit. A second decade state may be provided (Fig. 2, not shown). Outputs from the bi-stable stages may be arranged to give an output signal when a predetermined count is reached.