GB892894A - An electrical system for a stepwise control of a plurality of drives - Google Patents

Abstract

892,894. Electric selective signalling systems. ELEKTRO-MECHANIK G.m.b.H. Feb. 26, 1959 [Feb. 27, 1958], No. 6692/59. Class 40 (1). In a system for controlling the position of a shaft driven by a motor 22, Fig. 1, each depression of a button 11 advances the shaft by one step and each depression of a button 12 backs the shaft by one step. A button 13 is also provided which returns to the shaft to its reference position in one single operation. The desired position of the output shaft is determined by counting, algebraically, the depressions of buttons 11, 12 on a counter 17 comprising relays A, B ... K. This counter being such that after one depression of button 11 the single relay pair A, B are picked-up, after two depressions the two pairs A, B and C, D are picked-up, and so on, and selecting, by the contacts of relays A, C, E ... J, a corresponding voltage from a potential divider chain of resistors I, II ... VI which is applied via a line 19 to a comparator 24. The other input of the comparator comes from a further and similar potential divider the tapping point being selected by a drum 21 driven by the output shaft. Lack of agreement of the two voltages applied to the comparator drives the motor either forwards or backwards via relays 25. In a modification the two potential dividers are replaced by an arrangement of contacts.