GB1297111A - - Google Patents

Abstract

1297111 Rotary angular transducer recording apparatus DEFENCE, SECRETARY OF STATE FOR 10 Dec 1969 [5 Oct 1968 30 Nov 1968] 47314/68 and 56974/68 Headings G1J and G1N [Also in Division H1] A continuously rotatable and reversible angular position transducer suitable for indicating wind direction comprises a rotary potentiometer and switching means operable in dependence on rotor position to switch the input supply from a first position in the potentiometer arrangement, AB in Fig. 1, to a second position CD. The arrangement avoids the continual wide variations in output signal which would otherwise occur when the motor vacillates near input terminals. As shown, a rotor contact 3 sweeps contacts studs between a number of equal resistors forming a rotary potentiometer. On opposite sides of the potentiometer diodes, 78 are provided whose forward resistance is equal to the resistors and an input supply 12 is fed either to AB or to CB through a change over relay 9 controlled by a magnetic reed switch 11 actuated by a magnet 14 in dependence on motor position. Output is taken from a fixed terminal 16 (or potential-divider) and the rotor at 15 and fed to a recording instrument, Fig. 1a. Fig. 2 (not shown) discloses by an outer ring of numbers the voltages relative to terminal 16 (North) for a 17v. supply at AB, and by inner numbers for a supply at CD. With supply at AB clockwise rotation from 100 degrees causes the voltage to step from -13v. at 100 degrees, through -19v. at 180 degrees, -5v. at 260 degrees, 0 at 0 degrees to +4v. at 80 degrees. Reed switches 11 now operates to change the supply to CD and further rotation gives +5v. at 100 degrees, +9v. at 180 degrees and +13v. at 260 degrees. At this point the relay again operates returning the supply to AB and a sudden change to -5v. arises on further rotation to 280 degrees. Two ranges of 360 degrees are thereby provided as shown in Fig. 1a these overlapping by 180 degrees. The supply positions need not be diametrically opposed, but should remain in a symmetrical relationship about the fixed tapping. Alternative methods of operating the change over relay 9 are disclosed in Figs. 10 and 11 (not shown). In Fig.3 (not shown) the switching arrangement is a bistable transistor circuit operated when the contact studs at AB or CD are bridged. Magnetically operated switches, Fig. 4 (not shown) on lightsensitive switches, Fig. 5 (not shown) or camoperated switches, may replace the rotary brush 3. In a modified system, Fig. 6, the supply positions are alongside each other and a switch arm 22 is arranged to close to a terminal 17 when a makebefore-break contact bridges terminals GE, and to terminal 19 when it bridges EF. Again two ranges are provided but in this instance they do not overlap, Fig. 6a (not shown). A member of arrangements for effecting the switching in dependence on the motor position are disclosed, Figs. 7,8, 9 (not shown).