US3631328A

US3631328A - Electronic control marine searchlight

Info

Publication number: US3631328A
Application number: US1082A
Authority: US
Inventors: Gaylord M Borst; Robert A Booty
Original assignee: Outboard Marine Corp
Current assignee: Outboard Marine Corp
Priority date: 1970-01-07
Filing date: 1970-01-07
Publication date: 1971-12-28
Anticipated expiration: 1988-12-28
Also published as: CA956013A

Abstract

Disclosed herein in a searchlight which is supported for movement about horizontal and vertical axes and a control member for remote operation of the searchlight. The control member is supported for movement about first and second or horizontal and vertical axes corresponding to the axes of the searchlight and is connected to vertical and horizontal position sensing potentiometers which form part of an electrical circuit. The electrical circuit includes transistor preamplifiers and transistor switches which control operation of horizontal and vertical position electric motors which are connected to the searchlight and which move the searchlight to a position corresponding to the position of the control member.

Description

United States Patent inventors Appl. No.

Filed Patented Assignee ELECTRONIC CONTROL mam:

2,719,254 9/1955 Clemence et al.

ABSTRACT: Disclosed herein in a searchlight which is supported for movement about horizontal and vertical axes and a control member for remote operation of the Searchlight. The control member is supported for movement about first and second or horizontal and vertical axes corresponding to the axes of the searchlight and is connected to vertical and horizontal position sensing potentiometers which form part of an electrical circuit. The electrical circuit includes transistor preamplifiers and transistor switches which control operation of horizontal and vertical position electric motors which are connected to the searchlight and which move the searchlight to a position corresponding to the position of the control member.

1 ZOO PATENTED 8 191a SHEET 3 BF -3 ELECTRONIC CONTROL MARINE SEARCI'ILIGI'IT BACKGROUND OF INVENTION SUMMARY OF INVENTION The invention provides apparatus for positioning a remote member, such as a searchlight, in a position corresponding to the position of a control member or control handle accessible to the operator. Both the remote member or searchlight and the control member are supported for movement about first and second, or horizontal and vertical, axes. A horizontal position sensing potentiometer and a vertical position sensing potentiometer are connected to the control member and sense a change in angular position of the control member relative to the first and second axes caused by manipulation of the control member by the operator.

The invention provides a searchlight assembly which includes reversible horizontal and vertical position motors which are connected to a searchlight head to position the searchlight head in a position corresponding to the selected position of a remote control member in a control assembly.

The horizontal and vertical position electric motors are respectively coupled to horizontal and vertical electrical control circuits. The horizontal and vertical control circuits are respectively connected to the horizontal and vertical position sensing potentiometers in the control assembly. Each control circuit includes a resistance bridge, a transistor preamplification stage and transistor switching stage for clockwise motor rotation, and a transistor preamplification stage and switching stage for counterclockwise motor rotation, which stages control current flow at appropriate polarities to the electric motors. Each control circuit also includes horizontal and vertical feedback potentiometers which are respectively connected to the horizontal and vertical axes of the searchlight.

Upon movement of the control member relative to either the horizontal or vertical control member axes, the horizontal and vertical resistance bridges are unbalanced and an error voltage appears across the resistance bridges and is applied to the preamplifier stages, and then to the switching stages. The switchingstages provide a current flow from a battery to the appropriate electric motor to energize the motors to rotate in the appropriate direction and move the searchlight about the horizontal and/or vertical axes. When the arms of the feedback potentiometers are moved to a point at which the resistance bridges are balanced, there will be no signal supplied to the preamplifier stages or switching stages, and thus the DRAWINGS FIG. 1 is a perspective view of a searchlight and control apparatus in accordance with the invention.

FIG. 2 is an enlarged side view in fragmentary section of the control apparatus shown in FIG. 1.

FIG. 3 is an end view of the control apparatus shown in FIG. 2 with portions removed.

FIG. 4 is an enlarged fragmentary side view in partial section and with portions removed of the searchlight assembly shown in FIG.-1.

FIG. 5 is a fragmentary front end view with portions removed of the searchlight assembly shown in FIG. 4.

FIG. 6 is a schematic diagram of the electrical circuit of the invention.

DETAILED DESCRIPTION In the drawings, FIG. 1 discloses a remote assembly or searchlight assembly which is generally designated 10 and a control assembly generally designated 12. The searchlight assembly 10 includes a base or housing 14 having an interior [6 and a remote member or searchlight head 18 which contains a sealed beam lamp 20.

In accordance with the invention, means are provided for rotatably supporting the remote member or searchlight head 18 on the housing 14 for tilting or swinging movement about a first or vertical axis. As disclosed, the means includes a bracket 22 having two spaced

upstanding sidewalls

24 and 26 joined by a web 28 (FIGS. 1 and 5). The means also includes an exteriorly threaded shaft 30 (Fig. 4) which has an axial aperture 32. The shaft 30 extends through an aperture 34 in the upper wall 36 of the housing 14, and is rotatably supported therein by bearings 38 and 40. The shaft 30 is clamped to the web 28 by a nut 42 that secures the web against a shoulder 44 on the shaft 30. A gear 48 forming a part of a means for rotating the searchlight about the first axis as subsequently described in detail, is clamped against a shoulder 44 by a nut 46.

Means are also provided for supporting the searchlight head 18 for tilting movement about a second or horizontal axis which is transverse to the first axis. As disclosed, the means is in the form of a pin or bolt 50 (FIG. 5) which extends through

apertures

52 and 54 in

side walls

24 and 26 and through apertures S6 and 58 in depending

spaced legs

60 and 62 of the searchlight head I8, which legs are located inwardly of the

sidewalls

24 and 26.

The invention also provides means for rotating the searchlight head 18 in a horizontal plane about the first axis or vertical axis. As disclosed, the means includes an electric motor 64 (FIG. 4) which has an output shaft 65 connected to a gear 66 which meshes with an idler gear 68 fixedly connected to an intermediate shaft 70 which is rotatably supported by a bracket 72. The intennediate shaft 70 is secured to a gear 74 which meshes with the gear 48 to thus provide power transfer from the motor 64 to the shaft 30. The shaft 70 is also fixedly connected to the armature of a potentiometer 152, the operation of which is hereinafter described.

Means are also provided for tilting the remote member or searchlight head 18 about the second axis. As disclosed, the means includes a second motor 76 (FIGS. 4 and 5) which has an output shaft 78 connected to a drive wheel 80 by a gear train (not shown). The means also includes a link 82 which extends through the axial aperture 32 and is reciprocal in generally coaxial relation to said first axis and is connected at one end to the drive wheel 80 by a bent or out-turned portion 82 which extends into an eccentric aperture 84 in the drive wheel 80. The other end of the link 82 is provided with an enlarged head 84 which is retained in a slot 88 in a bracket 86 which is connected to the searchlight head 18 (FIG. 4).

The position of the searchlight head I8 is selectively adjusted by the control assembly 12 which includes a control member 90 having a handle 92 mounted on a shaft or post 94 (FIGS. 2 and 3). In accordance with the invention, means are provided for supporting the control member 90 for movement about a first or vertical axis and a second or horizontal axis. As disclosed, the means includes a bracket 96 (FIG. 3) which has a bracket portion 98 connected to the post 94 and a bracket portion 100 which is at a right-angle to the portion 98 and which is fixedly connected to the shaft 102 of a first potentiometer 104. The potentiometer 104 forms part of the means for sensing a change in angular position of the control member relative to the first axis as hereinafter described.

This means also includes a mounting member 106 (FIGS. 2 and 3) which has an aperture 108 which is nonrotatably fixed on the threaded shank 110 of the potentiometer 104. The mounting member 106 is fixedly connected to the shaft 112 of a second potentiometer 114 (FIG. 2), which is supported by a U-shaped bracket 116 secured to a plate 118.

In use of the control assembly 12, tilting the control member 92 in the direction shown by arrow 103 (FlG. 2) about a horizontal axis will cause rotation of shaft 102 of potentiometer 104. Movement of control member 92 about the vertical axis as shown by arrow 105 (FIG. 3) will cause rotation of shaft 112 of potentiometer 114.

The control assembly 12 is secured to a support, a boat hull or an instrument panel 120 by a U-shaped clamp bracket 122 (FIG. 3) which has

legs

124 and 126. The bracket 122 is secured to the U-shaped bracket 116 by a bolt 128 which extends through an aperture 129 in the bracket 122, and an aperture 131 in the bracket 116. A locknut 133 secures the bolt 128 to the bracket 116. A nut 130 on the bolt 128 clamps the plate 118 against the upper or outer surface of the control panel 120 and clamps the

legs

124 and 126 against the undersurface of the control panel 120.

The plate 118 is provided with an aperture 132 to permit movement of the control member 90 and post 94 about the first and second axes.

To prevent dirt and water from entering the aperture 132, the control assembly 12 can also include a semispherical shield 134 secured to the post 94 and located beneath the plate 118. The control assembly 12 is also provided with an on-ofi" switch 136 which is electrically connected as hereinafter described.

in accordance with the invention, means are provided for sensing a change in the angular position of the control member 90 relative to the first or vertical axis of the control member 90. Said means is electrically connected to the means for moving the searchlight head about the first axis of the searchlight to a position corresponding to the angular position of the control member relative to the first axis of the control member. As disclosed, the means includes the potentiometer 114 which is part of a circuit 138 which is connected to the motor 64 and to a battery 150, a resistance bridge 140 (FIG. 6), first and

second preamplifier stages

142 and 144, and first and second transistor switching stages 146 and 148.

Movement of the control handle 92 about the first axis or vertical axis causes a movement of the arm of the potentiometer 114 which unbalances the resistance bridge 140. This produces a small voltage which is applied to either the first or second preamplifier stages depending on the direction of rotation of the control member. A counterclockwise rotation of the control member 90 will supply a voltage or current to the preamplifier stage 144 which supplies a current to the switching transistor stage 148 which thus causes a current flow to the motor 64. The motor 64 will remain energized until the arm of a potentiometer 152 is moved to a position balancing the resistance bridge 140. When the bridge 140 is balanced, no current flows to the preamplifier or switching stage 148 and the motor 64 is deenergized, interrupting movement of the remote member or Searchlight head 18 at an angular position relative to the first or vertical axis corresponding to the angular position of the control member 90 relative to the vertical or first axis.

More specifically, the potentiometer 114 has one end of its resistance element 154 connected by a lead 158 to a resistor 156 (FIG. 6). The other terminal of the resistance element 154 is connected by a lead 160 to a resistor 162. The resistors 156 and 162 form the resistance bridge 140. The other terminal of the resistor 156 is connected by a lead 166 to the base 186 of a transistor 188. The other terminal of resistor 162 is connected by a lead 168 to the base 191 oftransistor 196.

The arm of potentiometer 114 is connected by a lead 172 to one terminal of a resistor 174. The other terminal of the resistor 174 is connected by a lead 176 to one terminal of the on-off switch 136. The other terminal of the on-off switch 136 is connected by a lead 178 to the positive terminal of battery 150. The resistor 174 is also connected by a lead 182 to the cathode of a diode 180. The anode of the diode 180 is connected by a lead 184 to ground 200.

The voltage generated by unbalancing the resistance bridge caused by movement of the potentiometer arm 170 of potentiometer 114 in a clockwise direction will supply a voltage to the base 186 of transistor 188 in the first preamplification stage. The emitter 190 of transistor 188 is connected by a lead 192 to the emitter 194 of a transistor 196 of the clockwise preamplification stage.

An adjustment potentiometer 198 can be provided and be connected between the emitter 190 and ground 200. The negative terminal of the battery 150 is also connected to ground 200.

The collector 202 of transistor 188 is connected by a lead 204 to the base 206 of a second preamplifier transistor 208 in the counterclockwise transistor stage. The collector 202 of transistor 188 is coupled to lead 176 through a resistor 209. The emitter 210 of the transistor 208 is connected to the base 212 of a switching transistor 214 by a resistor 216 and a lead 218. The emitter 220 of transistor 214 is connected to ground by a lead 222. The collector 224 is connected by a lead 226 to the motor 64 through a resistor 228.

The collector 230 of transistor 208 is connected by a lead 232 to the base 234 of a second switching transistor 236. A resistor 238 is coupled in the lead 232. The collector 240 of the transistor 236 is connected by a lead 242 to the other terminal of the motor 64. The emitter 244 of transistor 236 is connected by a lead 237 to a lead 176 which is connected to the positive terminal of the battery 150.

When the control member is rotated in the clockwise direction, an error voltage is supplied to the preamplifier transistor 196 and the amplified signal is applied to a second preamplifier transistor 246 by a lead 248 which is connected to the base 250 of the transistor 246. The emitter 252 is connected to the base 254 of a switching transistor 256 by a resistor 258. The base 250 of transistor 246 is also connected to lead 176 by a resistor 263. The emitter 262 of transistor 256 is connected to ground 200. The collector 266 is connected by a lead 268 to one terminal of the motor 64. The collector 270 of transistor 246 is connected to the base 272 of a switching transistor 274 by a lead 276 and a resistor 278. The collector 280 of transistor 274 is connected to the other terminal of motor 64 by a lead 282.

The means provided to sense a change in angular position of the control member relative to the second or horizontal axis includes the potentiometer 104, a circuit 338 which includes a resistance bridge 340, first and second preamplifier stages 342 and 344, and first and second

transistor switching stages

346 and 348. The circuit 338 includes identical components and has the same operation as the stages in circuit 138, described above.

Movement of the control handle 92 about the horizontal axis causes movement of the arm 316 of the potentiometer 104 to thus unbalance the resistance bridge 340. This produces a small voltage which is applied at either the first or second preamplifier stages depending upon the direction of rotation of the control handle 92. A forward movement of the control member 90 will supply a voltage or current to the preamplifier 344 which is amplified and applied to the switching transistor stage 348 which provides a current path to the electric motor 76 which remains energized until the arm of a potentiometer 352 is moved to a position balancing the bridge 340 and causing current flow to the preamplifier stage and switching

stages

346 and 348 to cease, and thus deenergize the motor 76 and stop movement of the searchlight head 18 at an angular position relative to the horizontal axis corresponding to the angular position of the control member relative to the control member horizontal axis.

More specifically, the control circuit which senses the position of the control member relative to the horizontal control member axis includes a lead 358 which connects the potentiometer 104 to a resistor 356. The other terminal of the resistance element of the potentiometer is connected by a lead 360 to a resistor 362. The other terminal of the resistor 356 is connected by a lead 366 to the base 386 of a transistor 388. The other terminal of resistor 362 is connected by a lead 368 to the base 391 of a transistor 396. The arm 370 of potentiometer 104 is connected by a lead 372 to one terminal of a resistor 374. The other terminal of the resistor 374 is connected by a lead 376 to one terminal of the on-off switch 136. The other terminal of resistor 374 is connected by a lead 382 to the cathode of the diode 380. The anode of the diode 380 is connected by a lead 384 to ground 200.

The voltage generated by unbalancing the resistance bridge caused by movement of the potentiometer arm 370 in a forward direction will supply a voltage to the base 386 of transistor 388 in the first prearnplification stage. The emitter 380 is connected by 'a lead 392 to the emitter 394 of a transistor 396 of the forward preamplification stage. An adjustment potentiometer 398 can also be provided between the emitter 380 and ground 200. The collector 402 of transistor 388 is connected by lead 404 to the base 406 of a second preamplifier transistor 408 in the rearward transistor stage. The transistor 388 is coupled to the lead 376 by a resistor 409. The emitter 401 of the transistor 408 is connected to the base 412 of a switching transistor 414 through a resistor 416 by a lead 418.

The emitter 420 of transistor 414 is connected to ground by a lead 422. The collector 424 is connected by a lead 426 to the motor 76 through a resistor 428. The collector 430 of transistor 408 is connected by a lead 432 through a resistor 438 to the base 434 of a second switching transistor 436. The collector 440 of transistor 446 is connected by a lead 442 to the other terminal of motor 76. The emitter 444 of transistor 436 is connected to the lead 376 by a lead 437.

When the control member is tilted rearwardly about its horizontal axis a voltage is supplied to the preamplifier transistor 396 which applies a signal or a voltage pulse to a second preamplifier transistor 446 by a lead 448 which is connected to the base 450 of transistor 446. The collector of transistor 396 is coupled to a lead 376 by a resistor 449. The emitter 452 is connected to the base 454 of a switching transistor 456 by a resistor 458 and a lead 460. The emitter 462 of transistor 456 is connected to ground 200. The collector 466 is.connected by a lead 468 to one terminal of the motor 76. The collector 470 of transistor 446 is connected to the base 472 of a switching transistor 474 by a lead 476 and a resistor 478. The collector 480 of transistor 474 is connected to the other terminal of motor 76 by a lead 482.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

l. Searchlight apparatus comprising a searchlight head, a first support, means for supporting said searchlight head on said first support for movement about first and second axes, means for moving said searchlight head about said first and second axes, respective first and second potentiometers responsive to movement of said head about said first and second axes, a control member, a second support, means for supporting said control member on said second support for movement about first and second axes respectively parallel to said first and second searchlight head axes, means including third and fourth potentiometers connected to said control member for sensing a change in angular position of said control member relative to said first and second axes of said control member, a power source, and an electrical circuit connected to said power source, to said first, second, third, and fourth potentiometers, and to said means for moving said searchlight head about said first and second searchlight head axes, said electrical circuit including first and second resistance bridges respectively connected to said first and third potentiometers and to said second and fourth potentiometers, and first and second semiconductor switching means respectively connected to said first and second resistance bridges and respectively operable in response to imbalances in said resistance bridges for energizing said means for moving said searchlight head about said first and second searchlight head axes to affect a change in position of said searchlight with respect to said searchlight head axes corresponding to the position of said control member with respect to said control member axes.

2. Apparatus in accordance with claim 1 wherein said means for supporting said searchlight head for movement about first and second axes comprises a bracket, a shaft fixedly connected to said bracket and rotatably supported in said first support to afford rotation of said bracket relative to said first support about a vertical axis, and means for pivotally connecting said searchlight head to said bracket to afford tilting movement of said searchlight head relative to said bracket about a horizontal axis.

3. Searchlight apparatus comprising a searchlight head, a housing, a bracket, a shaft fixedly connected to said bracket and rotatably supported in said housing to afford rotation of said bracket relative to said housing about a vertical axis, and means for pivotally connecting said searchlight head to said bracket to afford tilting movement of said searchlight head relative to said bracket about a horizontal axis, an axial aperture in said shaft, a first electric motor, a drive wheel gearing connecting said electric motor to said drive wheel, a rod eccentrically connected to said drive wheel, said rod extending through said axial aperture in said shaft and engaged with said searchlight head at a point spaced from said horizontal axis to afford movement of said searchlight head about said horizontal axis in response to movement of said rod axially of said shaft, a second electric motor, and means connecting said second electric motor to said shaft to rotate said shaft and said bracket about a vertical axis, a control member, a support, means for supporting said control member on said support for movement about first and second axes, means connected to said control member for sensing a change in angular position of said control member relative to said first and second axes of said control member, a power source, and an electrical circuit connected to said power source, to said position sensing means connected to said control member, and to said first and second electric motors, said electrical circuit including semiconductor switching means for energizing said first and second electric motors to affect a change in position of said searchlight with respect to said searchlight axes corresponding to the position of said control member with respect to said control member axes.

4. Apparatus in accordance with claim 3 wherein said electrical circuit includes first and second preamplifier stages and first and second transistor switching stages for said first electric motor, and first and second preamplifier stages and first and second transistor switching stages for said second electric motor.

5. Searchlight apparatus comprising a searchlight head, a first support, means for supporting said searchlight head on said first support for movement about first and second axes, means for moving said searchlight head about said first and second axes, a control member, a second support, means for supporting said control member on said second support for movement about first and second axes and for sensing a change in angular position of said control member relative to said control member first and second axes including a horizontal position sensing potentiometer having a vertically extending shaft, a vertical position sensing potentiometer having a horizontally extending shaft, a bracket fixedly connecting said control member to said shaft of said vertical position sensing potentiometer, a mounting member fixedly connecting said shaft of said horizontal position sensing potentiometer to said vertical position sensing potentiometer, and means adapted for mounting said horizontal position sensing potentiometer on said second support, a power source, and an electrical circuit connected to said power source, to said horizontal and vertical position sensing potentiometers, and to said means for moving said searchlight about said first and second searchlight head axes, said electrical circuit including semiconductor switching means for energizing said means for moving said searchlight head about said first and second searchlight axes to affect a change in position of said searchlight with respect to said searchlight axes corresponding to the position of said control member with respect to said control member axes.

6. Searchlight apparatus comprising a searchlight head, means for supporting said searchlight head for movement about first and second axes, means for moving said searchlight head about said first and second axes, a control member, means for supporting said control member for movement about first and second axes, position sensing means connected to said control member for sensing a change in angular position of said control member relative to said first and second axes of said control member, a power source, and an electrical circuit connected to said power source, to said position sensing means connected to said control member, and to said means for moving said searchlight head about said first and second searchlight head axes, said electrical circuit including a horizontal position control stage and a vertical position control stage, each of said horizontal and vertical position control stages including a resistance bridge and a feedback potentiometer, said resistance bridges being connected to clockwise and; counterclockwise preamplification and switching stages, and to said feedback otentiometers, said switching stages being operative to energize said means for moving said searchlight head upon movement of said control member, said feedback potentiometers being operative to balance said resistance bridges when said searchlight head is moved to a position corresponding to the position of said control member to thereby deenergize said means for moving said searchlight about said first and second axes.

7. A remote member, means for supporting said remote member for movement about first and second axes, means for moving said remote member about said first and second axes, a control member, means for supporting said control member for movement about first and second axes, a power source, an electrical circuit connected to said power source, and to said means for moving said remote member about said first and second remote member axes, said electrical circuit including first and second potentiometers having shafts connected to the control member with said shafts providing said first and second axes of said control member, and semiconductor switching means connected to said potentiometers and connected to said means for moving said remote member about said first and second remote member axes to energize said means for moving said remote member to affect a change in position of said remote member with respect to said remote member axes corresponding to the position of said control member with respect to said control member axes.

8. Searchlight apparatus comprising a searchlight head, a first support, means for supporting said searchlight head on said first support for movement about first and second axes,

means for moving said searchlight head about said first and second axes, a control member, a second support, means for supporting said control member on said second support for movement about first and second axes respectively parallel to said first and second searchlight head axes, a power source, and an electrical circuit connected to said power source and to said means for moving said searchlight head about said first and second searchlight head axes, said electrical circuit including a resistance bridge comprising a first potentiometer responsive to searchlight head movement about said first searchlight head axes, and a second potentiometer responsive to control member movement about said first control member axis, and switching means operable in response to imbalance in said resistance bridge for energizing said means for moving said searchlight head about said first searchlight head axis to affect a change in position of said searchlight with respect to said first searchlight head axis corresponding to the position of said control member with respect to said first control member axis.

553 I UNITED STATES PATENT OFFICE CERTIFICATE OF' CORRECTION Pate t 3,631,328 1 v Dated December 28 1971 Inventor(s) Gaylord M Borst and Robert A. Booty It is certified that error appears in theabove identified patent I and that said Letters Patent are hereby corrected as shown below:

Abstract of Discl osure, line 1 "in" should be is Column line 18 "401" should be .410-

Cclumn 6, Time 1.7 I after "wheel" insert a comma Signed and seale'd this mm day of July 1972.

(SEAL) Attest;

ROBERT GOITSCHALK Commissioner of Patents EDWARD M.FLEI'CHER, JR. Attesting Officer mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 34631328 Dated December 28 1971 Inventor(s) Gaylord M. Borst and Robert A. Booty It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Abstract of Discl osure, line 1 "in" should be is column 5, line 18 "401" should be "-410 Cclumn 6, iine 17 after "Wheel" insert a comma Signed and sealed this Luzh day of July 1972.

(SEAL) Attest:

EDWARD PLFLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Cozrmulssioner' of Patents

Claims

1. Searchlight apparatus comprising a searchlight head, a first support, means for supporting said searchlight head on said first support for movement about first and second axes, means for moving said searchlight head about said first and second axes, respective first and second potentiometers responsive to movement of said head about said first and second axes, a control member, a second support, means for supporting said control member on said second support for movement about first and second axes respectively parallel to said first and second searchlight head axes, means including third and fourth potentiometers connected to said control member for sensing a change in angular position of said control member relative to said first and second axes of said control member, a power source, and an electrical circuit connected to said power source, to said first, second, third, and fourth potentiometers, and to said means for moving said searchlight head about said first and second searchlight head axes, said electrical circuit including first and second resistance bridges respectively connected to said first and third potentiometers and to said second and fourth potentiometers, and first and second semiconductor switching means respectively connected to said first and second resistance bridges and respectively operable in response to imbalances in said resistance bridges for energizing said means for moving said searchlight head about said first and second searchlight head axes to affect a change in position of said searchlight with respect to said searchlight head axes corresponding to the position of said control member with respect to said control member axes.

6. Searchlight apparatus comprising a searchlight head, means for supporting said searchlight head for movement about first and second axes, means for moving said searchlight head about said first and second axes, a control member, means for supporting said control member for movement about first and second axes, position sensing means connected to said control member for sensing a change in angular position of said control member relative to said first and second axes of said control member, a power source, and an electrical circuit connected to said power source, to said position sensing means connected to said control member, and to said means for moving said searchlight head about said first and second searchlight head axes, said electrical circuit including a horizontal position control stage and a vertical position control stage, each of said horizontal and vertical position control stages including a resistance bridge and a feedback potentiometer, said resistance bridges being connected to clockwise and counterclockwise preamplification and switching stages, and to said feedback potentiometers, said switching stages being operative to energize said means for moving said searchlight head upon movement of said control member, said feedback potentiometers being operative to balance said resistance bridges when said searchlight head is moved to a position corresponding to the position of said control member to thereby deenergize said means for moving said searchlight about said first and second axes.

8. Searchlight apparatus comprising a searchlight head, a first support, means for supporting said searchlight head on said first support for movement about first and second axes, means for moving said searchlight head about said first and second axes, a control member, a second support, means for supporting said control member on said second support for movement about first and second axes respectively parallel to said first and second searchlight head axes, a power source, and an electrical circuit connected to said power source and to said means for moving said searchlight head about said first and second searchlight head axes, said electrical circuit including a resistance bridge comprising a first potentiometer responsive to searchlight head movement about said first searchlight head axes, and a second potentiometer responsive to control member movement about said first control member axis, and switching means operable in response to imbalance in said resistance bridge for energizing said means for moving said searchlight head about said first searchlight head axis to affect a change in position of said searchlight with respect to said first searchlight head axis corresponding to the position of said control member with respect to said first control member axis.