US3892920A

US3892920A - Acoustic activated switch

Info

Publication number: US3892920A
Application number: US476439A
Authority: US
Inventors: Eric A Kolm
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-06-05
Filing date: 1974-06-05
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01

Abstract

An acoustic switch including two tuned transducers, a bistable switch coupled to one of the transducers and a monostable switch coupled to the other transducer is responsive to acoustic signals in a predetermined frequency range to control the two functions of an auxiliary device coupled to the switch. In one embodiment, the auxiliary device is a television receiver and the functions controlled are the electrical power to the receiver and the channel selection.

Description

United States Patent l 1 1 I i i I 3,892,920 Kolm l l July 1, 1975 ACOUSTIC ACTIVATED SWITCH 3.713. a 1/1973 Boyd et ill r l78/DIU. I5 20. 3 l973 F fl 343 225 I76] Inventor: Eric A. Kolm, 37 Evans Rd 3 7 8| mwn e [Cr Brookline, Mass. O2l46 Primary Examiner-Kathleen H. Clafiy l22l Fledi June I974 Assistun! E.\'uminerTommy P. Chin [2H Appll NO; 476.439 Attorney, Agenl. 0r FirmAmster & Rothstein [52] US. Cl .7 179/1 VC; l78/DIG. 15; 325/392; ABSTRACT n acoustic switc me u in two tune trans ucers, u 51 I Cl EMU/MiI 3443/225 A r l l g d d l 'l 0 b bistable switch coupled to one of the transducers and [5 l 0 care a monostable switch coupled to the other transducer is 340/148 325/392 343/225 responsive to acoustic signals in a predetermined frequency range to control the two functions of an auxili- [56] Reierences Cmed ury device coupled to the switch. In one embodiment. UNITED STATES PATENTS the auxiliary device is a television receiver and the 3.101644 9/1963 Hooper n l78/DIG. l5 functions controlled are the electrical power to the re- 3.112. 8 ll/l963 Adl r 340/148 ceiver and the channel selection. 3,537,012 lU/l970 Reichard et all .t 325/392 3.678392 7/1972 Houghton 325/392 7 Claims, 8 Drawing Figures 1k :7 ("I p c R! R)! R7 ACOUSTIC ACTIVATED SWITCH The invention relates to acoustic control devices and particularly acoustic switches for remotely controlling the function of an auxiliary device coupled to the control device.

There are many remote control devices which have been devised to respond to signals transmitted from remote locations for control of auxiliary devices. These devices can be arranged to respond to signals in various frequency ranges and in the past have been relatively complex. An improvement in these prior devices is disclosed in copending application Ser. No. 281 ,420, filed on Aug. 17, 1972 by Eric Kolm now abandoned. This improved device is arranged to be responsive to acoustic signals in the audible and super audible frequency range and in response to these signals to control a function of an auxiliary electrical device. A specific application for this switch for remotely controlling the tuner in a television receiver to control the channel selection function of a television receiver is disclosed in U.S. patent application Ser. No. 359,315 filed on May ll, 1973 by Eric Kolm now abandoned. These applications, Ser. NOs. 281,420 and 359,315, referenced above, are expressly incorporated by reference herein.

The devices disclosed in the above referenced patent applications work quite satisfactorily. however, there are possibilities for improving their operation. For example, the remote control devices described above can readily control only one function of the auxiliary device. Thus, the remote control device can either control the electrical power to an electrical device, or control another function, such as the channel selection function of a television receiver, (application Ser. No 359,315) but not both. Thus in the disclosed television receiver, the power to the receiver is controlled by a mechanical switch arranged to operate at only one po sition of the tuner.

In general, it is an object of the present invention to provide an acoustic remote control device which improves upon the performance of such devices which were available in the past. Specifically, it is an object of the invention to provide an improved acoustic remote control device which can readily control more than one function of an auxiliary device coupled thereto.

It is a particular object of the invention to provide an acoustic remote control device for a television receiver which can control both the channel changing function of the receiver and the flow of electrical power to the receiver independently of the position of the tuner in the television receiver. It is a still further object of the invention to provide such a remote control device which can be used with existing television receivers.

It is another object of the invention to provide such an acoustic remote control device which is relatively simple to construct and is relatively low in cost.

In accordance with the invention, the improved acoustic switch adapted to control an auxiliary device includes first and second acoustic transducers which are tuned to respond to acoustic signals in a predetermined frequency range and to convert the acoustic signals to electrical signals. A bistable switch coupled to the first tuned transducer and having output means adapted to be coupled to the auxiliary device is switched between a first and second stable state in response to acoustic signals detected by the first transducer for controlling a function of the auxiliary device. A monostable switch coupled to the second tuned transducer and having output means adapted to be coupled to the auxiliary device is switched between a stable and an unstable state in response to acoustic signals detected by the second tuned transducer to control another function of the auxiliary device when the monostable switch is switched to its unstable state.

To describe the operation of an illustrative embodiment of the acoustic remote control switch of this invention, it is assumed that the switch is in a quiescent condition. The bistable switch is in a first stable state wherein it activates the first tuned transducer to acoustic signals and deactivates the second tuned transducer. In this condition, the monostable switch is in its stable state. A remotely generated acoustic signal is detected by the first tuned transducer which converts the acoustic signal to an electrical signal. The bistable switch responds to the electrical signal and switches into its second stable state which activates the second tuned transducer, deactivates the first tuned transducer and controls one function of the auxiliary device. In this condition, the next received acoustic signal is detected by the second tuned transducer. The monostable switch responds to the detected acoustic signal and is switched to its unstable state for a predetermined period of time to control a function of the auxiliary device and during which the first tuned transducer is activated. If another acoustic signal is not received during this predetermined time interval, the monostable switch returns to its stable state wherein the first tuned transducer is again deactivated. To return the bistable switch to its first stable state, an acoustic signal is transmitted while the monostable switch is in the unstable state. As explained above, with the monostable switch in the unsta' ble state, the first tuned transducer is activated and an acoustic signal transmitted during this time interval will be detected by the first tuned transducer and the bistable switch, in response to the signal, will be switched to its first stable state.

In one specific application for this acoustic switch, the bistable switch is arranged to control the flow of electrical power to a television receiver and the monostable switch is arranged to control the channel selection function of the receiver.

The above brief description, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of the presently preferred but nonetheless illustrative embodiments of the present invention when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram representation of the acoustic switch of this invention arranged to provide electrical power to an auxiliary device and to control another function of an auxiliary device;

FIG. 2 is a partial front elevational view of a television receiver modified to include the acoustic switch arranged for providing remote channel selection control and electrical power control and showing an acoustic transmitter for transmitting a control signal;

FIG. 3 is a top plan view partially broken away showing the arrangement of the elements of the acoustic switch;

FIG. 4 is an exploded side elevational view partially broken away and partially in section of a tuner drive assembly for driving the tuner in the television receiver in response to acoustic signals;

FIG. 5 is a vertical sectional view of the tuner drive assembly, assembled and mounted on the shaft of the tuner in the television receiver;

FIG. 6 is a front elevational view of the assembled tuner drive assembly showing the front dial plate;

FIG. 7 is a view taken along the lines 77 of FIG. 5 and showing a unidirectional clutch in the tuner drive assembly arranged for rotation of the tuner shaft; and

FIG. 8 is a view similar to that shown in FIG. 7 but showing a ratchet and pawl assembly for rotation of the tuner shaft.

Referring to FIG. 1, there is shown the acoustic switch of this invention which is arranged to control two functions of an auxiliary device, not shown, which can be coupled to the switch as described below. In general, the switch includes two tuned transducers, designated M1 and M2, which respond to acoustic signals in a predetermined frequency range and which convert the acoustic signals to electrical signals. A bistable switch including dual operational amplifiers lClA and IC] B is part of an integrated circuit chip, generally designated as lCl which receives power from a power source, not shown, through plug PL], diode CR1, resistor R1, capacitor C1 and Zenor diodes CR9, CR10. The bistable switch also includes transistors 03 and 04 arranged in a Darlington configuration to drive relay Kl. The movable contact of relay K1 is coupled to a source of electrical power through plug PL and the stationary contact 2 is coupled to outlet 50. A monostable switch includes dual operational amplifiers lC2A, IC2B which is part of integrated circuit chip lC2 which receives power from the power source, through plug PL in a manner to be described below. The monostable switch includes transistors 01, Q2 arranged in a Darlington configuration to drive relay K2 which activates solenoid SOL to control a second function of the auxiliary device.

To understand the overall operation of the acoustic switch, it is assumed that the switch is in a quiescent state in which power is applied to one terminal of tuned transducer Ml through a power supply plug PL, contact 1 of relay Kl, diode CR4 and resistor R13, to sensitize transducer Ml. In this state the bistable switch is in its first stable state, with relay Kl deactivated as shown. Since no electrical power is applied to trans ducer M2, this transducer is deactivated and the monostable switch is in its stable state with relay K2 deactivated as shown.

When an acoustic signal in a predetermined frequency range is detected by transducer M1, the transducer converts the signal into an ac. electrical signal. This electrical signal is coupled across input pins 8, 9 of lClA, the first of the dual operational amplifiers and since the signal is relatively high is power and the transducer has a high impedence, no transformer is required. Resistors R18, R8, R25, and R7 are arranged as a voltage divider to control the gain of lClA. The amplified electrical signal appears at pin 12 and is coupled through RC filter C12, R4, to one input pin 5, of the second operational amplifier lClB. As is known in the art, a change in the relative potentials between pins 5 and 6 of an operational amplifier will cause a change in the output potential of the operational amplifier, pin 2. As shown in FIG. 1, lClB is arranged with a feedback loop so that the output from pin 2 is fed back to the input terminal, pin 6 through resistors R11, R15, R5 and resistive capacitive network R20, C5. This latter network controls the length of time required to change the relative potential ditference between pins 5 and 6 and is explained in greater detail in application Ser. No. 281,420 referenced above.

Upon receiving an electrical signal on pin 5, the output potential at pin 2 changes to a potential which is applied to transistors 03, O4 to activate relay K]. The movable contact of relay Kl, moves into contact with stationary contact 2 with the following results: l electrical power is coupled to outlet SO from plug PL to provide power to an auxiliary device and to Lamp L1; (2) power is removed from transducer Ml thereby deactivating that transducer; and (3) electrical power is applied to transducer M2 and the monostable switch through a circuit including resistors R23, diode CR2, lamp L3, Zenor diodes CR1], CR12 and capacitor C2.

When the next acoustic signal in the proper frequency range is transmitted, it is detected by activated transducer M2. Transducer M2 converts this signal into an a.c. electrical signal which is applied to operational amplifier ICZA arranged similarly to operational amplifier lClA. The amplifier electrical output signal from ICZA is coupled to pin 5 at the second operational amplifier IC2B to produce a change in the output of lC2B, which appears at pin 2, in a manner similar to that described with reference to operational amplifier lC 1B. This change in potential at pin 2 activates relay K2 through transistors 01, Q2 which moves the movable contact of relay K2 to position 2. In this position, potential is applied through diode bridge CRS-CRS to SOL to activate the SOL to provide control of a function of an auxiliary device. With the arm of relay K2 in position 2, transducer M1 is activated from the power source through plug PL and relay contacts of K2, diode CR3 and resistor R14.

This is the unstable state of the monostable switch, and the monostable switch is arranged to switch back to the stable state within a predetermined time interval. This monostable operation is provided by applying electrical power through the movable contact relay K2, lamp L2 and resistor R2] to terminal 6 of lCZB. When relay K2 is activated the potential to neon lamp L2 and R21 in this condition will cause L2 to conduct after a predetermined interval of time. When L2 conducts, the relative potentials between terminals 5 and 6 of [C28 change causing a change in the potential at pin 2 which deactivates relay K2; the movable contact of relay K2 returning to position 1. However, if another acoustic signal is received while the monostable switch is in the unstable state, transducer M], which is activated as explained above, will detect the signal. The ac. electrical signal will change the relative potentials between pins 5 and 6 of lClB causing deactivation of relay K1 and removing power from the auxiliary device.

To briefly summarize the operation of the circuit, a first received acoustic signal causes activation of relay K1 and electrical power is coupled to an auxiliary device. Reception of a second acoustic signal controls a function of the auxiliary device by activation of relay K2 in the monostable switch for a predetermined period of time. If another acoustic signal is received while relay K2 is activated, relay K1 is deactivated and power is removed from the auxiliary device. Greater detail concerning the operation of the acoustic switch may be had by reference to US. patent application Ser. No. 281,420, referenced above.

As a specific application for the acoustic switch described above, the switch is arranged to control a television receiver. In particular, the switch is arranged to control both power to the receiver and the channel selection function of the receiver.

In general, television receivers are provided with a tuner which is rotated to tune in the various television channels broadcast by television stations. The tuner is mounted in the receiver and has the shaft which extends forwardly toward the front of the receiverv Coupled to the front end of the tuner shaft is a knob and indicator. To change television channels, the knob is rotated to apply a torque to the tuner shaft which is of sufficient magnitude to overcome the torque resistance of the tuner. Most tuners today are arranged with a detent mechanism so that when the tuner shaft is rotated a predetermined number of degrees, the shaft will continue to rotate even if no further force is applied to the tuning knob. In accordance with this invention, the television receiver is modified to include an acoustic control switch for changing the channels and controlling the flow of electrical power to the television receiver to turn the receiver on and ofF. By utilizing the acoustic switching circuit described above, the receiver can be turned on and offirrespective of the position of the tuner shaft.

Referring now to FIG. 2, there is shown a partial front view of a television receiver, designated generally by reference numeral 10, modified with an acoustic remote control device generally designated by reference numeral 12 and including tuner drive assembly 14 and acoustic switch 16. As shown, a power cable 18 from the television receiver is coupled to the rear of the acoustic switch 16 and is connected to outlet SO (FIG. 1). The acoustic switch has a power cable 20 which is adapted to be coupled to a source of electrical power such as a wall outlet. Coupled between acoustic switch 16 and tuner drive assembly 14 is flexible cable 22, the function of which will be described in detail below. The drive assembly also includes an adjustable support 23 to aid in supporting the mechanism on a television receiver. Also shown in FIG. 2 is an acoustic transmitter 24, for producing acoustic signals in a predetermined range of frequencies.

Referring now to FIG. 2, there is shown a simplified diagrammatic representation of the arrangement of the elements of the acoustic switch 16 shown in detail in FIG. 1. As shown, the circuit includes the two tuned transducers M1, M2 mounted on terminal board along with the other electrical components, relays K1, K2 and solenoid SOL, arranged with its armature coupled to the inner cable 32 of cable 22.

FIGS. 3 and 4 show in detail the drive assembly for changing channels in the television receiver. A television tuner, partially shown and designated by reference numeral 34, is mounted in the receiver which has a front plate, partially shown, and designated by reference numeral 36. Extending forwardly from the tuner is a shaft 38 which is rotatably mounted with respect to the tuner and is rotated for changing the television channels. Rotatably mounted with respect to shaft 38, is a concentric shaft 40, coupled to the fine tuning circuits in tuner 34. A fine tuning knob 42 is mounted on the fine tuning shaft to provide fine tuning capability for the receiver, as is well known. To this point, there has been described a conventional arrangement for tuners in television receivers. The conventional receiver has a dial, such as shown in FIG. 5, positioned on the forward end of shaft 38 and the television set is tuned by rotation of the knob which in turn rotates shaft 38.

In accordance with a feature of the invention, a tuner drive mechanism is interposed between shaft 38 and the dial, for remote control of the channel changing function of the receiver under the control 1 of the acoustic switch. The tuner drive assembly includes a hollow cylindrical housing 44, having mounted therein a torque-producing element, generally designated as reference numeral 46. The torque-producing element is mounted on shaft 48 which extends rearwardly through a hole in the rear wall of housing 44. Mounted on the rearward end of shaft 48 is a larger diameter shaft 50 having a central bore 52 adapted to engage the forward end of shaft 38 at key 39. Shaft 48 also extends forwardly of torque producing-element 46 through a hole in the forward wall of housing 44 and has spacers 52 and 54 mounted thereon. The forward end of shaft 48 is cut away forming a key 56 similar to key 39 on shaft 38. A dial (shown in front view in FIG. 5) including a front plate 58, a transparent window 60, a turning bar 62 and rear plate 64 on which is imprinted the channel numbers is mounted on the forward end of shaft 48. The inner plate is rotatably mounted with respect to the outer plate so that after the dial is placed on the television receiver, the inner plate can be aligned with an indicator on the receiver to show the channel to which the receiver is tuned. Thereafter, as the tuner is rotated, the correct channel will be indicated automatically.

Referring to FIG. 7, there is shown one embodiment of torque-producing element 46 in the form of a unidirectional clutch 66. The clutch is mounted on shaft 48 and has one end of cable 32 coupled to its outer leg at 69. The other end of cable 32 is attached to the movable arm of solenoid SOL as explained above. Coiled spring 68 wound around the outer rearward surface of clutch 66 has one end secured to clutch 66 at point 70 and the other end secured to housing 44 at point 72 to urge clutch 66 to rotate in a clockwise direction. It can now be seen that when solenoid SOL is activated, a torque is applied to the clutch by cable 32 which pulls the end of the unidirectional clutch 69 to the right producing rotation of shaft 48 and tuner shaft 38 to effect a change in the television channel. Since the distance that shaft 38 must be rotated to effect a change in channel may differ for different tuners, adjustment screw 74 is provided to set the left most position of the end of the clutch. When force is released from cable 32, spring 68 urges clutch 66 clockwise back to its original position into contact with adjustment screw 74.

FIG. 8 shows another embodiment of a torqueproducing element. In this embodiment, a ratchet member 76 is mounted on shaft 48 and paw] assembly 78 is mounted on housing 82. Adjustment screw 74 is again provided. In this embodiment, a force on cable 32 produces rotation of housing 82 causing pawl assembly 78 to drive ratchet 76 thereby rotating shaft 48 to change the channel in the receiver, as described above. A spring, not shown, but similar to spring 68 in FIG. 7, urges housing 82 clockwise after release of the force from cable 32.

Operation of the remote television receiver control will now be apparent. The tuner drive assembly is positioned in the receiver with shaft 48 engaging the tuner shaft and the cable coupled to the solenoid in the acoustic switch. The power cable from the receiver is connected with the outlet SO in the acoustic switch and the plug FL of the acoustic switch is inserted into a conventional source of ac power such as a wall outlet. Upon a first acoustic signal being transmitted from transmitter 24, relay K1 in the acoustic switch is activated and power is applied to the television receiver through outlet S to turn the receiver on. A subsequent transmitted acoustic signal activates relay K2. in the acoustic switch for a predetermined period of time during which solenoid SOL is activated. Activation of the solenoid produces a force on cable 32 which rotates drive assembly 46 to produce a torque on shaft 38 to rotate shaft 38 a sufficient distance to cause the tuner to step to the next channel. After the predetermined time interval, relay K2 is deactivated which deactivates the solenoid SOL, releasing the force on cable 32 and permitting the tuner drive assembly to freely rotate back to its starting position under the influence of spring 68. Subsequent acoustic signals produce further stepping of the tuner in the receiver. When two acoustic signals. separated in time by less than the predetermined time during which relay K1 is activated, are transmitted, relay K1 is deactivated and electrical power is removed from the television receiver.

What has been described above and illustrated in the drawings are some examples of the concepts of the present invention. These examples are not exhaustive and many modifications can be made which are within the skill of the art without departing from the spirit and scope of the invention.

What I claim is:

1. An acoustic switch responsive to acoustic and remotely generated signals in a predetermined frequency range for use in controlling at least two functions of an auxiliary device adapted to be connected to said switch comprising a first tuned transducer, a second tuned transducer. a first switch receiving input from said first transducer and adapted to be connected to said auxiliary for controlling a first function of said device, a second switch receiving input from said second transducer and operative during a conditioning interval and adapted to be connected to said auxiliary device for controlling a second function of said device, means electrically interconnecting said first and second switches and said first and second tuned transducers and arranged such that during said conditioning interval said first transducer is activated to respond to a second acoustic signal to control said first function of said device.

2. An acoustic switch responsive to acoustic and re motely generated signals in a predetermined range of frequencies for use in controlling at least two functions of an auxiliary device adapted to be connected to said switch comprising first and second tuned transducers responsive to said acoustic and remotely generated signals for converting said acoustic signals into corre sponding first and second electrical control signals, a bistable switch having a first and second stable state electrically connected to said first tuned transducer, said bistable switch being switched between said first and second stable states in response to control signals from said first tuned transducer and having output means adapted to be coupled to said auxiliary device for controlling one function of the auxiliary device, a monostable switch having a stable state and an unstable state electrically connected to said second tuned transducer, said monostable switch being switched between its stable state and its unstable state in response to control signals from said second tuned transducer and remaining in its unstable state for a predetermined time interval before returning to its stable state, said monostable switch having output means adapted to be coupled to said auxiliary device for controlling a second function of the auxiliary device when said monostable switch is in its unstable state.

3. An acoustic switch responsive to acoustic and remotely generated control signals in a predetermined range of frequencies for use in controlling at least two functions of an auxiliary device adapted to be connected to said switch comprising first and second tuned transducers responsive to said acoustic and remotely generated signals for converting said acoustic signals into corresponding first and second electrical control signals, a bistable switch having a first and a second stable state electrically connected to said first tuned transducer, said bistable switch being switched between said first and second stable states in response to control signals from said first tuned transducer and having output means adapted to be coupled to said auxiliary device for controlling one function of the auxiliary device, means coupled between said bistable switch and said first tuned transducer for deactivating said first tuned transducer when said bistable switch is in the second stable state, means coupled between said bistable switch and said second tuned transducer for activating said second transducer when said bistable switch is in its second stable state, a monostable switch having a stable state and an unstable state electrically connected to said second tuned transducer, said monostable switch being switched between its stable state and its unstable state in response to control signals from said second tuned transducer and remaining in its unstable state for a predetermined time interval before returning to its stable state, said monostable switch having output means adapted to be coupled to said auxiliary device for controlling a second function of the auxiliary device when said monostable switch is in its unstable state and means coupled between said monostable switch and said first tuned transducer for activating said first transducer when said monostable switch is in its unstable state.

4. An acoustic switch responsive to acoustic control signals in a predetermined range of frequencies for controlling at least two functions of an auxiliary device coupled to said switch comprising first and second tuned transducers responsive to said acoustic control signals for converting said acoustic signals into electrical signals, a bistable switch having a first and a second stable state coupled to said first tuned transducer, said bistable switch being switched between said first and second stable states in response to electrical signals from said first tuned transducer, means coupling said bistable switch to said auxiliary device for controlling one function of the auxiliary device, means coupled between said bistable switch and said first tuned transducer for deactivating said first tuned transducer when said bistable switch is in the second stable state, means coupled between said bistable switch and said second tuned transducer for activating said second transducer when said bistable switch is in its second stable state, a monostable switch having a stable state and an unstable state coupled to said second tuned transducer, means coupling said monostable switch to said auxiliary device, said monostable switch being switched between its stable state and its unstable state in response to electrical signals from said second tuned transducer and remaining in its unstable state for a predetermined time interval before returning to its stable state and in its unstable state controlling a second function of the auxiliary device, means coupled between said monostable switch and said first tuned transducer for activating said first transducer when said monostable switch is in its unstable state, said first tuned transducer being responsive to acoustic signals transmitted when said monostable switch is in its unstable state, and said bistable switch being switched to its first stable state in response to acoustic signals received while said monostable switch is in its unstable state.

5. The acoustic switch of claim 4 wherein said bistable switch includes a first and second operational amplifier each having first and second input terminals and an output terminal, means for coupling the input terminals of the first operational amplifier to the first tuned transducer, means for coupling the output terminal of the first operational amplifier to the first input terminal of said second operational amplifier, feedback means coupled between the output terminal of the second operational amplifier and the second input terminal thereof so that an acoustic signal detected by the said first tuned transducer produces a change in potential at the output terminal of the second operational amplifier.

6. The acoustic switch of claim 5 wherein said bistable switch includes switch means coupled to the output terminal of said second operational amplifier and operative in accordance with the electrical potential at the output terminal of said second operational amplifier.

7. The acoustic switch of claim 6 wherein said monostable switch includes third and fourth operational amplifiers each having first and second input terminals and an output terminal, means for coupling the input terminals of said third operational amplifier to said second tuned transducer, means for coupling the output terminal of said third operational amplifier to the first input terminal of said fourth operational amplifier, switch means coupled to the output terminal of said fourth operational amplifier and operative in response to the electrical potential on the output terminal of said fourth operational amplifier, first feedback means coupled between the output terminal and the second input terminal of said fourth operational amplifier, and timing means coupled between said switch means and the second input terminal of said fourth operational amplifier so that an acoustic signal detected by said second tuned transducer produces a change in potential at the output terminal of said fourth operational amplifier activating said switch means and said timing means to maintain the switch means in its activated state for a predetermined time interval.

Claims

1. An acoustic switch responsive to acoustic and remotely generated signals in a predetermined frequency range for use in controlling at least two functions of an auxiliary device adapted to be connected to said switch comprising a first tuned transducer, a second tuned transducer, a first switch receiving input from said first transducer and adapted to be connected to said auxiliary for controlling a first function of said device, a second switch receiving input from said second transducer and operative during a conditioning interval and adapted to be connected to said auxiliary device for controlling a second function of said device, means electrically interconnecting said first and second switches and said first and second tuned transducers and arranged such that during said conditioning interval said first transducer is activated to respond to a second acoustic signal to control said first function of said device.

2. An acoustic switch responsive to acoustic and remotely generated signals in a predetermined range of frequencies for use in controlling at least two functions of an auxiliary device adapted to be connected to said switch comprising first and second tuned transducers responsive to said acoustic and remotely generated signals for converting said acoustic signals into corresponding first and second electrical control signals, a bistable switch having a first and second stable state electrically connected to said first tuned transducer, said bistable switch being switched between said first and second stable states in response to control signals from said first tuned transducer and having output means adapted to be coupled to said auxiliary device for controlling one function of the auxiliary device, a monostable switch having a stable state and an unstable state electrically connected to said second tuned transducer, said monostable switch being switched between its stable state and its unstable state in response to control signals from said second tuned transducer and remaining in its unstable state for a predetermined time interval before returning to its stable state, said monostable switch having output means adapted to be coupled to said auxiliary device for controlling a second function of the auxiliary device when said monostable switch is in its unstable state.