CA1318017C - Sound-responsive switching device - Google Patents
Sound-responsive switching deviceInfo
- Publication number
- CA1318017C CA1318017C CA000575211A CA575211A CA1318017C CA 1318017 C CA1318017 C CA 1318017C CA 000575211 A CA000575211 A CA 000575211A CA 575211 A CA575211 A CA 575211A CA 1318017 C CA1318017 C CA 1318017C
- Authority
- CA
- Canada
- Prior art keywords
- sound
- operational amplifier
- switching device
- responsive
- responsive switching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A sound-responsive switching device comprises a transducer for generating a signal representative of sound intensity, a main operational amplifier with positive feedback provided by a parallel combination of a high resistance sensitive to small currents and a capacitor for ensuring the stability of a logic state of the operational amplifier, a secondary operational amplifier acting as a voltage follower to said main operational amplifier, and a switch for an external power circuit, the switch being driven by said secondary operational amplifier into an on or off state in response to the intensity of ambient sound. The device can have a different threshold for switching on than off. It is responsive to hand clapping and particularly suitable providing effects at dances, switching off reading lights at night, and the like. The device also responds to the touching of a metal surface, without mechanical motion or the production of noise.
A sound-responsive switching device comprises a transducer for generating a signal representative of sound intensity, a main operational amplifier with positive feedback provided by a parallel combination of a high resistance sensitive to small currents and a capacitor for ensuring the stability of a logic state of the operational amplifier, a secondary operational amplifier acting as a voltage follower to said main operational amplifier, and a switch for an external power circuit, the switch being driven by said secondary operational amplifier into an on or off state in response to the intensity of ambient sound. The device can have a different threshold for switching on than off. It is responsive to hand clapping and particularly suitable providing effects at dances, switching off reading lights at night, and the like. The device also responds to the touching of a metal surface, without mechanical motion or the production of noise.
Description
This invention relates to a sound responsive switching device, particularly suitable for responding to the clapping of hands and other sudden noises.
Devices are commonly used in discotheques and the like for modulating light intensity in response to sound level. Such devices generally employ complex circuitry and vary the light level continuously in response to the intensity of sound.
An object of the present invention is to provide a simple sound-responsive switching device device that has particularly pleasing characteristics.
According to the present invention there is provided a sound-responsive switching device comprising a transducer for generating a signal representative of sound intensity, a primary operational amplifier with positive feedback provided by a high resistance sensitive to small currents and a capacitor for ensuring the stability of a logic state of the operational amplifier said primary operational amplifier having first and second inputs, said first input being connected to receive said signal and said second input being connected to receive a reference voltage, a secondary operational amplifier acting as a voltage follower to said main operational amplifier, and switching means for an external power circuit having stable on and off status, said switching means being driven by said secondary operational amplifier into an on or off state in response to the intensity of ambient sound.
In a preferred embodiment the transducer is piezo-electric transducer connected such that the state of the operational amplifier is directly sensitive to the peak voltage produced by the transducer.
Preferably, the switching device includes two variable resistances to permit the thresholds for switching on and the thresholds for switching off to be set at different levels. The secondary operational amplifier is conveniently optically coupled to the switching device to isolate the operational amplifiers from the power circuit.
13180t7 The device is extremely simple in construction since the operational amplifier serves as a detector, signal shaper and controller.
The response characteristics of the device are such that it is particularly pleasing for dance occasions. It will respond either to hand clapping or to music with a staccato rhythm. It will also respond to the intensity of continuous sound, above a certain threshold, by an oscillation with ~he frequency roughly proportional to the logarithm of the power of the continuous sound. For music, the device responds sometimes to rhythm, sometimes to intensity, in a varied and entertaining manner.
The device can be used to turn off a reading lamp at night. It can be set so that a loud noise, such as might be generated by snapping a book shut, will turn off the light and that sounds of similar intensity will not turn the light back on.
The device can also be set so that a light can be switched on and off at a certain rate even in the absence of sound with a duty cycle determined by the settings of the variable resistances. For this purpose, the device can, for example, be used to switch on and off Christmas tree lights with a more artistic effect than can be obtained with conventional bimetallic strips.
In the free oscillation mode, the piezo-electric transducer emits a brief sound each time the device switches state. This permits the device to serve as a metronome.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which the single figure is a circuit diagram of a sound-responsive switching device in accordance with the invention.
The device shown in the single figure comprisès a power suppiy stage 1, a control stage 2, and a switching stage 3.
The power stage 1 comprises input terminals A and B
between which is connected the primary winding of a transformer 4, the secondary winding of which is connected to a diode rectifier bridge 5, supplying a voltage stabilizer 6, provided b~ an integrated circuit no. 7805 manufactured by National Semiconductors. A smoothing 1000 micro-farad capacitor is connected across the diode bridge 5. A steady DC voltage is available at the output of the power supplying circuit 1.
The control stage comprises a voltage divider 7, provided by two 180 ohm resistors, a main operational amplifier 8 (no. 1/4LM324 manufactured by National Semiconductors) and a secondary operational amplifier 9 (no.
1/4LM324 manufactured by National Semiconductors) acting as a voltage follower to the main operational amplifier 8.
A piezo-electric transducer 10 is responsive to ambient sound. Positive feedback for the main operational amplifier 8 is provided by a variable ~0 meg- ohm resistor 11 in parallel with 0.1 micro-farad stabilizing capacitor 12.
The capacitor 12 ensures that the operational amplifier 8 remains in a stable state for a certain period of time after switching state.
The inverting input of the operational amplifier 8 is connected to the centre-point of the voltage divider 7, and the non-inverting input is connected to the piezo-electric transducer 10, and to the resistor 11 - capacitor 12 combination. The non-inverting input is also connected through a 10 meg-ohm resistor 13 to the centre-point of a 50 K ohm variable resistor 14 to vary the bias level of the non-inverting input. A 330 K ohm resistor is connected between the two inputs of the operational amplifier 8.
The secondary operational amplifier 9, acting as voltage follower, has its non-inverting input connected to the output of the operational amplifier 8, and an inverting input connected directly to its output. The output of the voltage follower operational amplifier 9 is connected through an LED 15 and a 150 ohm resistor 16 to the supply line of the power supply stage 1. The light emitting diode 15 no. MOC
3010 is optically coupled to a photo sensitive diode 16 connected through resistor 17 to the gate of triac 18.
1~ Elements 15 and 16 are provided by no. MOC3010 manufactured by Motorola. The triac 18 connects a power output C, D to the main power input A, B.
In operation, the peak voltage of the signal produced by the piezo-electric transducer 10 directly determines if there will be a change of state of the operational amplifier 8. This results in the device having a rapid response to brief sounds, such as hand clapping.
The variable resistor 11 controls the sound level at which the required sound intensity for switching occurs.
~0 The variable resistance 14 controls the spread between the switching into the on and off states. For example, switching can be made to occur such that the device will switch on at a lower level than off, and vice versa.
The device is particularly desirable and pleasing on dance occasions. If the two variable resistors are adjusted so as to have a high threshold for a transition to the on stage, and a low threshold for the transition to the off stage, the device is ideal for controlling a night reading light. A person in bed merely has to close his book suddenly to switch off the light, which will not come on again unless he makes a louder noise. A low level noise occurring in the night will not switch on the light and cause him to wake up. The control of the sensitivity of the variable resistor 11 can be such that the device will switch, and if connected to a lamp the lamp will come on and off, at a certain rate even in the absence of noise~ In this configuration, the device can be used to control Christmas tree lights with a certain duty cycle, the resistor 14 controlling the duty cycle and the resistor 11 controlling the repetition rate, to permit a desired artistic effect to be produced.
Since the piezo-electric transducer gives off a brief sound each time the device switches, the device can be made to serve, for example, as a metronome.
Since the inputs of the operational amplifier are sensitive to very small currents, the lamp can be switched on and off by touching these inputs because of the voltages induced by the stray fields when the person touches.
Continuous touching has an effect equivalent to a continuous sound (oscillations), while a short touch has an effect similar to hand clapping (switching on and off). In this embodiment, the negative feedback input is connected by a wire to an easy-to-touch metal surface so that the device can be operated, if necessary, without any sound by touching the metal surface.
Devices are commonly used in discotheques and the like for modulating light intensity in response to sound level. Such devices generally employ complex circuitry and vary the light level continuously in response to the intensity of sound.
An object of the present invention is to provide a simple sound-responsive switching device device that has particularly pleasing characteristics.
According to the present invention there is provided a sound-responsive switching device comprising a transducer for generating a signal representative of sound intensity, a primary operational amplifier with positive feedback provided by a high resistance sensitive to small currents and a capacitor for ensuring the stability of a logic state of the operational amplifier said primary operational amplifier having first and second inputs, said first input being connected to receive said signal and said second input being connected to receive a reference voltage, a secondary operational amplifier acting as a voltage follower to said main operational amplifier, and switching means for an external power circuit having stable on and off status, said switching means being driven by said secondary operational amplifier into an on or off state in response to the intensity of ambient sound.
In a preferred embodiment the transducer is piezo-electric transducer connected such that the state of the operational amplifier is directly sensitive to the peak voltage produced by the transducer.
Preferably, the switching device includes two variable resistances to permit the thresholds for switching on and the thresholds for switching off to be set at different levels. The secondary operational amplifier is conveniently optically coupled to the switching device to isolate the operational amplifiers from the power circuit.
13180t7 The device is extremely simple in construction since the operational amplifier serves as a detector, signal shaper and controller.
The response characteristics of the device are such that it is particularly pleasing for dance occasions. It will respond either to hand clapping or to music with a staccato rhythm. It will also respond to the intensity of continuous sound, above a certain threshold, by an oscillation with ~he frequency roughly proportional to the logarithm of the power of the continuous sound. For music, the device responds sometimes to rhythm, sometimes to intensity, in a varied and entertaining manner.
The device can be used to turn off a reading lamp at night. It can be set so that a loud noise, such as might be generated by snapping a book shut, will turn off the light and that sounds of similar intensity will not turn the light back on.
The device can also be set so that a light can be switched on and off at a certain rate even in the absence of sound with a duty cycle determined by the settings of the variable resistances. For this purpose, the device can, for example, be used to switch on and off Christmas tree lights with a more artistic effect than can be obtained with conventional bimetallic strips.
In the free oscillation mode, the piezo-electric transducer emits a brief sound each time the device switches state. This permits the device to serve as a metronome.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which the single figure is a circuit diagram of a sound-responsive switching device in accordance with the invention.
The device shown in the single figure comprisès a power suppiy stage 1, a control stage 2, and a switching stage 3.
The power stage 1 comprises input terminals A and B
between which is connected the primary winding of a transformer 4, the secondary winding of which is connected to a diode rectifier bridge 5, supplying a voltage stabilizer 6, provided b~ an integrated circuit no. 7805 manufactured by National Semiconductors. A smoothing 1000 micro-farad capacitor is connected across the diode bridge 5. A steady DC voltage is available at the output of the power supplying circuit 1.
The control stage comprises a voltage divider 7, provided by two 180 ohm resistors, a main operational amplifier 8 (no. 1/4LM324 manufactured by National Semiconductors) and a secondary operational amplifier 9 (no.
1/4LM324 manufactured by National Semiconductors) acting as a voltage follower to the main operational amplifier 8.
A piezo-electric transducer 10 is responsive to ambient sound. Positive feedback for the main operational amplifier 8 is provided by a variable ~0 meg- ohm resistor 11 in parallel with 0.1 micro-farad stabilizing capacitor 12.
The capacitor 12 ensures that the operational amplifier 8 remains in a stable state for a certain period of time after switching state.
The inverting input of the operational amplifier 8 is connected to the centre-point of the voltage divider 7, and the non-inverting input is connected to the piezo-electric transducer 10, and to the resistor 11 - capacitor 12 combination. The non-inverting input is also connected through a 10 meg-ohm resistor 13 to the centre-point of a 50 K ohm variable resistor 14 to vary the bias level of the non-inverting input. A 330 K ohm resistor is connected between the two inputs of the operational amplifier 8.
The secondary operational amplifier 9, acting as voltage follower, has its non-inverting input connected to the output of the operational amplifier 8, and an inverting input connected directly to its output. The output of the voltage follower operational amplifier 9 is connected through an LED 15 and a 150 ohm resistor 16 to the supply line of the power supply stage 1. The light emitting diode 15 no. MOC
3010 is optically coupled to a photo sensitive diode 16 connected through resistor 17 to the gate of triac 18.
1~ Elements 15 and 16 are provided by no. MOC3010 manufactured by Motorola. The triac 18 connects a power output C, D to the main power input A, B.
In operation, the peak voltage of the signal produced by the piezo-electric transducer 10 directly determines if there will be a change of state of the operational amplifier 8. This results in the device having a rapid response to brief sounds, such as hand clapping.
The variable resistor 11 controls the sound level at which the required sound intensity for switching occurs.
~0 The variable resistance 14 controls the spread between the switching into the on and off states. For example, switching can be made to occur such that the device will switch on at a lower level than off, and vice versa.
The device is particularly desirable and pleasing on dance occasions. If the two variable resistors are adjusted so as to have a high threshold for a transition to the on stage, and a low threshold for the transition to the off stage, the device is ideal for controlling a night reading light. A person in bed merely has to close his book suddenly to switch off the light, which will not come on again unless he makes a louder noise. A low level noise occurring in the night will not switch on the light and cause him to wake up. The control of the sensitivity of the variable resistor 11 can be such that the device will switch, and if connected to a lamp the lamp will come on and off, at a certain rate even in the absence of noise~ In this configuration, the device can be used to control Christmas tree lights with a certain duty cycle, the resistor 14 controlling the duty cycle and the resistor 11 controlling the repetition rate, to permit a desired artistic effect to be produced.
Since the piezo-electric transducer gives off a brief sound each time the device switches, the device can be made to serve, for example, as a metronome.
Since the inputs of the operational amplifier are sensitive to very small currents, the lamp can be switched on and off by touching these inputs because of the voltages induced by the stray fields when the person touches.
Continuous touching has an effect equivalent to a continuous sound (oscillations), while a short touch has an effect similar to hand clapping (switching on and off). In this embodiment, the negative feedback input is connected by a wire to an easy-to-touch metal surface so that the device can be operated, if necessary, without any sound by touching the metal surface.
Claims (11)
1. A sound-responsive switching device comprising a transducer for generating a signal representative of sound intensity, a primary operational amplifier with positive feedback provided by a high resistance sensitive to small currents and a capacitor for ensuring the stability of a logic state of the operational amplifier said primary operational amplifier having first and second inputs, said first input being connected to receive said signal and said second input being connected to receive a reference voltage, a secondary operational amplifier acting as a voltage follower to said main operational amplifier, and switching means for an external power circuit having stable on and off status, said switching means being driven by said secondary operational amplifier into an on or off state in response to the intensity of ambient sound.
2. A sound-responsive switching device as claimed in claim 1 wherein said transducer is a piezo-electric transducer connected such that the state of the operational amplifier is directly sensitive to the peak voltage produced by the transducer.
3. A sound-responsive switching device as claimed in claim 1 said high resistance is variable to permit the threshold level of said main operational amplifier to be adjusted.
4. A sound-responsive switching device as claimed in claim 3 further comprising a second variable resistance acting as a voltage divider and connected to the non-inverting input of the main operational amplifier through a resistance to permit the difference in threshold levels for the two states to be varied.
5. A sound-responsive switching device as claimed in claim 4 biassed such that in the absence of sound said device can be set to switch between the on and off states with a duty cycle determined by the settings of said variable resistances.
6. A sound-responsive switching device as claimed in claim 1 wherein said secondary operational amplifier is optically coupled to said switching device to isolate said operational amplifiers from the power circuit.
7. A sound-responsive switching device as claimed in claim 6 wherein said switching device is a semi-conductor switching device.
8. A sound-responsive switching device as claimed in claim 6 wherein said switching device is a triac.
9. A sound-responsive switching device as claimed in claim 1 further comprising a power input connected to a power output through said switching device, a transformer connected to said power input, and a power supply circuit connected to a secondary winding of said transformer providing a low d.c voltage to said operational amplifiers.
10. A sound-responsive switching device as claimed in claim 1 wherein one input of the main operational amplifier is connected directly to the switching means.
11. A sound-responsive switching device as claimed in claim 1 wherein one input of the main operational amplifier is directly connected to touchable means such that the device can be operated by simple touching as well as by sound.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000575211A CA1318017C (en) | 1988-08-19 | 1988-08-19 | Sound-responsive switching device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000575211A CA1318017C (en) | 1988-08-19 | 1988-08-19 | Sound-responsive switching device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1318017C true CA1318017C (en) | 1993-05-18 |
Family
ID=4138584
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000575211A Expired - Fee Related CA1318017C (en) | 1988-08-19 | 1988-08-19 | Sound-responsive switching device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1318017C (en) |
-
1988
- 1988-08-19 CA CA000575211A patent/CA1318017C/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |