Note: Descriptions are shown in the official language in which they were submitted.
00291-2/PPPPPl
ACOUSTIC SWITCH
Acoustic switches are used to replace manually
operated on-off switches such as light switches or
switches for other household appliances. Acoustic
switches are triggered by the presence or absence ~f
sound of a particular t~p~. For instance, U.S. Patent
3,949,366 to Spillar, et al., discloses a system for
turning on and off appliances which is activated by a
fixed frequency of~sound generated by a transmitter.
Another system shown in U.S. Patent 4,408,308 to Smith,
_ al., shows a switch which automatically turns off in
the event that no sound is detected for a fixed period
of time. This type of switch is useful for turning off
lights or o~her appliances when people leave a room.
The present invention is a light indicator
for an acoustic switch which is connected so that this
single indicator will produce a light only when both
A/C p~wer is supplied to the switch and an appliance is
plugged into the switch and turned on ready to receive
power. The switch has a microphone which produces an
electrical signal when sound is detected. This elec
trical signal is supplied to an activating circuit which
will activate a trigger device to couple the A/C line
power to the connected appliance.
In the preferred embodiment, the light indi-
cator is a combination of a resistance and a light emit-
ting diode in series coupled across the tri~gering de-
vice. The trigqering device is a triac switch. Four
flip flops are used to activate the triac switch when
twb closely spaced sounds, such as two hand-claps, are
3S detected.
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The first flip-flop receives an amplified
signal from the microphone, causing it to produce a
positive output. This output is coupled to the clock
input of a second flip-flop and also charge~ a capaci-
tor coupled to a data input of ~he second flip flop.
Thus, a first sound will clock the first flip-flop to
produce a positive input to the second flip~flop after
about ~ half second delay. This delay is the period of
time it takes the capacitor to charge. The first flip-
flop is then reset after a half second when a capacitor
coupled to the reset inport becomes charged. If a~sec-
ond sound appears after this reset and before the dis-
charge of the capacitor coupled to the input of the
second flip-flop, the first flip-flop will be toggled
again, thereby clocking an output from the second flip-
flop.
The output of the second flip-flop will clock
the third and fourth flip-flops, which are connected
together to provide sufficient current to turn on the
triac switch. The data inputs of the third and fourth
flip-flops are coupled to the negative output of one of
the third and fourth flip-flops. This causes the flip-
~lops to change state each time, thereby alternately
turning on and off the triac switch.
The indicator light enables a user to deter-
mine both ~13 whether the switch is coupled to A/C power
and ~2) whether an appliance both plugged into the switch
and is turned on. This dual function indicator enables
a user to determine at a glance whether the system is
in operating condition without requiring a user to check
the on/off switch of the appliance itself or the other
connections. When a user makes two successi~e sounds,
sUch as hand claps, the switch will be activated and
the indicator light will turn off, indicating that power
has been supplied to the appliance~ This is particu~
la~ly useful for some appliances, such as a television,
which take some time to warm up. Without the indicator
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light, a user would not know immediately that he had suc
cessfully turned on the television.
The invention also has an amplifier with suf-
ficient gain to enable hand claps from as far away as
twenty feet to be detected. Since this large amount of
gain may also cause background noises to set off a switch,
the sensitivity of the switch is user ad~justable.
Preferably~ a resistive potentiometer is connected to the
input of the first flip-flop and is user accessible,
enabling the user to adjust the sensitivity of the switch.
For a fuller understanding of the nature and
advantages of the invention, reference should be made to
the ensuing detailed description taken in conjunction with
the accompanying drawing, which is a schematic view of a
preferred embodiment of the present invention.
The drawing is a schemakic view of the acoustic
switch of the present invention. A/C line power is coupled
to a pair of input terminals 10~ An appliance to be
switched on and off is connected to a pair of output ter-
minals 12. A triac sitch 14 will couple line power to the
appliance coupled to output 12. A triggering signal ~or
triac 14 is provided through the operation of flip-flops
16, 18, 20, and 22. These flip-flops are enabled by a
signal for a microphone 24 which is amplified by a tran-
sistor 26. Rectified D/C power for the circuit is provided
by a Zener diode 28. A negative grol~nd return is provided
through diode 30 and resistors 32, 34, and capacitor 36.
A filter capacitor 38 is coupled across the posi-
tive and negative D/G lines. A limiting resistor 40 pro-
vides ~/C power to the flip-flops.
'b~
In operation, when microphone 24 detects a
sound, it operates to couple the base of transistor 26
to ground. This turns off transistor 26, pulling its
collector high and presenting the high signal to the
clock input 42 of flip-flop 16. Data input 44 for the
flip-flop 16 is always held high by the positive power
supply. The size of the signal xe~uired to activate
clock input 42 is controlled by potentiometers 46 and
48 in conjunction with resistor S0. Potentiometer 48
is adjusted when the switch is manufactured to compen-
sate for differences due to the particular components
used. Potentiometer 46 is user accessible, enabling a
user to adjust the~sensitivity of the device.
A resistor 52 is provided to perform current
limiting for microphone 24. Resistors 54, 56, 58, and
60 are used for biasing transistor 26. Transistor 26
preferably has a gain of approximately 200 Hfe. This
provides a sensitivity for audio noises up to a range
of approximately twenty feet from the acoustic switch.
Upon receiving a clock signal at input 42,
flip~flop 16 will produce a positive output at output
62. This output is coupled to a clock input 64 of flip-
~lop 18. However, the first sound to appear will not
cause flip-flop 18 to toggle since a data input 66 would
normally be low. However, t~is first clock signal will
char~e a capacitor 68 through a resistor 70 to give a
high level data input for flip-flop 18. This high-level
input to clock input 34 will disappear when capacitor
68 discharges after output 62 of flip-flop 16 is reset
to zero.
Output 62 of flip-flop 16 will be reset to
zero when the high level signal applied across resistor
72 and capacitor 74 charges up capacitor 74 to present
a high level input to a reset input 76 of flip-flop 16.
The time constants of capacitors 68 and 74 are chosen
so~that two sounds must occur more than one-half second
and approximately less than one second apart. The
second sound must thus occur after flip-flop 16 has
been reset and before the charge on capacitor 68 has
decayed sufficiently to eliminate the positive signal
at i~put 66 of flip-flop 18. The second sound appearing
in this time window will trigger flip-flop 18 giving a
positive output on output 78 of flip-flop 18.
When flip-flop 18 has a positive output on
output 78, this will trigger clock inputs 80 and 32 of
10 1ip-flops 22 and 20, respectively. Because data inputs
84 and 86 are initially high, both flip-flops will tog-
gle, producing a high level output on outputs 88 and
90. These outputs are coupled through resistors 92 and
94, respectively, to the trigger input of triac 1~.
- A low level will appear on the inverse output
96 of flip-flop 22, which is coupled to the data inputs
84 and 86 of flip-flops 22 and 24. Thus, the next set
of two successive sounds will produce a low level out-
put of flip-flops 20, 22, thereby turning off triac 14.
A resistor 98 and an LED 100 are coupled
across triac 14. Current will 10w through resistor 98
and LED 100 only when line power is coupled to inputs
10 and an appliance is coupled to output 12. In addi-
~tion, the appliance must be turned on to receive power,
thereby enabling current flow. When triac 14 is trig-
gered, current will flow through triac 14, thereby by-
passing resistor 98 and LED lO0. The light fxom LED
100 will thus disappear, indicating that the appliance
has been connected.
As will be understood by those familiar wi~h
the art, the present invention can be embodied in other
forms without departing from the spixit or essential
characteristics thereof. For example, a device other
than an LED could be used to provide a light when triac
14 has not been triggered, or another trigger device
could be used in place of triac 14. Alternate circuit
configurations other than the flip-flops shown could be
used to provide the triggering signal to triac 14.
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Accordingly, the foregoing embodiments are intended to
be illustrative of, but not limiting of, the scope of
the invention, which is set forth in the following
claims.