U.S. patent number 3,693,110 [Application Number 05/118,049] was granted by the patent office on 1972-09-19 for audible signal or alarm device including two variable frequency unijunction transistor oscillators.
This patent grant is currently assigned to C. A. Briggs Company. Invention is credited to Charles A. Briggs, Jr., Walter H. Vogelsberg.
United States Patent |
3,693,110 |
Briggs, Jr. , et
al. |
September 19, 1972 |
AUDIBLE SIGNAL OR ALARM DEVICE INCLUDING TWO VARIABLE FREQUENCY
UNIJUNCTION TRANSISTOR OSCILLATORS
Abstract
An audible signal or alarm circuit capable of selectively
providing different output signals is disclosed. The circuit is
capable of providing a steady output signal, a varying frequency
output signal, different rates at which the frequency of the output
signal is varied and different basic varying frequency signals. The
alarm circuit may be used alone or in connection with any sensing
or measuring circuitry, such as fire detectors, intrusion detection
systems or the like. In addition, the different output signals can
be selectively programmed using simple devices such as timing
circuits, condition responsive circuits or the like. The alarm
circuit comprises a pair of unijunction transistors, an amplifier
circuit, a speaker and switching means used to obtain the various
different output signals.
Inventors: |
Briggs, Jr.; Charles A.
(Glenside, PA), Vogelsberg; Walter H. (Carversville,
PA) |
Assignee: |
C. A. Briggs Company (Glenside,
PA)
|
Family
ID: |
22376229 |
Appl.
No.: |
05/118,049 |
Filed: |
February 23, 1971 |
Current U.S.
Class: |
331/47; 331/111;
331/179; 331/177R; 340/328; 340/384.7 |
Current CPC
Class: |
G08B
19/00 (20130101); G08B 3/10 (20130101) |
Current International
Class: |
G08B
19/00 (20060101); G08B 3/10 (20060101); G08B
3/00 (20060101); G08b 003/10 (); G08b 019/00 ();
H03b 003/04 () |
Field of
Search: |
;331/47,111,177R,179
;340/328,384E |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lake; Roy
Assistant Examiner: Grimm; Siegfried H.
Claims
What is claimed is:
1. An audible signal circuit comprising: A first unijunction
transistor having an emitter, a first base and a second base; a
source of voltage, a first resistor connected between said source
of voltage and said first base of said first unijunction
transistor; a point of common potential; a second resistor
connected between said point of common potential and said second
base of said first unijunction transistor; a first variable
resistor connected between said voltage source and said emitter of
said first unijunction transistor; a first capacitive circuit
connected between said emitter of said first unijunction oscillator
and said point of common potential; means coupled to said first
capacitive circuit for selectively changing the capacitance of said
first capacitive circuit; a second unijunction transistor having an
emitter, a first base and a second base; a third resistor connected
between said second base of said second unijunction transistor and
said point of common potential; a fourth resistor coupled between
said first base of said second unijunction transistor and said
source of voltage; a second variable resistor connected between
said emitter of said second unijunction transistor and said voltage
source; a second capacitive circuit connected between said emitter
of said second unijunction transistor and said point of common
potential; means coupled to said second capacitive circuit for
selectively changing the capacitance of said second capacitive
circuit; a fifth resistor connected between said emitter of said
first unijunction transistor and said emitter of said second
unijunction transistor; a diode connected in series with said
fourth resistor in such a manner that its cathode is connected to
said first base of said second unijunction transistor; a switch
connected between said point of common potential and the common
point of the anode of said diode and said fourth resistor; a
transistor amplifier having an input and an output; means to couple
said amplifier input to said emitter of said first unijunction
transistor; and a loudspeaker coupled to said amplifier output.
2. An audible signal circuit as defined in claim 1 wherein said
first capacitive circuit includes at least two capacitors serially
connected between the emitter of said first unijunction transistor
and said point of common potential; said means for changing the
capacitance of said first capacitive circuit is a switch connected
to short out at least one of said serially connected capacitors
when said switch is closed; said second capacitor circuit comprises
at least two parallel capacitors connected between said point of
common potential and said emitter of said second unijunction
transistor and said means for changing the capacitance of said
second capacitive circuit comprises a switch so connected as to
remove at least one of said two parallel capacitors from said point
of common potential.
3. An audible signal circuit as defined in claim 1 wherein said
first capacitive circuit and said means for changing the
capacitance of said first capacitive circuit comprises a first
variable capacitor connected between said point of common potential
and said emitter of said first unijunction transistor and wherein
said second capacitive circuit and said means for changing the
capacitance of said second capacitive circuit comprises a second
variable capacitor between said point of common potential and said
emitter of said second unijunction transistor.
4. An audible signal circuit as defined in claim 1 wherein a
programmable control circuit is coupled to said switch, to said
means for changing the capacitance of said first capacitive circuit
and to said means for changing the capacitance of said second
capacitive circuit.
5. An audible signal circuit as defined in claim 1 wherein said
first capacitive circuit includes a first plurality of capacitors,
said means for selectively changing the capacitance of said first
capacitive circuit comprises a first switching means for
selectively switching any number of said first plurality of
capacitors between said emitter of said first unijunction
transistor and said point of common potential; and wherein said
second capacitive circuit includes a second plurality of capacitors
and said means for selectively changing the capacitance of said
second capacitive circuit comprises a second switching means for
selectively switching any number of said second plurality of
capacitors between said emitter of said second unijunction
transistor and said point of common potential.
6. An audible signal circuit as defined in claim 2 wherein a
programmable control circuit is coupled to said switch connected to
short out at least one of said serially connected capacitors, to
said switch so connected as to remove at least one of said two
parallel capacitors from said point of common potential and to said
switch connected between said point of common potential and the
common point of the anode of said diode and said fourth
resistor.
7. An audible signal circuit as defined in claim 3 wherein a
programmable control circuit is coupled to said first variable
capacitor, to said second variable capacitor and to said
switch.
8. An audible signal circuit as defined in claim 5 wherein a
programmable control circuit is coupled to said first switching
means, to said second switching means and to said switch.
Description
BACKGROUND OF THE INVENTION
This invention relates to audible signal devices and more
particularly to an audible signal circuit capable of selectively
providing different output signals.
In recent years it has become apparent that the conventional
audible signal or alarm devices, such as steady signals, horns,
buzzers or the like are not easily heard in a noise environment or
people tend to ignore these signals, probably because such signals
or alarms have become too common place and no longer attract
attention. Also some of the higher frequency steady signals cannot
be heard at all by older people.
Recently, new audible signal or alarm devices such as the warblers
and varying frequency devices have been invented to overcome the
problems encountered with the prior art conventional alarms or
signal devices. Generally, the presently available varying
frequency devices operate on a fixed frequency and fixed rate of
varying the frequency. While these devices are normally readily
hard in a noise environment, they are limited in scope because the
frequency and variation rate are fixed. Thus, if one wanted to
indicate specific different conditions by means of these prior art
varying frequency signal devices, he would have to use a separate
varying frequency signal device each fixed at a different frequency
and/or rate for each of the desired conditions.
SUMMARY OF THE INVENTION
This invention provides a varying frequency audible signal or alarm
circuit capable of selectively providing a fixed signal output, and
a varying frequency output signal, the frequency of which can be
selectively varied at different rates. In addition the basic
frequency of the device can be changed. Thus, not only can the rate
of frequency variation be changed but in addition the basic
frequency of the signal being varied can also be selectively
changed. With this device one can obtain a plurality of different
output signals with a single alarm or signal device. These
different output signals can be selectively programmed to indicate
specific conditions, the passage of a fixed amount of time or the
like.
The alarm or signal circuit comprises a pair of unijunction
oscillators so interconnected that one of the oscillators frequency
modulates the other oscillator. A transistor amplifier is connected
to the output of the oscillator circuit to obtain an amplified
frequency varying signal. Switches or other means are provided to
selectively obtain different variation rates and different
oscillator frequencies. A steady output signal can also be obtained
by means of a switch. These switches or selector means may be
automatically operated by simple programming means.
It is therefore an object of this invention to provide an audible
alarm or signal device.
Another object of this invention is to provide a steady tone
audible signal or alarm device.
A further object of this invention is to provide an audible signal
or alarm device having a varying frequency output signal.
A further object of this invention is to provide an audible signal
or alarm device having a varying frequency output signal, the
frequency variation rate of which can be selectively changed.
A further object of this invention is to provide an audible signal
or alarm oscillator circuit having means for selectively changing
the frequency of oscillation.
A still further object of this invention is to provide an audible
signal or alarm capable of providing programmed selected output
signals.
BRIEF DESCRIPTION OF THE DRAWING
The above mentioned and other objects of the invention will become
readily apparent from the following detailed description of the
invention when read in conjunction with the annexed drawing in
which:
FIG. 1 is a circuit diagram showing a preferred embodiment of the
audible signal or alarm circuit of this invention;
FIG. 2 shows in block diagram form the audible signal circuit used
in conjunction with sensing circuitry and programmable control
circuit for selectively changing the output of the signal or alarm
circuit; and
FIG. 3 is a pictorial view showing how the audible signal or alarm
circuit may be packaged.
DESCRIPTION OF THE INVENTION
As shown in FIG. 1, the audible signal or alarm circuit 1 comprises
a first oscillator having an unijunction transistor Q1 and a second
oscillator having an unijunction transistor Q2. The first
oscillator in addition to unijunction transistor Q1 comprises a
resistor 6 connected between a source of positive voltage V+ and
one of the bases of unijunction transistor Q1; a resistor 8
connected between the ground 17 and the second base of unijunction
transistor Q1; a first capacitor 5 and a second capacitor 7
serially connected between the emitter of unijunction transistor Q1
and ground 17; and a variable resistor 10 connected between the
emitter of unijunction transistor Q1 and voltage source V+ .
Similarly, the second oscillator in addition to unijunction
transistor Q2 comprises a variable resistor 12 connected between
source V+ and the emitter of unijunction transistor Q2; a capacitor
11 connected between ground 17 and the emitter of unijunction
transistor Q2; a resistor 18 connected between one base of
unijunction transistor Q2 and ground 17 and a resistor 14 and a
diode D1 serially connected between source V+ and the second base
of unijunction transistor Q2. The two basic oscillator circuits are
connected together by means of a resistor 20 connected between the
emitter of unijunction transistor Q1 and the emitter of unijunction
transistor Q2. An output signal is taken from the emitter of
unijunction transistor Q1. This output signal is applied to an
amplifier circuit comprising the transistors Q3 and Q4 by means of
a resistor 16 connected between the base of transistor Q3 and the
emitter of unijunction transistor Q1. A speaker is connected
between the collectors of amplifier transistors Q3 and Q4 to
provide an audible output.
The oscillator circuit just described which is made up of two basic
unijunction oscillators provides a varying frequency output signal.
Oscillator circuits of this type are known in the art. Furthermore,
varying frequency devices using two basic unijunction transistor
oscillator circuits are also known in the art. However, in these
prior art circuits, single capacitors are used in place of
capacitors 5 and 7 and 9 and 11, no diode such as D1 is located in
one of the base circuits of the second unijunction transistor and
the resistors 10 and 12 are generally fixed resistors. With this
type of device, the output signal varies at a fixed rate and the
frequency of the oscillators is also fixed.
With the circuit shown in FIG. 1, different outputs can be
selectively obtained by means of the switches SW1, SW2 and SW3 and
by means of variable resistors 10 and 12. Closing of SW1 shorts out
capacitor 7 thereby leaving only capacitor 5 in the circuit.
Removing one of the two series capacitors will increase the
capacitance of the oscillator circuit and therefore change the
frequency of oscillation. In a similar fashion closing of switch
SW2 adds the capacitor 9 in parallel with capacitor 11 thereby
changing the frequency of this oscillator circuit. The two
oscillators operate in such a fashion that the second oscillator
that is the one having unijunction transistor Q2 (herein after
referred to as the Q2 oscillator) frequency modulates the output of
the first or Q1 unijunction transistor oscillator (hereinafter
referred to as the Q1 oscillator). In other words the Q2 oscillator
establishes the rate at which the frequency of the output signal
varies. It is, therefore, obvious that the closing of switch SW2
will change the rate of variation of the output signal. Changing of
the resistances of variable resistors 10 and 12 will also change
the frequencies of the oscillators and therefore the basic output
frequency and/or rate of variation of the output. The changing of
the resistance of resistor 10 alone will only change the basic
frequency of the output signal whereas the changing of resistor 12
alone will only change the rate of variation of the output signal.
Of course changing the resistance of both resistors 10 and 12 will
affect both the frequency and the rate.
From the foregoing description of the function of switches SW1 and
SW2 and variable resistors 10 and 12, it is apparent that with the
circuit of FIG. 1 the basic frequency of the output signal, the
rate at which the output signal varies or both can be selectively
changed. Closing of switch SW1 alone changes only the frequency;
closing of SW2 alone changes only the rate of variation; and
closing of both these switches changes both the frequency and rate.
Further selective changes in frequency, rate or both can be
obtained by varying either or both of the variable resistors 10 and
12.
While only two capacitors and a single switch are shown in each of
the oscillator circuits, it should be obvious that additional
capacitors can be connected in series or parallel or in a
series-parallel arrangement in each of the oscillators with
appropriate switches to selectively obtain any desired capacitance.
Also the capacitors shown could be replaced with variable
capacitors or a plurality of variable capacitors. With these more
elaborate arrangements, a greater number of distinct and readily
discernible output signals can be obtained.
In order to avoid confusion or misunderstanding of what is means by
the terms change in the basic frequency of the output signal and
change in rate of variation of the output signal as they are used
throughout this specification, the term change in basic frequency
is here defined as being the frequency of the Q1 oscillator which
is changed by closing switch SW1. The output of the Q1 oscillator
is frequency modulated by the Q2 oscillator. Thus changing the
frequency of the Q1 oscillator changes the carrier or fundamental
frequency which is varied or modulated by the Q2 oscillator. From
this definition is is obvious that output signal will be distinctly
different since the frequency of the Q1 oscillator is noticeably
changed by the opening and closing of switch SW1. The term rate of
variation of the output signal is here defined as being the rate at
which the frequency of the output signal of the Q1 oscillator is
changed by the Q2 oscillator which frequency modulates the signal
from the Q1 oscillator. Since the frequency of the Q2 oscillator is
noticeably changed by the opening and closing of switch SW2 it is
obvious that the rate at which the frequency of the output signal
applied to the transistor amplifier changes will also be noticeably
changed.
As has been mentioned above, the signal or alarm circuit of this
invention can also provide a non-varying or steady output signal.
This steady output signal is obtained by closing switch SW3 When
switch SW3 is closed the Q2 oscillator is rendered inoperative and
therefore the output of the Q1 oscillator is not frequency
modulated. The frequency of this steady output signal can, of
course, be changed by opening and closing switch SW1 or by varying
resistor 10.
From the foregoing description of the overall operation of the
circuit of FIG. 1, it is obvious that this circuit provides a
versatile audible signal or alarm device. With switches SW1, SW2
and SW3 all open, a first audible output signal varying at a first
rate will be obtained from speaker 15. When switch SW1 is closed
and switches SW2 and SW3 are opened a second audible output signal
varying at the first rate will be obtained. If switches SW1 and SW3
are opened and switch SW2 is closed, the above mentioned first
audible output signal varying at a second rate will be obtained. If
switches SW1 and SW2 are closed and switch SW3 is open, the above
mentioned second audible output signal varying at the above
mentioned second rate is obtained. If switch SW3 is closed and
switch SW1 is opened (the position of switch SW2 when switch SW3 is
closed is of no significance since oscillator Q2 is rendered
inoperative), a steady single frequency audible output signal will
be obtained. If both switches SW1 and SW3 are closed, a steady
single frequency output signal different in frequency from the
output signal obtained when switch SW1 is open, will be obtained.
Thus by the mere opening and closing of switches SW1, SW2 and SW3
six different output signals are provided. As has been mentioned
above, additional different outputs can be obtained by varying
resistors 10 and 12 or by adding additional capacitors and switches
or by using variable capacitors. Thus, it is quite apparent that
the circuit of FIG. 1 provides a very versatile signal or alarm
device. The circuit of FIG. 1 can be powered by conventional
transistor dry cells and the amplifier provides a considerably
amount of output power. No additional amplification is required to
provide an audible signal that can be heard for a considerably
distance from the site of the device. Of course, additional
amplification can be added but is not needed for most
applications.
FIG. 2 shows in block diagram form a system in which the alarm or
signal circuit 1 of FIG. 1 can be readily incorporated. As shown in
FIG. 2, this system comprises the sensing circuitry 2, a
programmable control device 3, and the audible signal or alarm
circuit 1. Sensing circuit 2 can be any circuit capable of sensing
a condition and does not form a part of this invention. For
example, if the system shown in FIG. 2 is a security system,
sensing circuitry 2 could include fire detectors, burglar detection
apparatus, temperature sensors, water or moisture detectors or the
like. Any or all of these systems could be included in such a
security system. The output of sensing circuitry 2 is applied to
programmable control device 3. Programmable control device 3 is
used to select the proper one of the multitude of output signals
available from signal device 1 and as will be apparent later can be
used to program these outputs in any particular desired manner or
sequence.
For purposes of clarity in describing the operation of the system
shown in FIG. 2, assume that sensing circuitry 2 includes fire
detection devices, burglar detection devices and water detection
devices. In this case three separate output lines could be
connected between sensing circuitry 2 and programmable control
device 3, or if coded signals are used, a single output would
suffice. The type of circuitry used will, of course, depend upon
the type of output signals emanating from sensing circuitry 2 and
the nature of the control of signal device 1 that is to be
obtained. In any event as will be apparent, the circuitry used for
programmable control device 3 is in all cases conventional well
known circuitry. If now sensing circuitry 2 detects a fire in the
protected area, a signal will be transmitted to control device 3
from sensing circuitry 2 and control device 3 will actuate signal
device 1 and open or close the appropriate switches, or the
equivalent as the case may be. Thus, control device 2 will control
signal device 1 to obtain a particular output signal that is
selected as the fire alarm signal. For example, if the circuitry of
FIG. 1 is used, the fire signal could be the output obtained when
switches SW1, SW2 and SW3 are all open. If on the other hand a
burglar is detected, control device 2 could operate to close SW1
and leave switches SW2 and SW3 open, thereby obtaining a second
signal different from the fire alarm signal. A distinct water alarm
signal could be obtained by closing switch SW2 and opening switches
SW1 and SW2. Similarly, a combination burglar and fire alarm signal
could be obtained by having programmable control device 3 close
both switches SW1 and SW2 and open switch SW3, etc. Thus,
programmable control device 3 programs audible signal device 1 in
such a manner that a predetermined distinct output is obtained for
each condition sensed. In this case programmable control device can
be any known electromechanical device capable of opening and
closing switches or if electronic switches are used control device
3 can be an electronic control circuit.
The above specific example of a system using the signal or alarm
circuit 1 is given by way of example only. This audible signal or
alarm circuit can be used in any environment in which it is desired
to provide an audible output signal or preferably a plurality of
different audible output signal or preferably a plurality of
different audible signals. Similarly, the specific programmable
control device described above is given by way of example only to
show that audible signal or alarm device 1 can be programmed to
provide different output signals to impart specific information.
Programmable control device 3 could be a simple timing circuit used
to program audible signal device 1 to produce specific output
signals at certain times. For example, if signal or alarm device 1
were used in a fire detection system or in a machine monitor to
indicate a breakdown or the like, programmable control device 3
could be a simple timing circuit that programs audible signal or
alarm device 1 to produce a first output signal when the fire or
breakdown first occurs and at a later time a second signal if no
response is made to the first signal, and still at a later time a
third signal if no response is made to the first and second signals
and so forth. In this case, it is obvious that simple well known
timing and control circuits could be used for programmable control
circuit 3. One having ordinary skill in the art could think of many
other different examples of circuits that can be used for
programmable control circuit 3. The circuit used, of course,
depends upon the result desired. Thus, the important fact is not
the specific circuitry used in programmable control circuit 3, but
is the fact that audible signal or alarm device 1 can be programmed
to obtain particular output signals or sequence of different output
signals. The particular programmed control of audible signal or
alarm device 1 that is used in any given situation will, of course,
depend upon the environment in which the signal device is used and
the signals desired. Thus, not only does audible signal or alarm
device 1 provide a signal device having a multitude of selectable
output signals, but by the addition of a programmable control
device the selection of these outputs can be programmed.
FIG. 3 is a pictorial view showing one way in which the circuit of
FIG. 1 can be fabricated and packaged. As shown in FIG. 3, the
switches SW1, SW2 and SW3 are brought out at each side and the
speaker 15 is mounted under the face plate. This figure is given to
show that while audible signal or alarm device 1 is capable of
providing a strong output signal it can be fabricated into a
compact unit. Printed circuit techniques are used and the resultant
overall unit is very small when compared with conventional sirens,
horns or the like. In fact, a model of the circuit of FIG. 1 has
been manufactured and the overall size of the device, including
batteries, is approximately 5 .times. 2 .times. 2 inches; yet the
output signal is strong enough to be heard at a considerable
distance. The model constructed looks exactly like the device shown
in FIG. 3, except that SW3 was omitted from this model. In this
respect all the switches could be omitted and electronic switches
could be used. Further, the capacitors, variable resistors 10 and
12 could all be housed in the programmable control device rather
than in the signal or alarm device, if such a control device is
used. The specific fabrication used will, of course, be governed by
each particular use of signal or alarm device 1. However, if signal
or alarm device 1 is to be fabricated as a portable device that can
be readily incorporated into any system or used by itself, for
example as an alarm carried by a women in her purse, the
construction shown in FIG. 3 is ideally suitable.
From the foregoing description, it is obvious that this invention
provides a versatile signal or alarm device that is compact,
provides a multiplicity of different signals, and is
self-contained. In addition, the device can be used with a control
device to program the audible signal outputs in accordance with a
predetermined pattern or desired sequence.
While the invention has been described in detail with reference to
a specific embodiment, it will be obvious to one skilled in the art
that various changes and modification, in addition to those
mentioned, can be made without departing from the spirit and scope
of the invention as defined in the claims. For example, any
appropriate oscillator other than unijunction oscillators can be
used for the two oscillator circuits.
* * * * *