US3218621A

US3218621A - Electronic annunciator improvements

Info

Publication number: US3218621A
Application number: US49670A
Authority: US
Inventors: George E Foster
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-08-15
Filing date: 1960-08-15
Publication date: 1965-11-16
Anticipated expiration: 1982-11-16

Description

Nov. 16, 1955 G. E. FOSTER ELECTRONIC ANNUNCIATOR IMPROVEMENTS Filed Aug. 15. 1960 LIGHT OFF SOUND -OFF F LASH L\GHT FLASH [SOUND-BUZZ 4 Sheets-Sheet 1 UGHT- FLASH SOUND HORN ALARM" L\G HT 5TB ADV SOUND-OFF -FJL g; 2 ANNUNCJATOR 200 2,

SUPERVISORY /40 FLASHER cmcurr 400 l 300 0 401ZL 400A 1 SOUNDER L 4005 5,1 4 4oa i -49o fJI 3 429 L@ 425 OR 420 405 408 428 Kj mam 4/4 AND I 427 l l 424 OR 4/5 435 31 fgf 4o7 4:2 402 359 39 5 AND 426 500 INVENTOR. GEORGE. E. FOSTER 4/1 490 MEM BY 425 F gm pmwl Nov. 16, 1965 G. E. FOSTER 3,218,621

ELECTRONIC ANNUNCIATOR IMPROVEMENTS Filed Aug. 15, 1960 4 Sheets-Sheet 2 FROM OTHER SUPERVISORY CIRCUITS TO OTHER SUPERVISOR! Q22 CJRCLHTS FROM 402 FLASHER SOUNDER 500 TO LOUD SPEAKER INVENTOR. GEORGE E. FOSTER Nov. 16, 1965 e. E. FOSTER 3,218,621

ELECTRONIC ANNUNCIATOR IMPROVEMENTS Filed Aug. 15. 1960 4 Sheets-Sheet 3 625A 1 6 601A o 690 0A SUPERVlSORY ClRCUlT 600 i i-I -O SOUNDER Ll Q- 7 TO SOUNDER C 0&0 AND OTHER SUPERWSORY 70/ 7/0 cmcuws l c4o INVENTOR. GEORGE E. Fos-r ER 3,21 &1

Nov. 16, 1965 G. E. FOSTER ELECTRONIC ANNUNCIATOR IMPROVEMENTS 4 Sheets-Sheet 4 Filed Aug. 15, 1960 INVENTOR. GEORGE E. FOSTER BY 31 PM W WW EUDZ DOW OP NQQ mm-IwdJ u EON-u mwIkO ZONE H mwDZDOm OP um l lu United States Patent 3,218,621 ELECTRONIC ANNUNCIATOR MPROVEMENTS George E. Foster, 7917 S. Yale, Chicago, Ill. Filed Aug. 15, 1960, Ser. No. 49,670 2 Claims. (Cl. 340-2132) This invention relates in general to annunciators and more particularly to improvements in an annunciator system of the type disclosed in application No. 9,925 filed February 19, 1960 by the applicant herein.

This application is therefore a continuation-in-part of the aforementioned application, wherein an annunciator arrangement was disclosed comprising a number of electronic gate or supervisory circuits for monitoring respective locations and arranged to control a common sounder circuit. On receiving a signal indicating a trouble or fault condition from a respective location each supervisory circuit signalled an elert condition to an attendant by flashing a lamp individual thereto and operating the common sounder circuit to provide an audible signal indicating an alert condition. It will be understood that the use of the terms fault or trouble are used herein merely to in dicate a departure from normal and that they are primarily illustrative of the most frequent type of use for annunciators in detecting apparatus malfunctioning, but that the annunciator arrangements described herein are capable of being used in numerous types of call systems.

The alert condition could be irreversible and therefore regardless of the nature of the fault condition the annunciator remained in the alert condition, until the attendant acknowledged occurrence of the signal by operating an acknowledgment key which placed the circuits in a certain condition. When the trouble condition was cleared, a signal resulted that enabled the supervisory circuit to again operate the sounder and flash the lamp which informed the attendant of this condition known as the flash condition. He then again acknowledged by operating the key to reset the equipment in a normal condition. If, while the annunciator was in the flash condition, the trouble or fault condition should reoccur, the attendant might not be informed of this, without performing an acknowledgment operation. In addition, the common sounder was operated in the same manner responsive to either the alert or flash conditions, so that the attendant was not automatically informed of the difierence in the two conditions or states.

The circuits disclosed in that application, however, represented a considerable forward step in annunciator systems in that they utilized solid state elements in an unusually economical design. Previously annunciators had incorporated standard relay components which suffer from a number of disadvantages including the likelihood of the inoperability, when needed, due to such causes as contact corrosion or burning, but until the arrangement disclosed in the forementioned application was devised it was economically unfeasible to supplant relays with solid state elements. This was most likely due to the conception that a solid state element must ordinarily be provided for each movable contact set provided in a relay system, and as the solid state elements are considerably more expensive than contact sets, the cost of such an installation would be considerable.

In the present invention several novel annunciator circuit arrangements are provided utilizing solid state elements in circuits having similar advantages to those disclosed in the aforementioned application. These circuits are arranged to permit the annunciator to signal a reversion of a fault to normal when in the alert condition and to signal a reversion to a fault when in the flash condition. Further, the common sounder and supervisory circuits 3,218,621 Patented Nov. 16, 1965 ice incorporate novel economical circuit designs which permit the sounder to be operated in distinctively indicating modes when indicating an initial trouble or alert condition and when indicating the clearing of the trouble or a flash condition. This automatically informs the attendant whether the annunciator is in the alert or flash condition. Further improvement resides in adapting certain of the circuits described in the aforementioned application for operation with the sounder illustrated herein to provide the advantageous results described.

It is therefore an object of the present invention to provide an electronic annunciator of improved versatility..

It is another object of this invention to provide a sound control arrangement for an annunciator that is capable of providing a plurality of difierent sounds each signalling a different annunciator condition.

It is still another object of this invention to provide a monitoring or supervisory circuit for use in an annunciator to reversibly control the annunciator signalling sequence.

It is an additional object of this invention to provide a supervisory circuit such as described that may be used to operate with different types of sound control equipment.

It is still a further object of this invention to provide an electronic annunciator system having a signalling sequence including signals of difierent types of which one type has precedence over a signal of another type.

It is yet another object of this invention to provide a signal arrangement in an electronic annunciator that functions to provide sound signals of different types responsive to diiferent conditions of the annunciator.

It is yet a further object of this invention to provide in an annunciator having a plurality of diiferent conditions, signals each individual to a different condition and to provide means for terminating one of said signals and operating another irrespective of the condition of said annunciator.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel circuits and features and a combination of parts hereinafter fully described, illustrated in the accompanying drawing, and particularly pointed out in the appended claims it being understood that various changes in the form and minor details of the circuits and apparatus may be made without departing from the spirit or sacrificing any of the advantages of the invention.

For the purpose of facilitating an understanding of this invention, there is illustrated in the accompanying drawing a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, this invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawing in which the same reference characters are employed wherever possible to indicate corresponding or similar parts throughout the several figures of the drawing:

FIG. -1 is a diagrammatic illustration of the operative sequence. of the annunciator to be described in connection with FIGS. 2, 3, 4 and 5.

FIG. 2 is 'a block diagram of the annunciator whose operative sequence is shown in FIG. 1.

FIG. 3 is a block diagram of one of the supervisory circuits shown in FIG. 2 and shown in detail in FIG. 4.

FIG. 4 illustrates the circuit details of one of the supervisory circuits contained in the block diagram in FIG. 2.

FIG. 5 illustrates the circuit details of the sounder shown in the block diagram in FIG. 2.

FIGS. 6 and 7 are simplified supervisory circuit arrangements for use in an annunciator having a slightly different operative sequence from the annunciator shown in FIG. 1; and

FIG. 8 is a supervisory circuit for monitoring a plurality of different locations and utilizing an operative sequence such as disclosed in the aforementioned application but arranged for operation with a sounder of the type disclosed herein.

Referring now to FIGS. 1 and 2 it will be noted that the annunciator designated 200 in FIG. 2 may be in any one of the four condtiions indicated in FIG. 1. That is, it may be in either normal, alert, alarm or flash condi tions. Each of these conditions represents a different state of one or more of the

supervisory circuits

400, 400A and 400B forming part of the annunciator 200. Each supervisory circuit 400, 490A and 4008 monitors at least one location for a trouble or fault signal. The monitored locations are individual to the various supervisory circuits and each represents a remote point or location at which various apparatus may be located. When the monitored apparatus is functioning normally, this apparatus is arranged to provide an electrical signal of one type to its respective supervisory circuit. Such type of signal may include a signal of no aflirmative polarity, if the monitored apparatus is not functioning properly it is arranged to transmit a signal of different character to its respective supervisory circuit. Such a transmitted signal may be one of a defined polarity or it may be one of a polarity opposite to that of the above noted one type.

Thus, if all the monitored location points are functioning normally, the annunciator 200 is in normal condition; namely, neither light nor sound is provided. The light or sound, just referred to, means a light or sound other than normal status light or sound. If one or more of the monitored locations develops a fault or trouble, at corresponding signal is transmitted to the respective

supervisory circuit

400, 400A or 400B. The supervisory circuit then controls the annunciator 200 to indicate the alert condition by a respectively associated flashing lamp 475 and by operating the common sounder 500. This sounder thus provides a horn or warble sound. Hence, an attendant at the annunciator station is informed of the alert condition. He is informed too of the origin or location of the fault or trouble.

In the diagram of FIG. 1, the alert condition is reversible. This reversibility is indicated by the double arrow heads on the line 100 between the normal and alert conditions. Thus, if the trouble condition should be temporary and should be cleared, the annunciator 200 reverts back to the normal condition. The flashing light and horn or warble sound indicating the alert condition are thus automatically turned off.

The attendant, on having his attention called to the alert condition by the sound and the flashing light, performs an acknowledgment operation. This operation comprises operating a key. This operation places the annunciator 200 in an alarm condition indicated by an absence of sound and a steady light at the supervisory circuit. The alarm condition is irreversible for any location at which the trouble developed. This irreversibility is indicated by the line 110 with the single arrowhead pointing towards the alarm condition. Thus the operator has acknowledged the trouble and has placed the annunciator 200 in the alarm condition. In this fashion the annunciator in this specific embodiment of the invention maintains a record of the existence of trouble at a specific monitored location by the steady light. At the same time the operator is undisturbed by the continuance of the unpleasant alarm sound.

If, during the alarm condition, another monitored location should develop trouble, a new'signal is transmitted to its supervisory circuit. This new signal controls the annunciator 200 to provide an alert condition. This immediately informs the attendant of the newly developed trouble. Upon this occurrence, the attendant will normally, again perform the acknowledgment operation with 4 the result that the alarm sound is stilled but a dual trouble light indication exists.

In some situations the attendant is aware that the described sequence has resulted, not from a true malfunction, but from the fact that certain equipment at the monitored location has intentionally operated to an unusual condition. For example, a furnace which may require considerable time to cool may have been shut down. The attendant knows that, under these circumstances, although an alert condition is indicated, no trouble is actually involved. He therefore merely acknowledges as described and waits. Normally, however, if the alert annunciator condition results from a true trouble condition, the attendant acknowledges as described and takes the steps to remedy the defect. The annunciator 2% therefore remains in the alarm condition pending the removal of the trouble or the return of the equipment into its functioning condition.

At the time the trouble is removed, the input to the respective supervisory circuit returns to normal and the supervisory circuit controls an appropriate indicating signal. The supervisory circuit now controls the annunciator 200 to indicate the flash condition. As noted heretofore, in this condition the light associated with the supervisory circuit flashes and a buzzing sound indication is provided. As this flash situation may result from just the temporary correction of an indicated fault, apparatus in accordance with the invention provides a reversible operation between flash and alarm conditions. This reversibility is indicated by the double arrowheads associated with here as indicated by the line 120. Thus if a fault is only temporarily or intermittently eliminated, the annunciator 200 reverts to the alarm condition. If, however, the fault is fully eliminated the annunciator 200 stays in the flash condition. This latter situation indicates to the attendant that the trouble condition has been cleared. It will benoted that the flash condition is readily distinguished from the alert condition by a difference in sound. This flash condition is distinguished from the alarm condition with equal ease by the fact that'the lamp 475 lights intermittently or flashes. With the attendant informed that the trouble is corrected, he simply operates the acknowledgment apparatus to return the annunicator 200 to normal condition. This irreversible transfer from flash to normal annunciator conditions is indicated by the single arrowhead associated with the line 130. The light and sound are now both off. It will be understood, of

course, that the acknowledgment operation, while anysupervisory circuit is in the alarm condition, will have no effect on that circuit and the indicating light remains continuously on.

With this operational functioning of the annunciator 200 in mind, attention now is invited to FIG. 2 which shows the annunciator 200 in block form. It will be seen that the annunciator comprises a number of supervisory circuits indicated at 400, 400A and 400B each having a respective indicating light 475, 475A and 475B. Each supervisory circuit is connected to monitor an individual location over a lead such as 401. The number of supervisory circuits corresponds to the number of remote locations to be monitored. Each supervisory circuit may, however, monitor a number of such locations as will be seen hereafter in connection with the description of the structures of FIG. 8. In addition, the annunciator comprises a common flasher circuit at 300 and a sounder circuit 500. The flasher is substantially similar to the flasher circuit shown in my aforementioned application. It is clear, however, this flasher 300 may be any of many other well known circuit arrangements for furnishing alternate pulses of suitable potential over lead 402.

The supervisory circuits each comprise circuitry responsive to trouble signals appearing on an associated monitoring lead, e.g., lead 401, for operating the common sounder 500. Each supervisory circuit is arranged to control the sounder 500 in accordance with the various monitored circuits and annunciator conditions. This control is exercised by way of

leads

404 and 405. The sounder 500 comprises novel arrangements amenable which to common control by all the plural supervisory circuits to establish the required sound patterns under control of any one supervisory circuit. It will be appreciated, of course, that under certain circumstances the sounder described in my aforementioned application may also be used with the supervisory circuit 400, etc.

The acknowledgement operation is signalled over lead 403 by means of key 490. This key, in this embodiment of the invention, is shown connected in common to all the plural supervisory circuits. It is clear to those skilled in the art that, for particular monitoring functions, connection to selected circuits of the plurality may be advantageous.

In FIG. 3 a block diagram illustrating the logical progression of operations performed in a supervisory circuit is provided. With the supervisory circuit 400 in a normal condition, the lamp 475 is extinguished and no operating signal appears on either lead 404 or 405 extending to the common sounder 500. Flasher circuit 300 lead 402 is pulsed with alternative signals of different potential values. A signal of one such potential value is used as an operating signal. These alternatively valued pulses are extended over lead 402 both to the supervisory circuit 400 and to the sounder 500 as seen in FIG. 2. Clearly, with reference to FIG. 2, as this pulse signal is applied to circuit 400, so this flasher signal is applied to the other lines of the plural supervisory circuits.

At the supervisory circuit 400 the alternative signals from the flasher are extended through the OR gate indicated at 427 to conductor 413 and the AND gate indicated at 428. As the supervisory circuit is in the normal condition, no corresponding signal appears on conductor 414 the AND gate 428 blocks the flasher signal from lead 406 extending to lamp 475. The lamp 475 therefore remains extinguished. It will be noted in FIG. 3 that various conductors are connected by dashed lines to indicate the connections are extended through either isolating resistors, rectifiers, transistors, or other circuit components for performing necessary functions that will be more clearly apparent from the later detailed description of the supervisory circuit 400.

Assuming now that the location monitored by the supervisory circuit 400 develops trouble so that a corresponding signal appears on lead 401 extending to the gate circuit indicated at 420. The gate circuit 420 responds to the incoming trouble signal to provide an appropriate output over

leads

407 and 408. The output over lead 407 is extended to an AND gate 425, and, as will be seen in connection with FIGS. 4 and 5, to memory circuit 423. Similarly the inverted signal appearing on 1 lead 408 is re-inverted by the amplifier 409 as seen in connection with the following discussion of FIGS. 4 and 5. This so inverted signal is similarly applied to the memory 423.

The output signal extending over lead 408 is extended through the gate circuit 424 to lead 409. From lead 409 it is extended to an AND gate 426 which is presently closed due to the output on lead 410. The output on lead 409 is also extended to the OR circuit 429. The OR circuit 429 provides an output over lead 414 to the AND gate 428. Lead 402 is in the meantime pulsed by alternate signals from the flasher 300. During alternate periods when conductor 402 is pulsed from the flasher 300, these signals are transmitted through OR gate 427 to the AND gate 428 over lead 413. The AND gate 428 is therefore periodically energized by flasher signals over lead 413, and signals from OR gate 429 if an appropriate signal is supplied to that latter OR gate, therefore provides a signal for intermittently flashing the lamp 475 over lead 406. With the lamp flashing and the horn or warble signal provided through the sounder 500, the

6 attendant is alerted by the annunciator 200 and is informed of the trouble location.

If the trouble condition should clear, of course, the signal is removed from lead 401 and the circuit 420 returns to its original state. The operating signal is therefore removed from

leads

407 and 408. The AND gate 425 therefore blocks any output to conductor 405 to terminate operation of the sounder 500 and quiet the horn or warble noise or sound. Similarly, of course, the OR gate 429 provides no operating signal to the AND gate 428 and this prevents the flasher signal from intermittently lighting the lamp 475.

Assuming now that the trouble condition was not selfcorrecting or was not eliminated, before the attendant operates the acknowledgment key 490. On operation of the key 490, a signal is provided over lead 403. This signal switches the memory 423. The memory 423 now removes an operating signal from lead 411 to close the AND gate 425. This terminates the signal over lead 405 to the sounder 500 and operation of the horn is discontinued. Simultaneously, the memory 423 provides an output signal over lead 410 to the AND

gates

426 and 435 and to the OR gate 429. As lead 409 is now providing an appropriate output and lead 410 has an appropriate potential, the AND gate 426 provides a continous or steady output signal of a desired character over lead 412 to the OR circuit 427. The OR circuit 427 now provides this steady signal to the AND gate 428 and, as the OR circuit 429 is also providing a steady signal to lead 414 from both the output on lead 409 and from lead 410, the AND gate 428 provides a steady output over lead 406 to the lamp 475. The lamp 475 therefore remains continuously lighted. With the lamp 475 continuously lighted, and the sounder 500 quiescent, the attendant knows that the annunciator 200 is in the alarm condition.

If now, another location should develop a trouble situation, the circuit corresponding to 420 at the respective supervisory circuit 400A, for example, provides an output over lead 406A, analogous to 406 discussed above, and 405 as described. The output over lead 405 from the AND gate corresponding to 425 at supervisory circuit 400A causes the sounder circuit 500 to again provide the horn or warble sound. Similarly, the lamp, for example, lamp 475A as supervisory circuit 400A is also flashed in a manner described. The attendant is alerted to a trouble condition at a different location. He therefore again operates the acknowledgment key 490 to place the annunciator 200 in the alarm condition with the lamp 475A continuously lighted and the horn oif under control of sounder 500.

If, after the annunciator is in the alarm condition, the trouble is cleared, the fault signal provided, illustratively, over lead 401 is removed. The circuit 420 at the respective supervisory circuit 400 therefore returns to its original condition. The leads 407 and 408 therefore also revert to their original condition. AND gate 425 remains closed, while lead 409 also reverts to its original condition under control of circuit 424. This closes AND gate 426 and opens AND gate 435. With AND gate 435 open, lead 404 extending to the sounder 1500 is provided with an appropriate output so that sounder 500 provides a buzz sound which is in the nature of a steady hum. That sound indicates to the attendant that a trouble condition is cleared. With AND gate 426 closed, the steady signal to

gates

427 and 428 is removed, leaving the alternate signals from lead 402 in control of these gates. As lead 410 also applies its output to OR circuit 429, the AND gate 428 is intermittently opened in response to signals from flasher 300, and the lamp 475 is intermittently lighted. This informs the attendant, which circuit has been cleared.

If now the trouble condition should reoccur, the output on lead 409 reverts to indicate the trouble by clos ing the AND gate 435 and terminating further operation of the sounder 500 while opening AND gate 426 so that the lamp 475 returns to a steady lighted condition.

Assuming that the trouble condition remains clear, the attendant acknowledges the same by operating the acknowledgment key 490 again. On doing so, he resets the memory 423 to restore the original output to leads 410 and 411. He thereby extinguishes the lamp 475 by removing the signal from OR gate 429 and restores the sounder 500 by closing AND gate 435 to remove the operating signal from lead 404. As lead 401 is restored to its original condition, supervisory circuit 400 is prepared for another cycle.

The detailed circuit arrangement of the supervisory circuit 400 and the sounder 500 may be seen by reference to FIGS. 4 and respectively. Taking first FIG. 4 wherein the supervisory circuit 400 is shown with the various circuits discussed in conjunction with FIG. 3 indicated by dashed lines, it will be noted that the input to lead 401 is connected through a transformer 440, whose primary is connected across a signalling circuit controlled from the remote monitored location either through appropriate switching circuits or directly. It will also be noted that a test circuit is indicated at terminal 415 Whose function is simply to permit the simulation of a fault or trouble signal to determine that the components are functioning properly. The trouble signal may be provided by the closure of a contact set across the primary of transformer 440; however, this condition is primarily one of choice and may on the contrary be provided by the interruption of a normally present signal which may be either A0 or DC. depending on the needs of the circuit. The diodes or rectifiers D1 and D2 are connected across opposite ends of the secondary of transformer 440 to provide a negative potential via lead 401 to the base circuit of transistor Q1 responsive to the occurrence of a trouble signal across the transformer primary. Condenser C1 ensures that the signal is a true fault signal and not just a transient condition resulting from various noise conditions.

Normally, transistor Q1 is off so that conductor 407 is somewhat above the negative potential indicated at C1 and conductor 407 is below the positive potential indicated at +31. The negtaive potentials provided in the system are indicated by the character C1 or C2, while the positive potentials are indicated by the reference character +B1. Potentials lying between these two values are provided by appropriate resistance drops connecting the same and a selected reference or neutral potenial, which may if desired be at ground, are indicated by i.

When the trouble signal occurs, condenser C1 is charged negatively as this condenser becomes sufficiently charged, the base circuit of transistor Q1 is biased to initiate conduction. That is, Q1 goes from an OFF to an ON condition. As a result of this conduction condition shift, the collector circuit of transistor Q1 swings toward neutral potential in response to its turning on and

conductors

407 and 408 therefore become considerably more positive. With the positive signal applied to conductor 408, normally on transistor Q2 turns off so that conductor 409 swings negative.

Conductor 407 on swinging towards a more positive potential transmits that potential to the emitter circuit of normally olf transistor Q3. As the base circuit of transistor Q3 is biased negative by the potential on lead 411, that transistor Q3 turns on to transmit a positive signal across the diode D3 to lead 405 extending to the sounder 500. This will turn on the horn to provide an alert signal as will be described in conjunction with the description of sounder circuit 500.

When conductor 400 swings toward negative potential, conductor 414 also assumes a more negative potential determined by the drop across resistor R6. Conductor 414 transmits the corresponding negative signal to the base circuit for transistor Q4. In the meantime, lead 402 alternates between negative and more positive potentials under control of the flasher 300, and when lead 413 swings, negative to follow the potential on lead 402, both transistors Q5 and Q4 turn on in tnadem. Transistors Q5 and Q4 will therefore come on intermittently following the potential swings on lead 402. With transistor Q4 on, a negative voltage swing is coupled to the base electrode of power transistor Q6. Thus, Q6 is turned on. The light 475 is therefore intermittently lighted over lead 406 as transistor Q6 follows the intermittent conduction of Q4 and Q5 to inform the attendant which circuit had developed the alert condition.

It will be appreciated, of course, if the trouble condition is alleviated long enough to enable condenser C1 to assume a normal charge state, i.e. a charge to the potential +131, that transistor Q1 turns otf.

Leads

407 and 408 revert to their original or normal condition and transistors Q2 and Q3 do the same. As transistor Q2 turns on, conductor 414 swings positive to shut off transistor Q4 and thus to terminate flashing of the light 475. At the same time, the turning off of transistor Q3 terminates operation of the sounder 500. The annunciator 200 therefore reverts to normal and the attendant need take no action unless it is necessary to trace the cause of the temporary fault signal.

The attendant noting the alert condition (assuming the annunciator 200 remains in that condition) now operates the acknowledgement key 490 and applies a substantial negative potential over lead 403 and resistor R15 to the base circuit of normally olf transistor O7 to turn that transistor on. A similar potential is applied to resistor R18. With lead 407 connected to the other side of resistor R18 through diode D4, however, that other side remains clamped to the neutral potential on lead 407. With transistor Q7 on, transistor Q8 turns off. As the collector circuit of transistor Q7 swings positive, lead 411 swings in the same direction to turn transistor Q3 off and terminate the signal on lead 405. This cuts off the horn or warble sound provided by the sounder 500.

As transistor Q8 turns off, a substantial negative potential is transmitted over lead 410 to

conductors

412 and 414. The latter conductor, of course, is already negative due to the negative potential on lead 409. The negative swing on lead 410 is also transmitted to the base circuit of transistor Q9; however, as the emitter circuit of transistor Q9 is held negative by the potential on lead 409, that transistor Q9 does not turn on, as yet.

With conductor 412 swinging negative, conductor 413 also swings negatively to establish a negative potential on the base circuit of transistor Q5. Thus transistors Q5, Q4 and Q6 are continuously conducting without regard to the signals supplied over lead 402 by the flasher. The light 475 is now continuously energized. Since the horn is olf by virtue of termination of the signal on lead 405. There is thus established the alarm condition for the annunciator 200. Further operation of the acknowledgment key 490 will have no further effect as Q8 cannot be turned on thereby.

In this alarm situation, the indicated circuit defect may be eliminated. Thus the fault indicating signal is removed from lead 401. The transistor Q1 turns off and transistor Q2 turns on; therefore lead 407 swings in a negative direction, however transistor Q3 is already off.

When transistor Q2 turns on, lead 409 swings towards a positive value and the same is applied the emitter circuit transistor Q9. The positive potential on lead 409 is also transmitted through diode D6 to clamp lead 412 positive. With lead 410 at a negative value, transistor Q9 initiates conduction to apply a positive signal over lead 404. This positive signal operates the sounder 500 to provide a steady buzz tone. This tone informs the operator that the ammunciator condition has been changed from the alarm condition to a flash condition.

With lead 412 clamped at the same potential as lead 409, lead 413 can swing negative only when the flasher provides appropriate signals over lead 402. As lead 410 is still negative, the potential on lead 414 is at a corresponding value and transistors Q4 and Q5 conduct in response to the flasher signals to flash lamp 475. On noticing the flashing condition of the lamp 475 and the steady hum, the attendant is informed that the trouble condition has been alleviated and knows the annunciator 200 is in the flash condition.

If the trouble signal should now reappear, transistor Q1 again conducts to cut off Q2. Lead 409 is shifted to a negative value and conductor 412 again swings negative. Transistors Q4, Q5 and Q6 again conduct continuously to maintain lamp 475 continuously lighted. With lead 409 negative, transistor Q9 cuts on to terminate the signal on lead 404 and shut off the sounder 500. With sounder 500 off and lamp 475 lighted continuously, the annunciator 200 has reverted to the alarm condition so that the attendant is accordingly signalled.

The attendant again momentarily operates the acknowledgment key 490 if the annunciator stays in the flash condition to apply a substantial negative potential through resistor R18 to the base circuit of transistor Q8. This potential turns transistor Q3 on. This transistor Q8 is turned on by operation of key 490 since no fault exists and transistor Q1 is off. Thus lead 407 is now negative to eliminate the clamp through diode D4 on the base circuit of transistor Q3. Diode D5, of course, maintains one end of resistor R15 at the positive potential of lead 409 to prevent the negative potential on lead 403 from being applied to the base circuit of Q7. Transistors Q7 and Q8 are now in their normal or original condition.

Transistor Q8 on turning on, removes the negative potential from lead 410 and the potential on that lead swings positive. Hence conductor 414 is now maintained at a potential which holds transistors Q4, Q5 and Q6 cut oif. The annunciator 200 is now in the normal condition and is prepared for another cycle.

Referring now to FIG. 5 showing the details of the sounder 500, it will be seen that it is connected in common to each

supervisory circuit

400, 400A and 400B by means of two separate input leads 404 and 405 and is provided with pulses of alternate potential over lead 402 from the flasher 300. Lead 405 is connected to the base circuit of normally on transistor Q20 and lead 404 is connected to the base circuit of normally on transistor Q21. Transistors Q20 and Q21 each control a multivibrator circuit arrangement comprising the transistors Q24 and Q25 which feed the transformer 550. Transformer 550, in turn, feeds the amplifiers Q26 and Q27, which power a loud speaker (not shown) over transformer 560. The multi-vibrator is normally unoperated unless controlled by transistors Q20 or Q21 in response to a signal transmitted over either leads 404 or 405 respectively and when operated provides a frequency corresponding to the transistor initiating its operation.

Several unusual features are incorporated in this circuit whereby the flasher signals over lead 402 are applied to intermittently turn the multi-vibrator on under control of transistor Q20 so that the sound of constantly varying or intermittent intensity is derived, while a simple feed-back circuit connected between Q20 and Q21 permits signals on lead 405 to override signals on lead 404, thereby ensuring that the alert sound is provided in prefer ence to any other.

It will be recalled that when a trouble situation occurred that set the annunciator 200 in the alert condition by the flashing lamp 475 that a horn signal resulted from the signal over lead 405. The signal over lead 405 comprises a positive swing as transistor Q3 turns on and this causes the base circuit of transistor Q20 to swing positive. Transistor Q20 therefore turns off. It will be noted at this time that if transistor Q21 were oif the negative swing in the collector circuit of transistor Q20 is applied to the base circuit of transistor Q21 through resistor R40, and transistor Q21 is turned on. In any event, this negative bias is held on the base circuit of transistor Q21 so that a signal on lead 404 cannot turn Q21 oil. This arrangement gives the alert signal, the horn signal controlled by lead 405, precedence and prevents interference therewith by a signal indicating a flash condition of the annunicator 200.

Presuming now that transistor Q20 is turned oil? by a positive signal on lead 405, its collector circuit swings negative. A corresponding potential swing is transmitted through resistors R40 and R45 respectively causing the base circuit of transistors Q21 and Q22 to follow that swing. Both transistors Q21 and Q22, therefore, turn on, or, if on, remain on. Transistor Q22 turns on through a circuit including alternately conducting multi-tvibrator transistors Q24 and Q25. The transistors Q24 and Q25 turn on and olf at a rate determined by the RC circuits connected thereto. Included in these circuits is the low resistance R50.

In the on condition, the transistor Q21 collector circuit is positive. Thus this circuit acts to bias the base circuit of transistor Q23 off. Hence, as transistor Q21 conducts, transistor Q23 is ofl except when negative signals appear on lead 402 from the flasher 300. At that time transistor Q23 conducts through resistors R50 and R55 and transistor Q22. As transistor Q23 conducts through the voltage divider comprising resistor R50, the frequency of the multivibrator is changed. As transistor Q23 is conducting only intermittently under the influence of flasher 300, the signal output to transformer 550, to transistors Q26 and Q27 and to transformer 560 to the speaker is at a constantly varying frequency. This varying frequency causes the speaker to emit an audible horn or warble signal of demanding and alerting character.

The attendants subsequent operation of the acknowledgment key 490 turns off transistor Q3 at the supervisory circuit to remove the signal from lead 405. Transistor Q20 therefore turns on; however, the bias on the base circuit of transistor Q21 does not change sufliciently to turn this latter transistor off. The positive swing transmitted through resistor R45, however, does turn oif transistor Q22 to prevent further conduction through any of the transistors Q23, Q24 and Q25. Accordingly, the sound is terminated and the annunciator 200 is in the alarm condition. If now another supervisory circuit such as 400A should transmit an alert signal over lead 405, the procedure for providing the warble sound is repeated.

Assuming now that a flash conditon has occurred and that transistor Q9 at the supervisory circuit is conducting to transmit a positive signal over lead 404. The end of resistor R34 connected to the base circuit of transistor Q21 swings positive to turn transistor Q21 off. The collector circuit of Q21 therefore swings negative to bias the base circuits of both transistors Q22 and Q23 negative and each turns on. Transistor Q23 now remains on continuously without regard to the positive swings on lead 402, as the base circuit of transistor Q23 is biased negative by the collector circuit potential of Q21. With transistors Q22 and Q23 conducting continuously, transistors Q24 and Q25 alternately conduct. This alternate conduction provides an alternating output through

transformers

550 and 560 for operating the loud speaker to provide a steady buzz sound indicating the flash condition.

If during the flash condition a signal should appear on lead 405 indicating an alert condition, transistor Q20 turns off to turn Q21 on, as explained. The flasher signal on lead 402 now controls Q23 so that it conducts alternately to provide the alert signal from the loud speaker as explained. Likewise if the flash condition should revert to an alarm condition transistor Q9 turns 0E. This removes the signal from lead 404 and transistor Q21 turns on. This 11 cuts olf transistors Q22, Q23, Q24 and Q25 and the sound is terminated while the annunicator reverts to the alarm condition.

With the sounder 500 controlled to indicate the fiash condition, acknowledgment key 490 is operated to turn transistor Q9 off at the supervisory circuit. This cuts on the signal on lead 404. Transistor Q21 then turns on. When Q21 turns on, of course Q22 is biased oil and further loud speaker operation is terminated. The annunciator is now at normal and the cycle may now be repeated.

In the annunciator arrangement shown in FIG. 6 a simplified supervisory circuit 600 is provided for accomplishing certain purposes of the present invention. This circuit is illustrative of an arrangement adapted to operate a variant sounder indicated by the box 650. This sounder is similar in character to that shown in the aforementioned application instead of to the sounder just described. The operation of that described sounder, however, may easily be accommodated with the instant supervisory circuit. The sounder 650 is also under control of plural supervisory circuits 600A and 60013, each of which,

is provided with an incoming lead 601A and 601B respectively for receiving trouble signals and these circuits are similar to supervisory circuit 600. In addition, the acknowledgment key 690 is provided. This key transmits a timed acknowledgment signal to the supervisory circuits and to sounder 650 in a manner similar to that explained in the aforementioned application. If desired, of course, a separate key may be provided for each supervisory circuit.

Condenser C8 may be either connected to the base circuit of transistor Q50 as indicated by the dashed connection or to the collector circuit of transistor Q50 and the base circuit of transistor Q51 as indicated by the starred connection. This condenser C8 is adapted to charge on signals of considerably shorter duration than that contemplated for condenser C1 in FIG. 4. If condenser C8 is connected to the base of transistor Q50, the collector circuit of transistor Q50 is connected to C1 potential as indicated by the dashed line therebetween.

In the one charging path, a resistor R100 is shown connected between the base and collector circuits of transistors Q50 and Q51 respectively to provide an extremely simple arrangement for holding Q50 and Q51 in a desired condition as will be explained.

It will be noted that the sounder 650 is operated through a condenser C25 and diode D25 instead of through the transistors Q3 and Q9 as shown in FIG. 4. Thus instead of providing both the horn or warble sound and the steady tone as described in the aforementioned application, only a steady tone is provided. Also, as no flasher circuit input is provided to the

supervisory circuits

600, 600A or 6003, the indicating lights shown at 625, 625A and 625B are continuously lighted when signalling.

Assuming first the connection of condenser C8 to the base circuit of Q50 and the use of resistor R100, it will be seen that a negative fault signal appearing on lead 601, switches transistor Q50 on. Transistor Q50 may also be switched on for a simulated trouble signal applied at test terminal 609 for testing the operative sequence of the supervisory circuit.

The positive swing occurring in the collector circuit of transistor Q50 is transmitted to the base circuit of transister Q51 to turn Q51 01f. As the collector circuit of Q51 swings negative, this potential is transmitted through resistors R100 and R110 respectively. The negative potential transmitted through resistor R100 will maintain Q50 on regardless of the removal of the trouble signal on lead ,601 as resistor R100 is considerably smaller than resistor R105. The signal transmitted through R110 of course turns transistor Q52 on so that its emitter circuit swingsnegative, and its collector circuit positive.

As the emitter circuit of Q52 swings negative, amplifier transistor Q53 switches on to light lamp 625 so that the attendant knows the location of the trouble. Capacitor C25 now also charges in a direction corresponding to the positive potential swing in the collector circuit of Q52 to thereby transmit a pulse through diode D25 for operating the sounder circuit 650. Thus the associated loud speaker emits a tone as described in the aforementioned application.

It will be noted that if the trouble signal is now removed from lead 601, transistor Q50 is maintained conductive due to the negative potential transmitted through resistor R100. If resistor R is not used, of course Q50 would turn off in response to removal of the fault signal, thereby causing Q51 to conduct and terminate operation of Q52 and lamp 625. The sounder 650 remains on, however, in either case as the signal to the sounder 650 trips a memory therein which retains the sounder operated until the acknowledgment key 690 is operated, as explained in the aforementioned application. As in one case, however, the light turns off, the attendant knows that the trouble is alleviated.

The acknowledgment key 690 on operation provides a negative signal to the base circuit of transistor Q51 to turn this transistor on. As the collector circuit of Q51 swings positive, Q50 and Q52 turn off. As the acknowledgment signal is applied for a predetermined time in any well known manner of application Q51 will remain on only for that period, if the trouble signal is not removed. If the trouble signal is not removed, transistor Q50 turns back on as soon as the acknowledgment signal is removed and the lamps 625 relight as explained. If transistor Q52 is only turned off momentarily, capacitor C25 does not recharge sufficiently to enable the subsequent conduction through Q52 to result in the transmission of a pulse through D25 to operate the sounder 650. The sounder 650 is turned off on operation of the acknowledgment key 690 through the ganged switch provided therefor, however any other switch arrangements are possible. No sound is therefore provided after the acknowledgment operation.

With the lamps 625 remaining lighted, the attendant knows the alarm condition is maintained. He therefore periodically operates the key 690 to determine if the trouble signal is removed in the event resistor R100 is provided. If the trouble signal has been removed, transistor Q50 remains otf following the acknowledgment signal and Q51 remains on. If resistor R100 is not provided, of course, as soon as the trouble signal is relieved Q50 turns off and Q51 turns on. In either event Q51 turning on causes Q52 to remain off and extinguish lamps 625. Thereafter the supervisory circuit 600 is prepared for another cycle.

When the starred connection from lead 601 to the base circuit of transistor Q51 is provided, transistor Q51 is normally maintained on by a negative signal and is turned off responsive to the removal of the negative signal indieating a fault. On turning off transistor Q51, the collector circuit of this transistor swings negative so that the base-emitter circuit of transistor Q50 conducts. The lamp 625 and the sounder 650 are operated as before described, and the attendant operates the acknowledgment key 690 to terminate operation of the sounder 650.

In the arrangement shown in FIG. 7, a simpler version of the supervisory circuit shown in FIG. 6 is illustrated. This circuit is also intended to operate with a sounder such as 650 described in the aforementioned application.

In this case the input is connected from lead 701 directly to normally otf transistor Q60. This transistor switches on, as soon as capacitor C40 is charged sufiiciently by a negative fault or trouble signal. Likewise transistor Q60 may be switched on by a simulated fault signal applied at test terminal 709. Amplifier transistor Q61 therefore also switches on to light the lamp 710, while the pulse provided by transistor Q60 is transmitted over capacitor C45 and over diode D60 thus to operate the sounder 650 to provide the alerting tone. The attendant subsequently acknowledges by turning ofi the sounder as described in the aforementioned application, but lamp 710 remains lighted as long as transistor Q60 is Assuming that the trouble signal is thereafter terminated for a sufiicient period to permit capacitor C40 to discharge, transistor Q60 turns off. This in turn switches Q61 off and extinguishes the lamp 710 so that the attendant knows the trouble is alleviated.

In FIG. 8 another form of a supervisory circuit for use in accomplishing certain of the purposes of the present invention is illustrated. With this arrangement, three dilferent lamp circuits are provided for each supervisory circuit. Each lamp circuit is utilized to signal a fault at a different location. Also the circuit shown in FIG. 8 incorporates certain features of the type of supervisory circuit shown in the aforementioned application in that it utilizes a memory comprising transistor Q85 and Q86 and alternate signals over lead 802 from a flasher circuit but arranged to operate with a sounder such as sounder 500 illustrated in FIG. 5.

Thus normally separate inputs from respective locations are provided at leads 801, 801A and 8013 while terminal 809 is used to apply a simulated fault signal for test purposes. Transistors Q80, Q90 and Q95 connected to the respective input leads are normally 01? as are respectively associated lamps, red lamp 810, green lamp 810A and amber lamp 810B. The lamp colors are, of course, a matter of choice. Each lamp is associated with an individual supervisory circuit. The lamps, further, each emit a different color so that each monitored location associated with the supervisory circuit may be identified.

Responsive to a trouble signal at one of the monitored locations, for example, a trouble signal at that location associated with lead 801, transistor Q80 initiates cond-uction. This conduction biases the base and emitter circuits of transistors Q81 and Q88 respectively in a positive direction. Transistor 81 therefore turns ofi and, as its collector circuit swings negative, a corresponding pulse is applied over lead 822 to the respective base circuit of transistors Q83 and Q85. Transistor Q85 begins to conduct and its collector circuit swings positive to render transistor Q86 nonconductive. With transistor Q86 off, its collector circuit swings negative to transmit a corresponding pulse to the base circuit of transistor Q88 to turn Q88 on.

Transistors Q83 and Q84 now also conduct in tandem responsive to intermittent or alternate signals over lead 802 from the flasher. The base circuit of amplifier transistor Q89 therefore swings negative when Q83 and Q84 come on and it intermittently lights the red lamp 810.

Fault signals appearing at either leads 801A or 801B apply a negative signal at the base circuit of respective transistors Q90 and Q95. Each therefore also conducts to turn respective amplifier transistors Q91 and Q96 on respectively. When this occurs the respective green and

amber lamps

810A and 810B light to signal the fault condition to the attendant.

When the base circuit of transistor Q88 swings negative, this transistor turns on to transmit a positive pulse to the sounder over lead 805. This lead corresponds to lead 405 described in connection with sounder 500. The pulse over lead 805 has substantially the same effect as described for sounder 500 in causing the sounder to provide a warble tone indicating the alert condition of the annunciator.

The attendant responds to this condition by operating the acknowledgment key 890 to transmit a negative pulse over lead 803. This pulse turns transistor Q86 on. The conduction of this transistor, in turn, terminates conduction by transistor Q85. As the collector circuit of now conducting transistor Q86 swings positive, this swing cuts off transistor Q88 to terminate the war-ble sound. The negative swing in the collector circuit of transistor Q85 14 is now transmitted to the base circuit of Q84 so that transistors Q83 and Q84 now conduct continuously to maintain lamp 810 continuously lighted.

If now, the trouble signal should be corrected, conduction through transistor Q is terminated and transistor Q81 turns on. As the collector circuit of Q81 swings positive, a corresponding pulse is transmitted to the base circuit of transistor Q86 over lead 822 to turn Q86 off and Q on. As Q85 comes on, the emitter circuit of Q87 is biased positive, while the base circuit of Q87 is biased negative from the collector circuit of cut off transistor Q80. Transistor Q87 therefore switches on to transmit a positive pulse over lead 804 to the sounder. This positive pulse has the same elfect as a positive pulse described over lead 404 in causing the sounder to emit a steady tone or hum. In the meantime the negative swing in the collector circuit of Q86 is transmitted to the base circuit of Q83. At the same time, alternate flasher signals are applied to the base circuit of Q84. Transistors Q83 and Q84 therefore conduct in tandem. Thus current flows intermittently to light lamp 810.

The attendant is now informed of the fiash condition and operates the acknowledgment key again to apply a signal over 803 for turning Q86 on. When this occurs Q85 goes off to bias the emitter circuit of Q87 negative and to turn this latter transistor off. This terminates the signal over lead 804 and the sounder now reverts to the quiescent state. The positive swing in the collector circuit of transistor Q86 is transmitted to the base circuit of Q83. Since the collector circuit of Q81 is positive, this terminates further conduction through transistors Q83 and Q84 to maintain lamp 810 off. The supervisory circuit is now ready for another cycle.

From the preceding description of the invention it will be appreciated that the same represents a considerable improvement in facilitating the utilization of electronic annunciators, however, it is believed that the invention is not limited to the particular embodiment or arrangement shown herein, but that its concepts are more fully set forth in the appended claims.

I claim:

1. A sound control circuit for use in an annunciator wherein a plurality of normally inoperative circuits is provided for receiving respective fault signals, the improvement comprising a normally conductive first transistor connected in common with each of said plurality of normally inoperative circuits, a current generator arranged to generate a current of any one of a number of frequencies, a second normally conductive transistor connected in common with each of said plurality of circuits, means operated for rendering said first transistor nonconductive responsive to the receipt of a fault signal by any one of said plurality of circuits, means thereafter controlled for operating said generator to generate current at a predetermined first frequency for operating a signal at a corresponding frequency, means for rendering said second transistor nonconductive responsive to the disappearance of a fault signal to operate said generator to generate current at second frequency to operate a signal at said second frequency, and means controlled by said first nonconductive transistor for maintaining said second transistor conductive irrespective of the disappearance of a fault signal at another one of said plurality of circuits.

2. The arrangement claimed in claim 1 in which said maintaining means comprises an OR gate connected between said first nonconductive and said second conductive transistors.

References Cited by the Examiner UNITED STATES PATENTS 2,600,132 6/1952 Seaton 340--213 2,659,07-1 1-1/1953 Dohm 340-329 2,695,400 11/1954 Snitjer 3402l3 2,709,249 5/1955 Sperry 340-213 (Other references on following page) 1 5 UNITED STATES PATENTS Marmorstone 340--213 Ross 340213 Warren 340--213 Rodgers 340213 5 Ebel 340-213 Beguin 340-213 Keller 340-213 Vitt et a1 340-2132 Noreen et a1 340213.2 1O

Brown et a1. Transistors: A New Class of Relays, in Control Engineering, Dec. 1956, pp. 70-76.

NEIL C. READ, Primary Examiner. BENNETT G. MILLER, Examiner.

Claims

1. A SOUND CONTROL CIRCUIT FOR USE IN AN ANNUNICATOR WHEREIN A PLURALITY OF NORMALLY INOPERATIVE CIRCUITS IS PROVIDED FOR RECEIVING RESPECTIVE FAULT SIGNALS, THE IMPROVEMENT COMPRISING A NORMALLY CONDUCTIVE FIRST TRANSISTOR CONNECTED IN COMMON WITH EACH OF SAID PLURALITY OF NORMALLY INOPERATIVE CIRCUITS, A CURRENT GENERATOR ARRANGED TO GENERATE A CURRENT OF ANY ONE OF A NUMBER OF FREQUENCIES, A SECOND NORMALLY CONDUCTIVE TRANSISTOR CONNECTED IN COMMON WITH EACH OF SAID PLURALITY OF CIRCUITS, MEANS OPERATED FOR RENDERING SAID FIRST TRANSISTOR NONCONDUCTIVE RESPONSIVE TO THE RECEIPT OF A FAULT SIGNAL BY ANY ONE OF SAID PLURALITY OF CIRCUITS, MEANS THEREAFTER CONTROLLED FOR OPERATING SAID GENERATOR TO GENERATE CURRENT AT A PREDETERMINED FIRST FREQUENCY FOR OPERATING A SIGNAL AT A CORRESPONDING FREQUENCY, MEANS FOR RENDERING SAID SECOND TRANSISTOR NONCONDUCTIVE RESPONSIVE TO THE DISAPPEARANCE OF A FAULT SIGNAL TO OPERATE SAID GENERATOR TO GENERATE CURRENT AT SECOND FREQUENCY TO OPERATE A SIGNAL AT SAID SECOND FREQUENCY, AND MEANS CONTROLLED BY SAID FIRST NONCONDUCTIVE TRANSISTOR FOR MAINTAINING SAID SECOND TRANSISTOR CONDUCTIVE IRRESPECTIVE OF THE DISAPPEARANCE OF A FAULT SIGNAL AT ANOTHER ONE OF SAID PLURALITY OF CIRCUITS.