US3603985A - Siren-horn circuitry - Google Patents

Siren-horn circuitry Download PDF

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Publication number
US3603985A
US3603985A US826226A US3603985DA US3603985A US 3603985 A US3603985 A US 3603985A US 826226 A US826226 A US 826226A US 3603985D A US3603985D A US 3603985DA US 3603985 A US3603985 A US 3603985A
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transistor
potential
voice coil
producing
collector
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US826226A
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Norman S Goralnick
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B3/00—Audible signalling systems; Audible personal calling systems
    • G08B3/10—Audible signalling systems; Audible personal calling systems using electric transmission; using electromagnetic transmission

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  • Mrose ABSTRACT Variable audiofrequency signals for use in alanns, entertainment devices and like applications requiring sonic outputs from rugged and economical miniaturized equipments which consume little power, are provided by a transistorized circuit wherein sinusoidal outputs from a simple phase-shift oscillator govern the frequencies at which a voltage-controlled audio oscillator drives its load in the form of a voice coil of an inexpensive loudspeaker.
  • the present invention relates to improvements in electronic generation of variable-frequency tones, and, in one particular aspect, to novel and improved miniature electronic sound generators in which unique transistorized circuitry minimizes the electrical power and the number and costs of components required to produce siren-type audio signals.
  • a preferred embodiment utilizes three inexpensive germanium transistors, one of which functions in a first-stage phase-shift oscillator which delivers a low frequency substantially sinusoidal output voltage to a special form of second-stage voltage-controlled oscillator which includes the remaining two transistors.
  • the latter oscillator involves capacitively-coupled feedback which sustains periodic electrical pulse flows through one of its transistors, the pulse repetition rate being in the audiofrequency range and being modulated in repetition rate by the varying voltage delivered by the first-stage phase-shift oscillator.
  • the low-impedance voice coil of a speaker is coupled serially in the current-flow path through the said one of the second-stage transistors, providing a good-quality impedance match directly, and responding to the frequencymodulated current pulses by developing related sonic outputs in the audiofrequency range.
  • Attention-arousing siren characteristics are produced in the described operating mode, despite the obvious lack of sinusoidal characteristics in the pulse signals, and an unvarying hornlike tone, also rich in harmonies, is readily achieved through switched application of a constant-voltage input to the second stage. Power drain from a small battery occurs only on switched command of either the siren or horn tones.
  • an improvedcombination siren-horn network embodying the invention is shown to include first and second transistor circuit stage, 2 and 3, respectively, which are selectably energized via a power source 4, such as that afforded by a conventional 9-volt battery 4a.
  • the network may be commanded to excite an associated loudspeaaker 7 to emit harmonically rich audio tones which automatically ascend and descend in frequency after the fashion of a siren, or, instead, which remain substantially fixed as a constant tone or hornlike sound.
  • Main stage 3 of the network advantageously includes two relatively inexpensive germanium transistors, 8 and 9, which may for example comprise the Types GA3292 and GP2237, respectively, sold by Texas Instruments, Inc.
  • Voltage level at the base of input transistor 8 is affected by the voltage-dividing resistance 10 (example: in association with resistances 11 (150 k) and 12 (560 k), which are serially connected across the source 4 when either switch 5 or 6 is closed.
  • the emitter of transistor 8 is grounded at the negative supply potential, while its collector is connected to the base of the second transistor, 9: the emitter of the latter transistor is connected to the positive side of the supply, and its collector is grounded by way of a loading impedance which is that posed by the voice coil 7a of the loudspeaker 7.
  • Transistors 8 and 9 are arranged as inverting amplifiers, and the capacitor 13 coupling the collector of the second transistor, 9, with the base of the first, 8, occasions the positive feedback which gives rise to desired oscillatory effects in this stage.
  • Capacitor 13 is typically a common 0101 mfd. capacitance for purposes of promoting oscillatory effects in the range of about 200-800 cycles, and, in association with the two' inverting transistors, effectuates the needed phase shift which achieves regeneration.
  • the currents witnessed by voice coil 7a are in pulseTorm. Resulting sonic outputs from speaker 7 are thus well enriched with harmonics, and produce agreeable audio tones rather than harsh noise.
  • Capacitor 13 which initially has zero voltage across it, then commences charging and raising the voltage at the base of transistor 8, the charging rate being determined by the values of the impedances of speaker voice coil 7a and resistances l0 and 11, and by the voltage at the junction of resistances 11 and 12.
  • Capacitor l3 continues to charge until the potential at the base of transistor 8 causes that transistor to conduct, whereupon the potential at the collector of transistor 8 and at the base of transistor 9 is reduced and causes transistor 9 to start to 'turn on.
  • the resulting positive-going potential at the collector of transistor 9 is A-C coupled to the base of transistor 8 through capacitor 13, and this positive-feedback action continues rapidly until both transistors are on hard.”
  • the collector of transistor 9 is clamped at essentially the full battery potential level, and capacitor l3 charges through the low base to emitter saturation resistance of transistor 8, with the result that the potential at the base of transistor 8 begins to fall.
  • the latter potential becomes low enough to start turnoff of transistor 8, whereupon the potential at the collector of transistor 8 and the base of transistor 9 increases and starts turnoff of transistor 9.
  • a negative-going potential then appears at the collector of transistor 9, and is A-C coupled through capacitor 13 to the base of transistor 8, such that both transistors are ultimately full off.
  • the negative; potential resulting at the base of transistor 8 then begins to change positively, at a rate determined by the impedances of voice coil 70, capacitor 13, and resistances l and 1 l, and by the voltage at the junction of 11 and 12, whereupon the cycle repeats.
  • the potential caused to exist at the junction of resistances 11 and 12 has a controlling effect upon the charging rate of capacitor 13, and the latter in turn controls the frequency of the operation of stage 3. As that potential is raised, the charging rate increases and the signals developed through speaker 7 are of higher pitch. Stage 2 varies that potential for purposes of achieving siren tones.
  • stage 3 the uses of NPN transistor 8 and PNP transistor 9 promote the double inversion which is needed to establish the positive feedback condition through capacitor 13.
  • Transistor 8 may therefore be a relatively lowpower unit, while the power rating of transistor 9 is high enough to permit direct coupling of the speaker voice coil to its collector.
  • an astable multivibrator arrangement including collector loads of the usual same value would result in higher power losses than with the improved circuitry. The latter is thus more efficient and insures longer battery life.
  • the effective charge-discharge rate characteristics for feedback capacitor 13 are a function of the voltage appearing at the junction of 11 and 12. So long as this voltage is substantially constant, as it is when pushbutton switch 6 alone is depressed, these characteristics are substantially constant, and the dominant audio tone developed by speaker 7 is essentially fixed; it serves admirably as a horn" tone, for example. There are more commanding attention-getting qualities in a variabletone output, such as the ascending and descending fluctuation of a siren, and, for certain amusement, accessory and alarm application, these fluctuations should be readily produced.
  • Network stage 2 serves such purposes, by delivering a substantially sinusoidal output and tone-control voltage to the aforesaid junction.
  • the frequency-modulating or controlling stage 2 Upon closure actuation of the enabling ganged sections of switch 5, the frequency-modulating or controlling stage 2 is likewise energized by source 4, such that its single common inexpensive transistor 14 (such as the Texas Instruments, Inc. germanium transistor Type GA3292 then has the source voltage applied across the series combination of the load resistance 15 (example: l0 k) and its collector and grounded emitter.
  • source 4 such that its single common inexpensive transistor 14 (such as the Texas Instruments, Inc. germanium transistor Type GA3292 then has the source voltage applied across the series combination of the load resistance 15 (example: l0 k) and its collector and grounded emitter.
  • Stage 2 comprises a form of phase-shift oscillator, in which resistor 16 biases the transistor 14 on, and the phase-shifting ladder network of capacitors l7a-l7c (example: each about 30 mfd.) and resistances 1811-180 (example: each about 30 k) introduces a phase-shift of about 180 between the base and collector of transistor 14 at a predetermined very low frequency, determined by the component valves, which is significantly less than the repetition rate of the pulsing effects in stage 3.
  • the substantially sinusoidal oscillations generated in stage 2 are characterized by related low frequency sinusoidal variation in voltage appearing at the collector of transistor 14, and, therefore, at the switching terminal 5a and junction of resistances 11 and 12.
  • Operation of the network is essentially instantaneous when switch closures take place, and there is no standby power drain, and there is no dissipation of power in the low frequency modulating stage 2 unless the undulating output tones are intended.
  • the illustrated manually operated switches are of course replaced by their automatic counterparts.
  • Electronic tone-producing apparatus comprising a loudspeaker having a voice coil, means producing potential the level of which is related to pitch of tone desired from said speaker, first and second transistors, means interconnecting said transistors in a double inversion amplifying relationship, means directly connecting said voice coil in the current flow path of said second transistor, a capacitance connected to supply positive feedback between the output of said second transistor and the input to said first transistor, and to cause self-sustaining cyclic operations of said transistors, and means applying potential from said potential-producing means to said capacitance in control of the charging and discharging rates thereof, whereby the periodicity of electrical signals through said voice coil and the pitch of tones produced by said speaker are determined by said potential.
  • Electronic tone-producing apparatus comprising a loudspeaker having a voice coil, means producing potential the level of which is related to pitch of tone desired from said speaker, a first NPN transistor, a second PNP transistor, means connecting the collector of said first transistor with the base of said second transistor, means directly connecting said speaker voice coil serially with the collector of said second transistor, a capacitance coupling said collector of said second transistor with the base of said first transistor, means applying to the base of said first transistor potential related to the potential from said potential-producing means, and means for applying potential across the series combination of said voice coil and the emitter-collector path of said second transistor, whereby periodic electrical signals are developed through said voice coil and said speaker produces audio tones determined by said potential level.
  • Electronic tone-producing apparatus comprising a loudspeaker having a voice coil, means producing potential the level of which is related to pitch of tone desired from said loudspeaker, a first NPN transistor, a second PNP transistor, means connecting the collector of said first transistor with the base of said second transistor, means directly connecting said loudspeaker coil serially with the collector of said second transistor, a capacitance coupling said collector of said second transistor with the base of said first transistor, means applying to the base of said first transistor potential related to the potential from said potential-producing means, means for applying potential across the series combination of said voice coil and the emitter-collector path of said second transistor, said means for applying potential across said series combination comprising a battery, positive potential from said battery being applied to the emitter of said second transistor and the collector of said second transistor being connected with the negative-potential side of the battery through said voice coil, and means connecting the emitter of said first transistor with substantially sinusoidally at a frequency which is low relative to frequency of said audio tones, and further comprising switching means for selectably connecting said sinusoidal

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  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
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US826226A 1969-05-20 1969-05-20 Siren-horn circuitry Expired - Lifetime US3603985A (en)

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US82622669A 1969-05-20 1969-05-20

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3707716A (en) * 1970-09-23 1972-12-26 Norman S Goralnick Multi-tone push button controlled electronic horn
US3749838A (en) * 1970-11-30 1973-07-31 J Juba Sound generating device for signaling and responding to nuisance telephone calls
US3938142A (en) * 1973-06-12 1976-02-10 International Standard Electric Corporation Ultrasonic transmitter for the remote control of radio and television receivers

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3440648A (en) * 1968-05-09 1969-04-22 Mallory & Co Inc P R Integrated-circuit amplifier and oscillator
US3493966A (en) * 1967-03-29 1970-02-03 Edwards Co Electronic audible alarm devices having plural oscillators

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS435605Y1 (enrdf_load_stackoverflow) * 1965-05-18 1968-03-12

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3493966A (en) * 1967-03-29 1970-02-03 Edwards Co Electronic audible alarm devices having plural oscillators
US3440648A (en) * 1968-05-09 1969-04-22 Mallory & Co Inc P R Integrated-circuit amplifier and oscillator

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3707716A (en) * 1970-09-23 1972-12-26 Norman S Goralnick Multi-tone push button controlled electronic horn
US3749838A (en) * 1970-11-30 1973-07-31 J Juba Sound generating device for signaling and responding to nuisance telephone calls
US3938142A (en) * 1973-06-12 1976-02-10 International Standard Electric Corporation Ultrasonic transmitter for the remote control of radio and television receivers

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JPS5036759B1 (enrdf_load_stackoverflow) 1975-11-27

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