US3476865A - Variable time delay multivibrators - Google Patents
Variable time delay multivibrators Download PDFInfo
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- US3476865A US3476865A US601790A US3476865DA US3476865A US 3476865 A US3476865 A US 3476865A US 601790 A US601790 A US 601790A US 3476865D A US3476865D A US 3476865DA US 3476865 A US3476865 A US 3476865A
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- delay
- multivibrator
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- voltage
- random
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10H—ELECTROPHONIC MUSICAL INSTRUMENTS; INSTRUMENTS IN WHICH THE TONES ARE GENERATED BY ELECTROMECHANICAL MEANS OR ELECTRONIC GENERATORS, OR IN WHICH THE TONES ARE SYNTHESISED FROM A DATA STORE
- G10H1/00—Details of electrophonic musical instruments
- G10H1/02—Means for controlling the tone frequencies, e.g. attack or decay; Means for producing special musical effects, e.g. vibratos or glissandos
- G10H1/04—Means for controlling the tone frequencies, e.g. attack or decay; Means for producing special musical effects, e.g. vibratos or glissandos by additional modulation
- G10H1/043—Continuous modulation
Definitions
- the present invention pertains in part to relaxation 4 Claims oscillators of the multivibrator type wherein the time period within which the device remains in a particular state is rendered variable by varying one or more operating parameters of the device, and in part to electronic musical instruments wherein such devices are used in the tone generating apparatus to randomize the phasing of"- the output tones; 7
- monostable or one-shot multivibrators are characterized by a stableoperating state and a quasi-stable operating state, transition from the former to the latter being triggered by an external signal, usually a pulse or spike, termed a trigger or set pulse, whereas retum transition to the reset state or condition (i.e. back to the stable state) occurs spontaneously after a fixed time interval, without the aid of an external-signal.
- the device is often used to produce a pulse upon elapse of a*fixed time interval following the transmission of a first pulse (the trigger) so as to effect a'- desired delay; hence it'is commonly referred to 'as a delay multivibrator. Since the delay depends to a great extent on component values and types and/or on the magnitude of the bias voltages applied to the multivibrator," it is possible to preselect any desired delay period, within practical limits,
- a monostable multivibrator whose delay period, i.e. interval during-which the device remains in its quasi-stable state, varies'in random fashion. More specifically, it is an object of the invention to provide a monostablemultivibrator-whose delay time "is controlled by a source of randomly varying voltage to appropriately 'excitatory circuits for random perturbation of triggerable or switchable devices, i.e. devices which may be forced to undergo a transition from one state'to another.
- Anapplication of the present'invention resides, for
- the 'basic tone generators are typically continuously running, i.e'., are functioning at all times, so that a note in any octave may be produced upon depression or actuation of the appropriate key.
- a noise controlled delay multivibrator comprises a pulse generator triggerable from a stable operating state to a quasi-stable state, returning to the stable state after a time delaydepending on the time constant of the generator circuit and the instantaneous level of bias voltage on an active element of the generator.
- the bias voltage level is controlled by the output of a noise source.
- the present invention also provides in a frequency divider or multiplier chain for production of tones associated with octavely related notes, excitatory circuits for supplying random perturbation of each divider or multiplier, each excitatory circuit including a noise controlled delay multivibrator of the type mentioned briefly above, and each divider of the chain comprising, for example, a flip-flop which is triggered from one stable state tion of the following flip-flop the divider sequence or chain; "Each delay multivibrator is set, i.e.
- each delay multivibrator is transferred to the flip-flop under its control and so on through the chain, the uncertainty in the delay variations of successive delay multivibrators increasing by a factor equal or substantially equal to the division factor of the chain, provided the same or substantially the same amount of noise voltage is used for each delay multivibrator.
- This difi'ers from the case in which a random fluctuation is initially derived and this fluctuation simply transferred through the chain, in which case there is no random phasing of the output of each divider.
- the randomness of the trigger for each flip-flop, and hence 3 of theoutputof the flip-flop differs for each flip-flop in the chain while the uncertainty of the delay variations of successive delay multivibrators is a function of the dividing (or multiplying) factor of the chain.
- FIGURE 1 is a schematic diagram of an electronic tube version of a monostable multivibrator incorporat those components.
- FIGURE 4 is a schematic diagram of a solid state embodiment of a portion of the circuit of FIGURE 2, incorporating a transistorized version of a noise-controlled delay multivibrator.
- FIGURE 1 there is shown a cathodecoupled monostable or one-shot multivibrator of conventional form except in respect to certain structural and operational features in accordance with the present invention, as will be discussed in detail in the ensuing description.
- the circuit comprises a pair of vacuum tubes 15 and 20 (or two distinct tubes in a single envelope,
- the grid of tube 20 is also coupled to the supply voltage in a manner to be described presently.
- tube 15 Prior to receipt of a trigger pulse or positive-going step wave at terminal 10, tube 15 is cut off and tube 20 is conducting, by virtue of the DC bias voltage level on the grid of the former and the eifectively clamped grid of the latter.
- a positive-going trigger pulse applied to terminal 10 is differentiated by low time constant RC (differentiator) network 12 comprising series capacitor 13 and shunt resistor 14, to provide a synchronizing pulse at the grid of tube 15 that renders the latter conductive. Consequently, the grid of tube 20 is driven highly negative relative to its cathode, and tube 20 is cut ofi. This is the situation characterizing the quasi-stable state of the delay multivibrator.
- noise generator 25 i.e., a source of noise voltage
- the multivibrator In the absence of noise generator 25, (i.e., a source of noise voltage) the multivibrator returns to its stable state when the voltage at the grid of tube 20, which rises exponentially at a rate determined primarily by the RC time constant, imposed by resistor 18 and capacitor 19,
- noise source 25 is inserted between the grid of tube 20 and the source of supply voltage.
- the voltage at node or point 27 of the circuit is thus the algebraic sum of the supply voltage and the noise voltage, and undergoes random variation in either direction from the voltage level E
- the time interval required for termination of the quasi-stable state is less than that which would occur if grid voltage were determined by E alone, whereas for voltage levels less than E the delay is greater.
- the noise output of source 25 consistsof random fluctuations (for a random noise source), it will be apparent that the delay (time between set and reset of the multivibrator) also varies in a random fashion following application of each trigger pulse to the multivibrator.
- the output of the multivibrator is a pulse whose width corresponds to the random time interval during which the multivibrator is in its quasi-stable state.
- variable voltage source i.e., a source of voltage whose output level may be controllably varied
- noise source 25 if it is desired toset or control the time delay in predetermined fashion.
- the time delay need not remain fixed but can vary from a minimum to a maximum value, and vice versa, in a progressive manner, or may undergo discrete variations in a selected sequence, according to the type of control exercised. Random variation of delay, however, is particularly advantageous in certain situations, as will be explained presently in conjunction with the exemplary problem of faithfully imitating the sounds of a conventional pipe organ, complete to random phasing and rushing air noise, with an electronic organ.
- a source of random voltage fluctuations will vary between practical voltage limits according to the type of noise source used. Moreover, the fluctuations need not be random in the absolute sense, but may be obtained from a conventional pseudorandom sequence (convertible to voltage) generator.
- the voltage range of the variable voltage source and the values of the circuit elements establishing the time constant for response of the switching elements of the multivibrator are selected to assure a time delay no greater than the time between successive trigger pulses. This, in turn, assures synchronization of the output pulses (start) with the trigger pulses.
- a divider chain whichmay be used for tone generation in an electric organ, comprising a basic tone generator ormaster oscillator 40 which may, for example, simply bean astable multivibrator square wave generator, followed by successive noise-controlled delay multivibrator of the type described above and frequency divider (divide-by-two circuit) such as 46, 45-1, 47, 45-2, and so forth, depending upon the number of frequency divisions desired.
- Each frequency divider may be of any conventional type, such as a flip-flop, although it is to be understood that the invention is not to be limited to division by two, nor to square wave generation.
- An output may be taken from master oscillator 40 and from each of the dividers to provide octavely related tones, each output also being provided to the next component in the chain, e.g., from master oscillator 40 to noise-controlled delay multivibrator 46.
- FIGURE 3 illustrates the timing of the waveforms obtained at the output terminals of each of the components of the divider chain of FIGURE 2.
- the wave shapes illustrated in FIGURE 3 have been idealized to zero rise and fall times and no overshoot or undershoot.
- the output of tone generator 40 is a series of square waves 50 (FIGURE 3w) repeating, for example, at a frequency of 1760 c.p.s.
- Noise-controlled delay multivibrator 46 is set, that is, switched from a stable to its quasi-stable state, each time a positive-going wave is applied thereto, and resets over a randomly variable time interval having illustrative limits indicated by the crosshatched area at the end of each pulse of the waveform 51 (FIGURE 3b), the output of multivibrator 46.
- the random time interval is determined by the amount of noise voltage present and reset may be arranged to occur sometime after a specified portion of a period of the input wave 50.
- the average frequency of the output Waveform of delay multivibrator 46 or any of the succeedin components is unaltered. Referring to waveform 51, for example, it may occur that the first output pulse from delay multivibrator 46 terminates at a time indicated by the start of the cross-hatched area, whereas the second pulse terminuates at a time indicated by the end of the crosshatched area. The third pulse may terminate at a point in time within the cross-hatched area, and so on in random manner. The average frequency is unaffected because an output pulse is generated each and every time a positive-going input pulse 50 is applied to the multivibrator.
- Each divided-by-two circuit 45-1 through 45-n changes state upon application of a negative-going voltage step thereto.
- the delay perturbation of the preceding noise-controlled delay multivibrator is transferred to the flip-fl0p that it controls.
- the delay perturbations of multivibrator 46 are transferred to flipfiop 45-1.
- the result is the output waveform 52 of divider 45-1, shown in FIGURE 3(0).
- the pulse is characterized by a randomness of starting time as well as of termination time. Again, while the Width of individual pulses will vary, the average frequency remains fixed.
- the positive-going portion of each pulse generated by divider 45-1 is utilized to trigger the next delay multivibrator 47 to its quasi-stable state, and so forth.
- the noise-controlled delay multivibrator is a collector-coupled one shot circuit, analogous to a platecoupled tube type monostable multi.
- transistor 72 is on and transistor 70 is off.
- Pulses applied to input terminal 60 from the master oscillator (not shown) are differentiated and the negative-going trigger resulting from each differentiation is passed by diode 75 for application to the collector of transistor 70 and the base of transistor 72. If base drive is desired a positive trigger is instead applied to the base electrode of transistor 70.
- the multivibrator then undergoes a transition to the quasi-stable state, in which transistor 70 goes on and transistor 72 goes off, and remains in that state until transistor 72 comes out of cutoff. This occurs when the base voltage of transistor 72 overcomes the cutoff bias, over a period of time determined by the charging of capacitor 77 through resistor 78, and by the random fluctuations of noise source 80.
- the random duration negative-going output pulses of the monostable multivibrator are applied to conventional bistable multivibrator 85 via coupling capacitor -87 and diodes 88 and 89. Since flip-flop 85 is conventional it need not be further described or discussed. It is sufficient to note that the output of this divider (flip-flop 85) is a randomly phased pulse train at half the average frequency of the output of the master oscillator.
- noise source for the delay multivibrator need not be located as shown in FIGURE 1 for a tube circuit nor as shown in FIGURE 4 for a transistor circuit, but may be placed in any convenient location in the circuit such that it will have the desired effect on the control electrode bias voltage for the second element (e.g., tube or transistor) of the multivibrator.
- noise generator may instead be connected to the emitter of transistor 72 and, via a resistance, to the base of that transistor.
- FIG- UR-ES 1 and 4 are for the sake of illustration and clarity only, being those used in construction embodiments of the invention but certainly subject to variation or complete change according to established techniques of circuit design in conjunction with the teachings presented herein.
- FIGURES 2 and 4 fall within the terminology multiplier chains since division is in fact multiplication by an inverse number.
- a tone generator for an electric organ comprising:
- noise controlled delay multivibrator coupled in cascade with said stable oscillator and arranged to have rises synchronized with said square wave outputs and falls which are random about an average value in response to said noise
- noise controlled delay multivibrators each include a pair of transistors interconnected in a monostable configuration, and wherein each of said configurations includes a first transistor responsive to a synchronizing signal and 7 8 having a collector and a second transistor coupled to said 4.
- each fi st translstor we a tuning capacltor and havmg a base, of said delay devices includes a random noise controlled sa1d timlng capacitor being connected from said collector delay multivibrator having delays randomly varying about t sai base, a constant average delay value.
- n 5 i References Cited a random voltage noise source connected in series with said source of steady DC supply voltage and said UNITED STATES PATENTS timing resistance to said base, to provide a trigger 3,147,334 9/1964 White 84-1.04 X voltage at said base which has a random comp n n 10 3,260,864 7/1966 Nourney 307-173 3.
- a tone generator for an electronic organ comprising a frequency divider chain having cascaded flip-flop JOHN S. HEYMAN, Primary Examiner divider elements,
- a separate random delay device coupled between each US pair of said divider elements, said delay devices each 15 84 1 05 11; 307.424 273; 328 '..51; 331 73 providing delays smaller than the period of the divider element during that delay device.
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Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US60179066A | 1966-12-14 | 1966-12-14 |
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US3476865A true US3476865A (en) | 1969-11-04 |
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US601790A Expired - Lifetime US3476865A (en) | 1966-12-14 | 1966-12-14 | Variable time delay multivibrators |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3590131A (en) * | 1969-02-11 | 1971-06-29 | Robert R Reyers | Electronic musical scale generator employing a single master oscillator |
US3867862A (en) * | 1973-06-11 | 1975-02-25 | Baldwin Co D H | Electrical musical instrument |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3147334A (en) * | 1955-09-28 | 1964-09-01 | White James Paul | Device for altering tone quality in electronic musical instrument or the like |
US3260864A (en) * | 1964-09-01 | 1966-07-12 | Hewlett Packard Co | Variable delay time pulse generator |
-
1966
- 1966-12-14 US US601790A patent/US3476865A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3147334A (en) * | 1955-09-28 | 1964-09-01 | White James Paul | Device for altering tone quality in electronic musical instrument or the like |
US3260864A (en) * | 1964-09-01 | 1966-07-12 | Hewlett Packard Co | Variable delay time pulse generator |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3590131A (en) * | 1969-02-11 | 1971-06-29 | Robert R Reyers | Electronic musical scale generator employing a single master oscillator |
US3867862A (en) * | 1973-06-11 | 1975-02-25 | Baldwin Co D H | Electrical musical instrument |
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Owner name: GENERAL ELECTRIC CREDIT CORPORATION, A NY CORP., C Free format text: SECURITY INTEREST;ASSIGNOR:BPO ACQUISITION CORP., A DE CORP;REEL/FRAME:004297/0802 Effective date: 19840615 Owner name: SECURITY PACIFIC BUSINESS CREDIT INC., 10089 WILLO Free format text: SECURITY INTEREST;ASSIGNOR:BPO ACQUISITION CORP. A CORP OF DE;REEL/FRAME:004298/0001 Effective date: 19840615 |
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