US2897453A - Sawtooth waveform generators - Google Patents

Sawtooth waveform generators Download PDF

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Publication number
US2897453A
US2897453A US562557A US56255756A US2897453A US 2897453 A US2897453 A US 2897453A US 562557 A US562557 A US 562557A US 56255756 A US56255756 A US 56255756A US 2897453 A US2897453 A US 2897453A
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US
United States
Prior art keywords
valve
capacitor
potential
electrode
diode
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Expired - Lifetime
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US562557A
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English (en)
Inventor
Mansford Hugh Lyon
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EMI Ltd
Electrical and Musical Industries Ltd
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EMI Ltd
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Publication date
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K4/00—Generating pulses having essentially a finite slope or stepped portions
    • H03K4/06—Generating pulses having essentially a finite slope or stepped portions having triangular shape
    • H03K4/08—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape
    • H03K4/10—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only
    • H03K4/12—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth voltage is produced across a capacitor
    • H03K4/20—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth voltage is produced across a capacitor using a tube with negative feedback by capacitor, e.g. Miller integrator

Definitions

  • This invention relates to sawtooth waveform generators.
  • the duration of the return strokes produced by the sweep circuit may sometimes be desirable for the duration of the return strokes produced by the sweep circuit to be variable independently of the duration of the forward strokes, so that a variable delay can be introduced prior to the visible trace produced by the forward strokes, or alternatively so that two vertically spaced traces can be made visible, one corresponding to the forward strokes and the other corresponding to the return strokes.
  • the latter facility may be required for displaying a repetitive signal on two different time scales.
  • One object of the present invention is to produce an improved sawtooth Waveform generator which, though of relatively simple construction, enables the duration of the forward and return strokes to be controlled substantially independently of each other.
  • a sawtooth waveform generator comprising an amplifier, a capacitor, and a switch having one condition in which said capacitor is operative to provide negative feedback from the output electrode to the input electrode of said amplifier to cause the generation of a forward stroke of a sawtooth waveform by integration in said capacitor, and having another condition in which said capacitor is inoperative to provide negative feedback and said amplier is operative to discharge said capacitor to produce a return stroke of said waveform.
  • circuit parameters which control only the functioning of the amplifier during integration that is when acting as a Miller integrator
  • circuit parameters which control only the rate of discharge through the valve can be varied independently.
  • reference 1 denotes a capac- Jr across which, in operation of the circuit the desired ,awtooth Waveform is generated, the waveform being derived from output terminals 2 and 3.
  • the circuit comprises three thermionic valves 4, and 6 which, though shown as triodes, may be pentodes in a practical circuit.
  • the valve 4 functions alternately as the valve of a Miller integrator and as a discharge valve for the capacitor 1, whereas the valves 5 and 6 form part of the switch which conditions the valve 1 for its alternate functions.
  • the valves 5 and 6 are coupled by resistors 7, 8, 9 and to form a conventional bistable D.C. coupled trigger circuit.
  • the resistor 7 is connected to the terminal of a positive H.T. polarising supply.
  • the anode of the valve 5 is connected to the anode of the valve 4 via resistor Patented July 28, 1959 11 and unilaterally conductive device 12, which may be a crystal diode.
  • the capacitor 1 is connected between the anode and control electrode of the valve 4, and the control electrode is connected to the terminal of a negative H.T. supply by an integrating resistor 13, and to a source of negative bias voltage 14, of (say) -10 volts, by a diode valve 15, which may be a crystal diode.
  • the cathode of the valve 4 is connected to the negative H.T. terminal by resistor 16, and to ground by unilaterally conductive device 17, which may be a crystal diode.
  • the control electrode of the valve 5 is connected to the junction of resistors 18 and 19 which are connected from the anode of the valve 4 to the negative HIT. terminal.
  • a cathode follower may be inserted to isolate the load of the resistors 18 and 19 from the capacitor 1.
  • Other cathode followers may also be inserted in the circuits.
  • the circuit is free running and the two phases of each cycle, in which the forward and return strokes of a sawtooth Wave are respectively generated, are controlled by the two conditions of stability of the trigger circuit.
  • the valve 5 is cutolf, and its anode potential is maximally positive.
  • the valve 6 is conducting, taking the common cathode potential of valves 5 and 6 to a higher potential than that at the control electrode of the valve 5.
  • the capacitor 1 charges via resistor 11, diode 12 and resistor 13, the current in the resistor 11 exceeding that in the resistor 13 by the amount of current taken by the valve 4.
  • the valve 4, the capacitor 1 and the associated components function as a self-regulating Miller circuit, the current in the valve 4 varying so as to tend to maintain the charging current for the capacitor 1 constant.
  • the potential at the control electrode of the valve 4 remains above the bias potential 14 so that the diode 15 is non-conducting.
  • the current in the valve 4 is suicient to maintain the diode 17 conducting, maintaning a low cathode-to-ground impedance.
  • the rise in potential at the output terminal 2 due to the charging of the capacitor 1 causes the potential at the control electrode of the valve 5 to rise runtil that valve conducts.
  • valve 5 When the valve 5 conducts, its anode potential falls, and currents in the valve 6 and the diode 12 are cut-off. The potential at the control electrode of the valve 4 then falls until the diode 15 conducts. This fall in potential at the control electrode of 4 is accompanied by an equal change at 2, where a step is produced in the sawtooth waveform. Thereafter, the current is supplied to the resistor 13 only through the diode 15 and the control electrode of the valve 4 is maintained at a fixed potential. This potential brings about such a reduction in the cathode current of the valve 4, that the cathode potential falls and renders the diode 17 non-conducting.
  • the anode of the valve 5, the negative H. T. terminal and the voltage lsource 14, constitute first, second and third points of reference potential for the valve I4.
  • the trigger circuit including the valves 5 and 6 constitutes a switch and in one condition of this switch the diode 12 is conducting and the diode l5 non-conducting ⁇ and in this condition, integration occurs in the capacitor 1 by Miller circuit action.
  • the diode 12 is non-conducting and the diode 15 is conducting thereby tying the input electrode of .the valve 4 to the potential of the third reference point.
  • the valve 4 functions as the conventional discharge valve for the capacitor 1, linearization of the discharge current being achieved by the resistor i6.
  • the constant current conditions during the two phases of a cycle can be varied ⁇ v independently of each other, by varying the values of the resistors 13 and 16, or by varying the potentials at the lower ends of these resistors. If the latter expedient is adapted, means are required for varying the potentials at the lower ends or resistors 13 and 16 independently of each other and of the negativeH. T. supply for other parts of the circuit, which should not be varied. rIherefore the slopes of .the forward and return strokes of the Even in the free running condition of the circuit synchronisation can be achieved by injecting triggering pulses at the cathodes of the valves 5 and 6.
  • the value given to the resistance 11 must be such as to limit the current fed to the anodeA of the valve 4 during the charging phase. This current must exceed that required to charge the capacitor 1 by an amount which can be regulated by the valve 4. Excessive current will overload the valve 4 giving excess charge to the capaci-tor 1. A deiiciency of current will'reduce the current in the valve 4 to a value below that required to keep the diode 17 conducting, and the control of the valve 4 will then ',CeaSe.
  • a switch having one condition in which said unilaterally conductive device is conducting and said capacitor is operative to provide negative feedback from said output electrode to said input electrode thereby to cause the Ageneration of a forward stroke ⁇ of a sawtooth waveform by integration in said capacitor, said switch having another condition in which said unilaterally conductive device is non-conducting and said capacitor is inoperative to provide negative feedback, thereby to cause the generation of a return stroke of said waveform by disgenerated sawtooth waveform can be varied independently. Moreover the duration of a return stroke canbe greater than that of a forward stroke.
  • the second waiting condition is established by bleeding current from the junction of the resistors 8 and 9 to lower the mean control electrode potential of the valve 6. This holds the valve 6 non-conducting even when the discharge of the capacitor l has ceased because the diode l2 is passing current from the anode of the valve 5, the potential at which is limited by the other -added diode (the lower lirnit diode 21). This suspends the cycle at the negative tip of the sawtooth. Triggering of the circuit to give one cycle of operation can then be eected by applying a positive potential excursion to the cathodes ofthe valves 5 and 6, sufficient to turn olf the current in thevalve S.
  • a sawtooth waveform generator comprising an ampliier having an input electrode and an output electrode, first, second and rthird points of reference potential, a path connected from said rst point lto said second point, said path including a rst conductive impedance, a unilaterally conductive device, a capacitor and a second conductive impedance arranged in that order, said output electrode being connected to said path between said unilaterally conductive device and said capacitor and said input electrode being connected to said path between said capacitor and said second conductive impedance, a second unilaterally conductive device connected from said third point n to said path between said capacitor and said second conductive impedance, and a switch for switching the potential at one of said points alternatively between a relatively high value and a lower value, said values being predetermined in relation to the potential at said other points to render the first and second unilaterally conductive devices conducting and non-conducting respectively in a rst condition ot said switch thereby to condition lthe capacitor for negative feedback from said output electrode to said input electrode
  • a generator according to claim 2 said switch comprising two valves each having an input electrode and -an ⁇ output electrode, and means cross-coupling the input and output electrodes to said valves, one end of said path being connected to the output electrode of one of said valves* wherebyv said output electrode constitutes one of said points of reference potential.
  • a generator according to claim 3 further comprising a coupling from the output electrode of said amplitier tofone valve of said switch, whereby transitions of the switch between its two conditions are responsive t0 the potential at the output electrode of said amplifier.
  • a generator according to claim 3 further comprisstroke of the sawtooth waveform, and means for applying triggering signals to induce transitions of said switch between its two conditions.
  • a generator according to claim 2 said amplifier having an electrode common to the input and output electrode circuits of said amplifier, a third conductive mpcdance connected from said common electrode to the second point of reference potential, a fourth point of reference potential and a third unilaterally conductive device connected from said common electrode to said fourth point, the potential at said fourth point being predetermined in relation to the potential at said other points to render the third unilaterally conductive device conducting in the rst condition of the switch to by-pass said third impedance, and to render the third unilaterally conductive device non-conducting in the second condition of the switch to cause said third conductive impedance to provide negative feedback for linearising the discharging current through said amplier.
  • a sawtooth waveform generator comprising an amplifier having an input electrode and an output electrode, a path including a capacitor connected from said output electrode to said input electrode, an integrating impedance for -applying potential to said input electrode, an output impedance for applying potential to said input electrode, and a switch having one condition in which said impedances are enabled to cause the generation of one stroke of a sawtooth waveform by integration in said capacitor,
  • a sawtooth waveform generator comprising an ampliiier having an input electrode, an output electrode and an electrode common to the input and output circuits of said amplier, a path including a capacitor connected from said output electrode to said input electrode, an integrating impedance for applying potential to said input electrode, an output impedance for applying potential t0 said output electrode, and a feedback impedance for applying potential to said common electrode, a switch having one condition for shunting said feedback impedance and for enabling said integrating and output impedances to cause the generation of one stroke of a sawtooth waveform by integration in said capacitor, and having another condition for disabling said integrating and output impedances for integration and for conditioning the capacitor for discharge through said amplifier linearised vby said feedback impedance.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Generation Of Surge Voltage And Current (AREA)
  • Dc-Dc Converters (AREA)
US562557A 1955-02-03 1956-01-31 Sawtooth waveform generators Expired - Lifetime US2897453A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3176/55A GB823370A (en) 1955-02-03 1955-02-03 Improvements relating to sawtooth waveform generators

Publications (1)

Publication Number Publication Date
US2897453A true US2897453A (en) 1959-07-28

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US562557A Expired - Lifetime US2897453A (en) 1955-02-03 1956-01-31 Sawtooth waveform generators

Country Status (5)

Country Link
US (1) US2897453A (enrdf_load_stackoverflow)
DE (1) DE1043542B (enrdf_load_stackoverflow)
FR (1) FR1159579A (enrdf_load_stackoverflow)
GB (1) GB823370A (enrdf_load_stackoverflow)
NL (2) NL100416C (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2984788A (en) * 1959-11-12 1961-05-16 Rca Corp Sweep circuit
US3031628A (en) * 1958-03-26 1962-04-24 Texas Instruments Inc Transistor oscillator
US3049627A (en) * 1957-06-17 1962-08-14 Martin Marietta Corp Electrical timing circuit
US3050686A (en) * 1959-02-12 1962-08-21 Korff Marvin Direct coupled bootstrap sawtooth generator
US3231761A (en) * 1962-02-09 1966-01-25 Siemens Ag Albis Precise timing circuit with linear charge network
US3256446A (en) * 1960-11-23 1966-06-14 Ferguson Radio Corp Linearly-varying output voltage generation utilizing a transistorized, modified, miller integrator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1115291B (de) 1956-04-03 1961-10-19 Servomex Controls Ltd Elektrischer Impuls- und Wellengenerator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3049627A (en) * 1957-06-17 1962-08-14 Martin Marietta Corp Electrical timing circuit
US3031628A (en) * 1958-03-26 1962-04-24 Texas Instruments Inc Transistor oscillator
US3050686A (en) * 1959-02-12 1962-08-21 Korff Marvin Direct coupled bootstrap sawtooth generator
US2984788A (en) * 1959-11-12 1961-05-16 Rca Corp Sweep circuit
US3256446A (en) * 1960-11-23 1966-06-14 Ferguson Radio Corp Linearly-varying output voltage generation utilizing a transistorized, modified, miller integrator
US3231761A (en) * 1962-02-09 1966-01-25 Siemens Ag Albis Precise timing circuit with linear charge network

Also Published As

Publication number Publication date
FR1159579A (fr) 1958-06-30
NL100416C (enrdf_load_stackoverflow)
NL204110A (enrdf_load_stackoverflow)
GB823370A (en) 1959-11-11
DE1043542B (de) 1958-11-13

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