Showing papers on "Relaxation oscillator published in 1968"

Temperature control circuit

Abstract: A temperature control circuit for accurately controlling the temperature of a medium includes a bridge which senses the temperature of the medium. The bridge supplies a signal representative of the temperature difference between the desired temperature and the actual temperature of the medium to a differential amplifier. A network coupled to the differential amplifier provides a visual indication of the temperature difference and amplifies the signal received from the differential amplifier. A relaxation oscillator network is coupled to the network to operate a triac. The triac controls a heater and thus regulates the temperature of the medium.

Control apparatus for electric automotive vehicles

Abstract: 1,267,421. Control of D.C. motors. GULTON INDUSTRIES Inc. 8 April, 1969 [5 April, 1968], No. 17842/69. Heading H2J. In a battery powered vehicle, regenerative braking down to a low speed is facilitated by a voltage boosting circuit 33 connected to the motor 4, and a shunt field 4C is connected, for braking, to the otherwise series-wound motor. The boosting circuit comprises an inductor 35 connected between the positive armature terminal and the battery via a diode 40 and switched periodically by thyristors 43, 44 and 47, 48 with a commutating capacitor 41. The thyristors are fired in alternate pairs by a circuit 45 which comprises a relaxation oscillator and bi-stable circuit (Fig. 3, not shown), the frequency of the oscillator and hence the amount of braking being adjustedby a brake pedal controlled rheostat 26. In an alternative arrangement (Fig. 6, not shown) the average current through the inductor is kept constant for a given pedal setting by an operational amplifier which adjusts the frequency of the oscillator according to the volt-drop across a resistor in series with the inductor. The brake pedal also controls a rheostat 29 in the shunt field circuit and a mechanical brake 22 through a lost-motion link so that it is effective only in the final stage of braking. Change-over from driving to braking is effected by a relay K1 energized by first movement of the brake pedal. The speed of the motor during driving is controlled by a thyristor 6 having a turn off circuit 10 which comprises two pairs of auxiliary thyristors and a commutating capacitor (Fig. 4, not shown) which are fired in alternate pairs by a square-wave generator. Triggering pulses for 6 are produced by a relaxation oscillator and unijunction circuit whose operation is synchronized with the square wave generator, the firing instant and hence pulse width being controlled by an accelerator operated rheostat in the oscillator circuit. Some shunt field current is provided through resistor 5 to prevent runaway on no load.

Control circuits for electromagnetic clutch-brake driving devices

Abstract: A circuit which does not require mechanical relays is disclosed using silicon-controlled rectifiers (SCR''s) for controlling manually and/or automatically the starting and stopping of a clutch-brake motor having an electromagnetically actuated clutch and brake. Each clutch turnoff brake winding is connected to a source of full wave rectified AC voltage through its own SCR and selective turnoff is effected by capacitor commutation. Momentary overexcitation of both windings is provided by alternative initial discharge therethrough of energy previously stored in respective capacitors. These capacitors are charged through separate individual SCR''s from an AC voltage of a value higher than the normal DC energizing voltage used for continuously exciting the coils. The four SCR''s are turned on in pairs, one SCR of each pair closes a circuit connecting the respective winding to the previously charged capacitor and thereafter to the normal DC energizing bus. Diode gates prevent adverse interaction between the capacitors and the DC bus and provide properly timed energy flow from the DC bus to the winding as soon as the capacitor voltage drops to a value slightly below the bus voltage so that there is no discontinuity in the winding excitation. The trigger pulse which turns on one SCR to energize one winding also turns on the other SCR of the pair, which latter SCR connects the capacitor for charging or storing energy which is later released for initially energizing the other winding. A no-voltage release circuit employs a unijunction transistor (UJT) as a relaxation oscillator connected to a DC supply having a large capacitor. This oscillator provides triggering pulses to the gate of the SCR which controls excitation of the brake winding. Normally, however, with full line voltage, a transistor base-biased to saturation, has its emitter-collector circuit connected across the timing capacitor of the UJT oscillator, thus normally shorting the capacitor and preventing oscillation. Upon failure of line voltage, the transistor turns off due to loss of base bias and the timing capacitor charges from the energy in the large capacitor, and the oscillator supplies a triggering pulse to the SCR for energizing the brake coil. The voltage of the previously charged capacitor now connected to the brake winding will, even in the absence of line voltage, supply a high impulse of energy to the brake coil to bring the load quickly to standstill.

Large amplitude operation of the nonlinear oscillator

Abstract: A two-parameter oscillator equation is obtained from the inverse tangent approximation to the amplifier function. The equation accounts for the exponential wave shape of relaxation oscillations, which cannot be explained by van der Pol's equation.

Power pack for photographic flashlamp

Abstract: A POWER PACK FOR A PHOTOGRAPHIC FLASHLAMP HAVING A STORAGE CAPACITOR INCLUDES A BATTERY AND CONTROL CIRCUITRY IN SEPARABLE PORTIONS OF THE CASE WITH THE BATTERY CONTACTS ARRANGED SO THAT WHEN THE CASE IS OPENED THE BATTERY IS FIRST DISCONNECTED FROM THE CONTROL CIRCUIT AND THEN A NORMALLY OPEN SWITCH IS CLOSED TO CONNECT A RESISTOR ACROSS THE CAPACITOR TO DISCHARGE IT. THE POWER PACK ALSO INCLUDES AN "ON" INDICATOR LAMP FLASHED BY A RELAXATION OSCILLATOR AND MECHANICAL STRENGTH AND CONVENIENCE FEATURES IN THE CASE.

Phase lock loop for a voltage controlled oscillator

Abstract: A phase locked voltage controlled oscillator having an automatic sweep and lock-up circuit employing a unijunction transistor relaxation oscillator as the controlling device in the circuit.

Wide frequency range voltage controlled transistor relaxation oscillator

Abstract: A VOLTAGE CONTROLLED OSCILLATOR PROVIDING OUTPUT PULSES CONTROLLABLE IN FREQUENCY OVER A WIDE RANGE FROM A FEW HUNDREDTHS OF A HERTZ TO MEGAHERTZ WITH A HIGH DEGREE A ACCURACY AND STABILITY. THE OSCILLATOR EMPLOYS A TRANSISTOR CONSTANT CURRENT SOURCE FOR CHARGING AN ADJUSTABLE R-C TIMING CIRCUIT WHICH TRIGGERS A FEEDBACK CONTROLLED SWITCHING TRANSISTOR CIRCUIT. THE SWITCHING TRANSISTOR CIRCUIT ACTIVATES A SEPARATE TRANSISTOR DISCHARGE CIRCUIT WHICH ALSO SERVES FOR ISOLATING THE TRIGGERING INPUT FROM THE SWITCHING TRANSISTOR DURING SWITCHING TO ALLOW RAPID RESET OF THE TIMING CIRCUIT AND TO IMPROVE THE OUTPUT WAVEFORM.

Temporary memory restore circuit for multivibrator

Abstract: There is provided a temporary memory restore circuit for actuating a bistable multivibrator to its last stable state prior to removal of power, when power is returned to the circuit. The memory restore circuit includes a storage capacitor, which is connected across the output of the bistable multivibrator. The capacitor monitors the operation of the multivibrator and is charged in accordance with the last stable state of the multivibrator. Connected in series with the storage capacitor is a normally open circuit means for connecting the capacitor across the output circuit of the bistable multivibrator when power is applied to the circuit, and for disconnecting the capacitor from the circuit when power is removed.

Control apparatus for motors and the like

Abstract: A SPEED CONTROL CIRCUIT FOR A D.C. SHUNT-FIELD MOTOR OF THE CLASS IN WHICH THE CURRENT TO THE MOTOR ARMATURE IS CONTROLLED BY A PHASE-CONTROLLED SCR CIRCUIT, THE PHASE ANGLE OF OPERATION OF THE SCR CIRCUIT BEING IN TURN DETERMINED BY THE TIMING OF TRIGGER PULSES FROM A UNIJUNCTION RELAXATION OSCILLATOR. THE INPUT D.C. CONTROL VOLTAGE, WHICH MAY BE MANUALLY GENERATED OR PRODUCED BY AN EXTERNAL INSTRUMENT, IS COMPARED IN A CLOSED-LOOP SERVO ARRANGEMENT WITH A FEEDBACK VOLTAGE, DEVELOPED ACROSS A FEEDBACK RESISTOR, WHICH IS INDICATIVE OF THE VOLTAGE ACROSS THE ARMATURE, THE BASE-TO-EMITTRER DYNAMIC CHARACTERISTIC OF A CONTROL TRANSISTOR IS USED IN THE ERROR DETECTION PROCESS TO COMPARE THE FEEDBACK VOLTAGE WITH THE INPUT CONTROL VOLTAGE. THE COLLECTOR CURRENT OF THE CONTROL TRANSISTOR DETERMINES THE CURRENT FED TO THE RELAXATION-OSCILLATOR TIMING CAPACITOR SO AS TO VARY THE FIRING ANGLE OF THE SCR CIRCUIT. THE INTERNAL BASE-EMITTER VOLTAGE OF THE CONTROL TRANSISTOR COMBINED WITH THE VOLTAGE DROP IN THE ABOVE-MENTIONED FEEDBACK RESISTOR PROVIDES A CONVENIENT VOLTAGE-OFFSET LEVEL WHEN AN EXTERNAL INSTRUMENT IS USED TO PRODUCE THE CONTROL VOLTAGE. THE ADVERSE EFFECTS OF PULSATIONS IN THE FEEDBACK VOLTAGE ARE MITIGATED BY A NEUTRAILIZING CIRCUIT WHICH FEEDS THE HIGHERFREQUENCY PULSE COMPONENTS BOTH TO THE EMITTER AND TO THE BASE OF THE CONTROL TRANSISTOR, AN ARRANGEMENT WHICH AT THE SAME TIME RETAINS ADEQUATELY FAST RESPONSE TO TRANSIENTS AND GOOD CIRCUIT STABILITY. AN IMPROVED AND SIMPLIFIED TRANSISTOR CIRCUIT IS UTILIZED FOR LIMITING THE MAXIMIUM CURRENT THROUGH THE ARMATURE, IN WHICH CIRCUIT A VOLTAGE INDICATIVE OF ARMATURE CURRENT IS APPLIED BETWEEN BASE AND EMITTER OF A TRANSISTOR SO THAT, WHEN THE ARMATURE CURRENT EXCEEDS A PREDETERMINED VALUE, THE INHERENT BASE-EMITTER JUNCTION VOLTAGE OF THE TRANSISTOR IS EXCEEDED, CAUSING THE TRANSISTOR TO TURN ON AND TO BYPASS THE NOMINAL CONTROL CIRCUIT FOR THE CONTROL TRANSISTOR. THE EFFECTS OF LINE VOLTAGE VARIATIONS AND OF MOTOR WARMUP ARE COMPENSATED BY DERIVING A VOLTAGE RELATED TO THE FIELD CURRENT OF THE MOTOR AND COMBINING IT WITH THE INPUT CONTROL VOLTAGE OF THE SYSTEM BY WAY OF A ZENER DIODE.

Improvements relating to pulse generators

Abstract: 1,103,825. Capacitor supply systems for discharge lamps. ELECTRIC & MUSICAL INDUSTRIES Ltd. 13 May, 1965 [13 May, 1964], No. 19867/66. Heading H2H. [Also in Division H3] In a pulse generator of the type in which a capacitor or pulse forming network 13 is charged from the rectified output of a transformer coupled relaxation oscillator and subsequently discharged via a switching device (such as 14), the switching device is triggered by a signal induced in a winding of said transformer during the intervals in which the capacitor is not being charged. As described transistor 6 is regeneratively coupled by windings 4, 7 of a transformer so as to form a freerunning of triggered blocking oscillator, the duration of pulses from which is determined by the time taken for the current in winding 4 to reach a value such that transistor 6 is no longer saturated. Each high voltage pulse from the secondary winding 10 resonantly charges an artificial line 13 via a diode 11 which is subsequently discharged via a thyristor 14 and a pulse transformer 15 feeding a magnetron load 2. Thyristor 14 may be triggered by the next pulse from an auxiliary winding 17 after amplification, delay or differentiation at 18. The thyristor 14 may be replaced by a triggered or non-triggered spark gap or a thyratron. H2H: Electricity supply to flash tubes.-The invention may alternatively be applied to a Xenon flash tube which may be connected in place of thyristor 14.

Design of an amplitude-stable sine-wave oscillator

Abstract: Two difficulties associated with the design of oscillators are to achieve amplitude and frequency stability. The latter problem is generally one of selecting the proper components, whereas the former dictates what basic type of oscillator should be designed. When amplitude stability and distortion are not critical considerations, a simple limiting type of oscillator is often adequate. One method of attaining amplitude stability is to incorporate an additional feedback loop, such as Automatic Gain Control (AGC) loop. This type of loop can be easily incorporated with the basic Wein-bridge oscillator. As will be shown by employing integrated circuits, such as the /spl mu/A709, an amplitude stability of /spl plusmn/0.50 percent over a temperature range of -50/spl deg/C to 100/spl deg/C can be achieved.

Capacitance responsive circuit

Abstract: The invention provides a capacitance-responsive circuit for controlling a relay. The circuit includes a relaxation oscillator having a neon tube, a transistor amplifier also having a neon tube, a semiconductor switch and a relay. The relaxation oscillator is operated by a combination of AC and DC power inputs whereby the neon tube of the oscillator conducts relatively early in each negative half-cycle and the magnitude of the initial output pulse of the oscillator, in each pulse train generated in each negative half-cycle, is increased. The oscillator output is fed as input to the transistor amplifier and the neon tube thereof regulates the bias voltage of the transistor, protects the transistor from excessive junction voltage and stabilizes the tube of the oscillator by illuminating it. The semiconductor switch controls a shunt path for the winding of the relay, and the shunt path includes a diode and a first resistor connected in parallel with each other and in series with a second resistor, whereby heat generated is less than with the second resistor alone.

Touch-responsive oscillator-controlled circuit

Abstract: Electric control device actuated by manual bridging of spaced contacts acting on the capacitance of a relaxation oscillator to block oscillation, and a signal circuit providing a signal voltage only in response to oscillations, Circuit includes a time delay so that variations or interruptions in the manual application of the resistive impedance across the contacts, as by nervous persons will not affect the signal.

Voltage to frequency converter

Abstract: A VOLTAGE CONTROLLED, VARIABLE FREQUENCY RELAXATION OSCILLATOR INCLUDES A PAIR OF METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTORS (MOSFET''S) FEEDING VARIABLE CURRENTS TO TRANSISTORS COMPRISING THE OSCILLATOR. THE GATE ELECTRODES OF THE MOSFET''S ARE CONNECTED IN PARALLEL WITH A FREQUENCY CONTROLLING SIGNAL SOURCE TO PROVIDE A HIGH IMPEDANCE TO THE SOURCE. TO COMPENSATE FOR THE TENDENCY OF THE MOSFET''S TO PRODUCE A NONLINEAR OSCILLATOR OUTPUT FRE- QUENCY AS A FUNCTION OF SOURCE SIGNAL LEVEL, SPECIAL CIRCUITRY IS PROVIDED. TO MAINTAIN THE OSCILLATOR RESPONSE CONSTANT AS A FUNCTION OF TEMPERATURE AND COMPENSATE FOR VARIATIONS IN THE CHARACTERISTICS OF THE MOSFET''S AS A FUNCTION OF TEMPERATURE, A REGULATOR CIRCUIT INCLUDING A MOSFET AS A VOLTAGE REFERENCE SOURCE IS PROVIDED.

Capacitor type timing circuit utilizing energized voltage comparator

Abstract: There is provided a strobed timing circuit which includes a timing capacitor connected across a voltage source for charging at a predetermined rate, and a comparator circuit for providing an output signal when the voltage across the capacitor reaches a set-in value. The comparator circuit is turned on for relatively short intervals of time to measure the voltage across the capacitor to thereby provide a comparator circuit with an apparently high input impedance.

Pseudo voltage controlled oscillator

Abstract: For use in a VLG navigation system, such as the Omega Navigation system, a phase tracking loop in a receiver receives incoming signals from transmitting stations. The tracking loop contains four electronically controlled pseudo voltage-controlled oscillators, to eliminate the need for all but one master crystal oscillator, whose outputs provide necessary signals within the receiver. The pseudo oscillator comprises an integrator and a voltage-to-phase converter using an external clock pulse input and suitable control logic. The voltage-to-phase converter comprises a one-shot multivibrator in which the delay time is proportional to the input signal level. Thus, the periods between return times of the one-shot multivibrator to its original state provide a frequency which is controlled by input voltage level. When the phase-shift range exceeds + OR - 90* , the trigger pulse to the one-shot multivibrator is advanced or delayed, and the integrator is reset to zero.

High power modulator

Abstract: A device providing medium voltage, high current switching into a load with nonlinear characteristics. The square wave output of a clocked flip-flop is amplified and used to operate a switching transistor which controls the power to the load.

Semiconductor switching circuit

Abstract: 1,128,695. Touch switches. WAGNER ELECTRIC CORP. May 16, 1967 [May 17, 1966], No. 22647/67. Heading G1N. [Also in Division H3] A switching circuit, responsive to touch, comprises a switch 28 composed of a pair of complementary transistors 30, 31 with the base of each connected to the collector of the other, an A.C. power supply 20, 23 coupled to the emitters of the transistors, an input circuit connected between the base and emitter of one transistor (31) to supply a switching signal through a capacitor 27, and a bias circuit including a capacitor 35 and a resistor 34 connected in series between the base and emitter of the one transistor. A reverse bias for switch 28 is stored on bias circuit 34, 35, the charge being maintained through the zener breakdown of transistor 30 on the half cycles of the A.C. supply when line 18 is positive. A relaxation oscillator, comprising a neon lamp 10, capacitor 16 and resistors 21, 14, 15, 17 oscillates at a frequency (e.g. 2-4 Kc/s) much greater than that of the A.C. supply, the oscillations being normally of sufficient magnitude, after amplifier stage 24, to render switch 28 conductive when line 18 is negative. However, should antenna 12 be touched, e.g. by the human hand, the magnitude of the oscillations is so reduced that switch 28 is not rendered conductive, and current is diverted through relay 38 to close contact 41. Current flow through relay 38 during positive half cycles at line 18 is prevented by diode 37, but when antenna 12 is touched, and thus switch 28 is maintained non- conductive, relay 38 is maintained energized during positive half cycles by the charge stored on capacitor 40.

Improvements in electrically operated drive systems

Abstract: 1,263,261. S.C.R. circuits. SEVCON ENG. Ltd., and RANSOMES SIMS & JEFFERIES Ltd. 5 Feb., 1969 [6 Feb., 1968], No. 5924/68. Heading H3T. [Also in Division H2] A traction system comprises series motors 1, 2 supplied from battery 3 through thyristors 4, 5 whose gates are connected through pulse delay circuits 8, 9 to a master oscillator 10. A speed controller 11 comprising an accelerator pedal varies the output pulses from the oscillators, whilst a pulse width regulator 12 actuates a commutating circuit 13 to switch off the main thyristors. A potentiometer 14 which is operated by a steering wheel changes the delay of either circuit 8 or 9 whilst the delay of the other circuit remains constant. Depression of the pedal increases the frequency of pulses supplied to the main thyristors whilst rotation of the steering wheel increases the delay of pulses supplied to one of the thyristors. The circuit 13 commutates the thyristors simultaneously so that a delay caused by circuit 8 or 9 reduces the mean current fed to the motor which drives the inside wheel when the vehicle moves in a curved path. The frequency control effected by the oscillator 10 may be replaced by variable pulse width control. Closure of key switch 23 charges capacitor 18 which is reverse charged when a pulse from the master oscillator triggers thyristor 22. Thyristors 4, 5, are commutated by firing thyristor 17 from circuit 12. The capacitor 18 is discharged through the battery and then forward charged in excess of the battery voltage through the motors, diodes 15, 19, inductor 16 and thyristor 17. The latter then becomes non-conductive and the cycle is repeated by firing the thyristor 22 and the main thyristors. Referring to the master oscillator, the potentiometer 11 controls the rate of charge of a capacitor forming part of a relaxation oscillator associated with a transformer for triggering the thyristor 22, as well as being connected to the circuits 8 and 9. This capacitor is not charged until the capacitor 18 is fully forward charged, Fig. 3 (not shown). Referring to the pulse width regulator, when thyristor 22 is fired to reverse the charge on capacitor 18, a pair of transistors are made non- conductive to allow charging of a timing capacitor until a further transistor conducts to discharge the capacitor. A pulse is then applied through a transformer to trigger the thyristor 17, Fig. 4 (not shown). Each delay circuit comprises a multi-vibrator which is triggered by the master oscillator and which is controlled by the charging of a capacitor associated with a timing resistor. The main thyristor is fired a predetermined period after the arrival of the initiation pulse. The timing resistor has its effective impedance varied by a shunt transistor associated with a non-linear network and controlled by the steering potentiometer. The pulse delay effected by the circuit 8 or 9 is thus a non-linear function of the steering angle, Fig. 5 (not shown). In modifications, the motors may drive the wheels of fork lift truck and an hydraulic pump for auxiliary services of the vehicle respectively, or the motors may be coupled to tracks on opposite sides of a vehicle. Field control instead of armature control may be provided. To avoid overloading the main thyristors 4, 5, the current therethrough is limited. Pick-up coils are disposed adjacent the thyristors and connected in phase opposition to the input of a full wave rectifier the output of which is connected in series with a further coil responsive to the battery current. These coils are associated with a current limit detector for reducing the frequency of the master oscillator when the output of the detector exceeds a predetermined value, Fig. 6 (not shown). Further commutating arrangements for the thyristors 4, 5, are described in Specification 1,263,262.

Direct current or alternate current converter having variable pulse width and frequency

Abstract: A DC TO AC INVERTER INCLUDES A FIRST PAIR OF COMPLEMENTARY TRANSISTORS HAVING THEIR RESPECTIVE COLLECTOREMITTER CIRCUITS COUPLED IN SERIES WITH AN INDUCTIVE LOAD. THE SECOND PAIR OF COMPLEMENTARY TRANSISTORS SIMILARLY HAVE THEIR COLLECTOR-EMITTER CIRCUITS COUPLED IN SERIES WITH THE LOAD. OF THE RESPECTIVE PAIR, BOTH FIRST TYPE TRANSISTORS HAVE THEIR COLLECTOR-EMITTER CIRCUITS COUPLED TO A DC SOURCE TERMINAL AND BOTH SECOND TYPE TRANSISTORS HAVE THEIR COLLECTOR-EMITTER CIRCUITS COUPLED TO THE OTHER DC SOURCE TERMINAL. THE BASES OF THE FIRST TYPE TRANSISTORS ARE NOW SIMULTANEOUSLY DRIVEN BY AN INDEPENDENT OSCILLATOR CIRCUIT TO EFFECT THE CONVERSION. TWO TYPES OF OSCILLATOR CIRCUITS ARE SHOWN. THE FIRST INCLUDES AN RC COUPLED OSCILLATOR OF VARIABLE FREQUENCY, AND THE SECOND A RELAXATION OSCILLATOR IN TANDEM WITH A TYPICAL OSCILLATOR CIRCUIT TO FORM A VARIABLE PULSE WIDTH OSCILLATOR.

Cycling delay circuit testing device

Abstract: A voltage cycling testing device for a delay circuit A unijunction relaxation oscillator delivers a trigger pulse to a monostable multivibrator which activates a relay to apply power to a circuit under test The unijunction transistor is activated periodically for a predetermined time period by a resistancecapacitance network The relay is deactivated each time the multivibrator switches back to its stable state

Electric windscreen wiper systems

Abstract: In an electric windscreen wiper system, pulsed operation of the wipers is obtainable by means of a circuit, in which the electric wiper motor is intermittently connectable to an electric power source by a relaxation oscillator circuit which includes a unijunction transistor.

A Synchronous Sweep Frequency Oscillator

Abstract: This paper describes a linear frequency sweep oscillator which is accurately controlled by a master clock. The voltage controlled oscillator which generates the frequency sweep is first phase-locked to the master clock. Then, a ramp generator drives the voltage controlled oscillator over the required frequency range, while a phase-sampling loop controls the instantaneous frequency to the desired ramp accuracy. The phase-sampling control loop is synchronized to the master oscillator by the sampling rate, which is derived directly from the master clock frequency. A laboratory system constructed on these principles sweeps from 2.095 MHz to 2.320 MHz in approximately 1.709 seconds, with a deviation from linearity of less than ±75 Hz.

A new wide range free-running multivibrator†

Abstract: A now multivibrator circuit which provides a large frequency range with a single control is described. Capacitive feedback is applied to a basic differential amplifier resulting hi relaxation oscillation. The circuit provides waveforms that have short rise and fall times over the entire range. With the experimental circuit, a frequency range extending from fractions of a cycle to over 1 megacycle was achieved.

Quartz-controlled transistor oscillator

Abstract: A QUARTZ CONTROLLED TRANSISTOR OSCILLATOR USABLE FOR TRANSMITTING AND RECEIVING CONVERTERS OF DIRECTIONAL RADIO SYSTEMS OPERATING IN THE GIGAHERTZ RANGE WHEREIN A BRIDGE CIRCUIT CONTAINING THE QUARTZ CRYSTAL IS IN CIRCUIT BETWEEN TWO TRANSISTORS, AND A FEEDBACK PATH BETWEEN THE TRANSISTORS INCLUDES A NETWORK SHIFTING THE PHASE IN DEPENDENCE ON THE OSCILLATING FREQUENCY OF THE QUARTZ.

Improvements in or relating to voltage stabilising means for dc to dc converters

Abstract: 1,102,494. Converting circuits. E. K. COLE Ltd. 21 March, 1966 [20 March, 1965], No. 11939/65. Heading H2F. [Also in Division H3] A relaxation oscillator used in an A.C. to D.C. converter has its output amplitude stabilized against variations in output impedance by means of a Zener diode 18 connected across the collector-emitter path of the oscillator transistor 4 so as to conduct when the transistor is cut off. The circuit provides an increase in output with a decrease in supply voltage 7 and in order to compensate for this part of the supply voltage may be injected in opposition into the output circuit by replacing link 19 with a potentiometer circuit 20. A plurality of outputs may be provided, each taken from a separate secondary winding 3, and each having its own potentiometer circuit.