Abstract: A voltage controlled bridge is coupled to a line voltage and a transformer primary harmonic voltage, and a current controlled bridge is coupled to a line current and a transformer secondary harmonic voltage. A synchronous average harmonic current compensator integrates error between a measure of bridge current and commanded current synchronously over each half of a switching period and samples compensator output to control line current and linearize harmonic coupling between isolated bridges. A synchronous pulse width modulation process tracks commanded line voltage. One or more of a primary harmonic command circuit and secondary harmonic command circuit adjust the harmonic coupling voltage of the voltage controlled and current controlled bridge respectively. Line voltage, line current, and primary and secondary harmonic commands provide generalized line and isolated voltage bus regulation degrees of freedom in a single stage.

Abstract: A synchronous average harmonic current controller is used to simultaneously control line load current and switching transformer current for a resonant power converter. The controller takes its feedback input from a current command and a bridge current sensor which measures total current flowing between the bridge switching nodes. The controller is implemented using an inverting switched capacitor filter. The filter switches two capacitors across the output and inverting node of an error amplifier to integrate and compensate current error synchronously over each half of the fundamental period. The superimposed non-modulated common and modulated difference feedback signals apply duty cycle and phase control which reduces the synchronous average error current. As a result of synchronous average current control of the line load and transformer currents, the primary and secondary bridge have a defined voltage relationship which is straightforward to regulate.

Abstract: A cantilever fan including a blade and a blade permanent magnet. The blade is clamped at one end to a base and has a distal end which is free to oscillate with distal end having the largest swept displacement of any portion of the blade. The blade extends from the clamped end to the distal end. The blade permanent magnet is attached only to the blade at a point along the blade's length and is free to move with the blade. The fan includes a stationary permanent magnet attached only to the base. The respective locations and relative orientation of the blade permanent magnet and stationary magnet result in a repulsive magnetic force between the blade permanent magnet and stationary magnet. The fan is configured so that the repulsive force increases as the blade's deflection brings the blade permanent magnet closer to the stationary magnet.

Abstract: A horological movement (6) including: a plate (7); a mechanical resonator (8) including an oscillating balance (11) rotatably mounted relative to the plate (7), and a spiral spring (22) coupled to the balance (11); an electromagnetic regulator (29) coupled to the mechanical resonator (8) to regulate the frequency of the oscillations of the balance (11), and including at least one permanent magnet (30) fixedly mounted relative to the plate (7), at least one coil (31), a quartz or silicon resonator (32) and an electronic circuit (33) connected to the resonator (32) and to the coil (31), all mounted on the balance (11) while being completely included in an inner cavity (18) delimited by the latter.

Abstract: A timepiece includes a mechanical movement with a mechanical oscillator and an electronic device for regulating the medium frequency of this mechanical oscillator. It includes an electromagnetic transducer and an electric converter which includes a primary storage unit for powering the regulation circuit. The electromagnetic transducer is arranged to supply a voltage signal exhibiting first voltage lobes in first half-alternations and second voltage lobes in second half-alternations of the oscillations of the mechanical oscillator. The regulating device includes a load pump arranged to transfer electric loads from the primary storage unit into a secondary storage unit, these electric loads being extracted selectively in different time zones according to a time drift detected in the functioning of the mechanical oscillator relative to an auxiliary oscillator, particularly quartz-based.

Abstract: An apparatus for determining and/or monitoring at least one process variable of a medium in a container, comprising: a mechanically oscillatable unit; an electrodynamic transducer unit for exciting the oscillatable unit by means of an exciter signal to execute mechanical oscillations and for receiving the mechanical oscillations of the oscillatable unit and transducing them into an electrical, received signal; and an electronics unit, which at least determines and/or monitors the process variable based on the received signal. The invention is distinguished by features including that the electrodynamic transducer unit has exactly one coil, which serves both as a drive element as well as also a receiving element.

Abstract: A motor drive controller includes: a motor driver that applies a voltage to each phase of a motor to rotate; a rotational position detector that detects rotational position of the motor and generates rotational position information indicating the rotational position; and a controller that outputs, to the motor driver, driving control signals for repeatedly adjusting an advance angle and a lag angle at energization switching of the each phase of the motor in a prescribed pattern based on the rotational position information generated by the rotational position detector.

Abstract: A mechanism drives the hands of an electromechanical watch. It includes an electric motor, a set of gear wheels connected to the electric motor to move the hands forward or backward on each actuation of the electric motor, and a locking device. The locking device includes a piezoelectric actuator for locking, in a rest mode, directly or via a bolt, one wheel of the set between each actuation of the electric motor. The piezoelectric actuator releases the wheel of the set of gear wheels, when it is actuated by an electrical signal at the moment of each actuation of the electric motor to move the hands forward or backward.

Abstract: An applicant dispersal assembly is described that couples to an irrigation system. It is contemplated that the irrigation system may be a center pivot irrigation system, a linear move irrigation system, or the like. The applicant dispersal assembly is configured to receive an applicant and selectively adjust a flow rate of the applicant. In an implementation, the applicant dispersal assembly includes a pump assembly configured to couple to an irrigation conduit. The irrigation conduit is configured to provide an applicant to the pump assembly for dispersing over a cultivation area. The pump assembly is configured to pump the applicant and to selectively adjust a flow rate of the applicant. The applicant dispersal assembly also includes an applicant dispersal device that is coupled to the pump assembly. The applicant dispersal device is configured to disperse the applicant.

Abstract: In one embodiment, a cryocooler drive circuit for a cryocooler motor is provided that includes: a first switching power converter configured to track a first sinusoidal input voltage signal to provide a first sinusoidal output voltage signal at a first output node; and a second switching power converter configured to track a second sinusoidal input voltage signal to provide a second sinusoidal output voltage signal at a second output node, wherein the second sinusoidal input voltage signal is an inverted version of the first sinusoidal input voltage signal such that the cryocooler motor is driven by an alternating current flowing between the first and second output nodes.

Abstract: A power converter includes a first electric power conversion unit having an inverter for converting a first DC electric power to an AC electric power, an AC circuit connected to the first electric power conversion means; a second electric power conversion unit for receiving the first DC electric power and converting the same to a second DC electric power having a voltage level that differs from the voltage level of the first DC electric power, a power storage unit for storing the second DC electric power of the second electric power conversion unit; and a ripple suppressor having a first inductance for guiding the second DC electric power of the second electric power conversion unit to the power storage means and a second inductance for suppressing the ripple component included in the second DC electric power arranged between the second electric power conversion unit and the power storage unit.

Abstract: The present invention provides a DC-AC frequency converter type mucus suction device having an electromagnetic pump, the pressure and the flow generated in which could be changed to satisfy the requirement of the mucus suction device. The mucus suction device of the present invention comprises an electromagnetic pump, a suction device and a frequency converter circuit, wherein the frequency converter circuit at least comprises an oscillator circuit, a bistable circuit, and a push-pull circuit, wherein the electromagnetic pump is supplied with AC obtained from the oscillation of DC in the frequency converter circuit, wherein the swing speed, frequency and amplitude of the swing arms vary with the oscillation frequency of the oscillator circuit, such that the suction pressure and the suction flow of the electromagnetic pump could further be changed to obtain the most appropriate pressure and flow of the mucus suction device.

Abstract: An electromagnetic pump has a frequency converter circuit for driving the electromagnetic pump, wherein the frequency converter circuit comprises an oscillator circuit, a bistable circuit and a push-pull circuit. The oscillator circuit oscillates to transform DC into a single-phase oscillating signal. The bistable circuit splits the single-phase oscillating signal into a N-phase stimulus signal and a S-phase stimulus signal. The push-pull circuit amplifies and transports the N-phase stimulus signal and the S-phase stimulus signal to the electromagnetic pump to make the swing arms of the electromagnetic pump swinging effectively, wherein the swing speed, the swing frequency and the swing amplitude of the swing arms vary with the change of the oscillation frequency of the oscillator circuit.

Abstract: A dual mode vibrator is disclosed. There are available two vibrating units to enable obtainment of a variety of vibrations. Each lateral portion of the first and second vibrating units respectively supported by the first and second elastic members is supported by the first and second support bars secured at the housing for rotatable installation. Therefore, although the first and second vibrating units may rotate about the first and second support bars, the first and second vibrating units are not allowed to deviated or disengaged from the first and second support bars, whereby the plastic deformation of the first and second elastic members is prevented, and the first and second vibrating units can be positioned at predetermined positions at all times to enhance reliability of product.

Abstract: An electric vehicle comprising a drive wheel which is driven by a traction electric motor, a brake command device, a brake releasing unit, a brake shaft, a friction plate, and a braking spring. The brake shaft is rotatable in a brake realizing direction which is one direction by an operation of the brake command device, and is rotatable in a brake releasing direction which is the other direction by driving of the brake releasing unit. The friction plate is operatively connected to the traction electric motor, and is frictionally braked when the brake shaft is rotated in the brake realizing direction. The braking spring applies an elastic force to the brake shaft in a direction to rotate the brake shaft in the brake realizing direction.

Abstract: A method for closed-loop control of a linear drive including a stator, a rotor configured for reciprocating movement along a drive axis therein, and a drive coil through which coil current flows, in particular for a linear compressor including a piston housing and a compressor piston configured for reciprocating movement along a piston axis therein, and driven by the linear drive wherein the coil current is subject to closed-loop control, the method including the steps of determining a target coil current and applying an actual coil current wherein the actual coil current and the target coil current are substantially the same value.

Abstract: A method of protecting a cylinder of a compressor comprising a piston, a linear permanent magnet (PM) having a coil and a magnet, and a sensor-less control of the PM for moving the piston in and out of the cylinder. The method including the steps of receiving a reference position of the piston from a temperature control loop; deriving a compensation voltage and a load spring effect information from a current through the coil; providing a model input voltage to a model of a mechanical structure of the compressor for predicting position of the piston, the model input voltage comprising a first voltage derived from the reference position; a compressor input voltage comprising the first voltage and the compensation voltage; and using a position control loop to recognize when the maximum compression ratio is desired and controlling the piston to achieve maximum compression ratio without causing damage to the discharge valve.

Abstract: A brushless motor circuit is for driving a brushless direct current (BLDC) motor. The motor includes a rotor and exciting coils for respective phases in a three-phase winding in a star configuration. A neutral point in the star configuration is configured to switch to one of a ground voltage, a supply voltage, and an open circuit voltage to provide more combinations. The combinations provide extra steps in one revolution for a better resolution with enhanced efficiency.

Abstract: An exemplary embodiment of the invention is a power system for providing power to a critical load. The system includes a first power source producing sufficient power to supply the critical load and a second power source, independent of said first power source. The second power source produces sufficient power to supply the critical load. The system also includes a rotary device having a first power input circuit and a second power input circuit. The second power source is coupled to the rotary device at the second power input circuit. A transfer switch selectively couples the first power source to the first power input circuit and the second power input circuit.

Abstract: A system is disclosed which comprises an electrical actuator (2), a current source (35), a actuating unit (37) having a limited operating range, and a control unit (41). The actuator comprises a first actuator body having two diametrially opposed magnetic poles, and a soft-magnetic second actuator body, which is coaxial with the first actuator body and which preferably comprises three circumferentially equi-spaced teeth, which each carry an energizing coil (29, 30, 31). The first actuator body and the second actuator body cooperate with one another via an air gap and are pivotable relative to each other through a specific angle about a pivotable axis. The control unit is constructed to divide the operating range of the actuating unit into a plurality of sub-ranges and, depending on said sub-ranges, to controllably feed a current through one of the energizing coils, through two of the energizing coils, and through all the energizing coils, respectively.

Abstract: A direct current powered, linear resonant cryocooler having a compressor in which the piston is reciprocated by a linear motor at substantially resonant frequency and the length of stroke of the piston is varied as a direct function of cryocooler temperature. There are two control loops, a temperature control loop and a voltage control loop which is independent of the temperature control loop. In the temperature control loop, temperature is sensed at the cryocooler or expander and the temperature signal is compared with a reference temperature signal to produce a temperature error signal or voltage. The voltage control loop controls motor voltage. As input to the voltage control loop, the linear motor voltage is fed back and compared with the temperature error voltage V.sub.TE to produce a voltage level signal V.sub.L in the input of the voltage control loop, representative of the correction required to obtain and then to maintain the cryocooler temperature represented by the reference temperature voltage.

Abstract: An electromechanical linear motor incorporating a number of electrically conductive drive coils arranged axially and embedded in a composite matrix so as to form a hollow cylinder within which a piston or pistons are placed. Permanent magnets or conductive coils arranged around the circumference of the pistons interact through magnetic coupling with the drive coils so as to cause the piston to move in accordance with the currents applied to the drive coils. These currents are supplied through logic control circuitry which receives inputs from a number of sensors including piston position sensors, thermostats, pressure transducers and timers. Based on the information received from these sensors, a microprocessor controlled power circuit provides electrical pulses of a frequency, amplitude and duration designed to produce piston motion appropriate to the specific application.

Abstract: An arrangement to controllably vibrate a resiliently supported body including electromagnetic drive means energizable to vibrate the body, means to control the device means, means to detect the actual vibration of the body, the control means including digital signal processing means to produce a control pulse train representing a required phased difference from the detected vibration to control the energization of the drive means with an independently set phase difference from the detected frequency to sustain the vibration of the body.

Abstract: An apparatus comprising a rocker with a curved base, and an activating base supporting and continuously activating the rocker. Two magnets, whose north poles point in opposite directions, one upward and the other downward, are respectively disposed on either side, towards which rocker rocks, of the center of gravity of the curved base. A first induction coil is set within the activating base and under the rocker so as to produce induced a current when the rocker is rocking in the direction of one of the two magnets. An operational amplifier integrated circuit (OP AMP IC) is provided within the activating base so as to amplify the induced current. A second induction coil, which is connected to the output of the OP AMP IC, is provided so as to induce a magnetic field. This magnetic field applies an attractive force on the magnet when it moves closer to the activating base, and a repelling force on the other magnet moving away from the activating base so as to activate the rocking means.

Abstract: An electromagnetic reciprocating motor or pump for use for providing mechanical force for actuation of other fluids or components, and includes a cylinder provided with closures at each end, at least a pair of electromagnets operatively associated with the cylinder, and surrounding the same, a magnetically responsive piston provided within the cylinder and capable of longitudinal shifting reciprocally within the cylinder upon the sequential energization of the electromagnets, and either a mechanical actuator or electronic triggering components cooperating with electrical circuitry and connecting with the electromagnets which upon energization charging the electromagnets in timed sequence for inducing their reciprocal shifting of the piston within the cylinder means.

Abstract: A method of and apparatus for measuring the vibration amplitude of an electromagnetic vibratory motor is disclosed in which the current induced in the coils of the motor is sensed and differentiated and applied to dividing means where it is divided by the sensed induced voltage induced in the coils to produce a signal proportional to the instantaneous reluctance of the coils of the vibratory motor. The instantaneous reluctance signal is filtered to remove the line frequency harmonic therein, and this filtered signal is peak detected to produce the vibration amplitude signal. Means are also provided to eliminate the problem associated with the dividing means if the sensed induced voltage approaches zero.

Abstract: A linear electric motor having an oscillating linear armature disposed in proximity to a stationary stator and provided with an output member which can be directly coupled to a load. A power supply and control circuit is provided for matching the power input to the linear motor according to changing load conditions at the output.

Abstract: A reciprocating electric motor employs plural motor stator modules each including a group of coils selectively energized in subgroups to produce a magnetic field sweeping from one end of the group to the other and then repetitively from the same one end to the other always in the same direction until a number of ferromagnetic non-ferromagnetic armature sections each equal in length to the length of the stator modules and equal in number to the stroke of the motor divided by the length of each section has passed the stator module and thereafter the sequence of energization is reversed to move the armature a like distance in the opposite direction, the several coils of each group being electrically connected in a set each of which has its own power supply, the power supplies being collectively controlled by a microprocessor.

Abstract: A variable-frequency feeder control using a single oscillator to develop signals for moving materials in either one of two directions. An output signal from the oscillator is applied to a first timing circuit which develops signal pulses for driving a horizontal electromagnetic drive coil. The first timing circuit controls the duration of the signal pulses which determine the amplitude of power to drive the horizontal coil. The output signal from the oscillator is applied to a second timing circuit which developes a phase shifted signal to control the phase between the power applied to the horizontal coil and the power applied to a vertical drive coil. A third timing circuit uses the phase shifted signal to develop signal pulses for driving the vertical coil and controls the duration of the drive pulses.

Abstract: An electromagnet hammer of the type described in U.S. Pat. No. 4,215,297 is autosynchronized by triggering the discharge thyristor in response to the detection of the position of the armature by a proximity detector, or by direct detection of the zero passage of the negative amplitude of the discharge current, or at a reference point representing the position of the armature, with a delay equal to at least half the period of the natural period of oscillation of the armature/plunger and its elastic suspension.

Abstract: A subharmonic controller for a dual coil electromagnetic vibrator, which derives both power and timing from a conventional a.c. line, having a zero crossing detector providing pulses at twice line frequency to a phase control. The phase control provides a selectively variable pulse width and triggers a frequency divider, which in turn triggers a divide-by-two-counter. Pulses from each of the phase control, divider and counter are fed to a logic controller which generates plus and minus gate signals. The gate signals alternately fire a pair of oppositely-directed SCR's, each SCR connected in series with one of the dual coils across the a.c. line. A polarity detector and reset circuit restore the polarity information and synchronize it with the direction of conduction of the SCR's.

Abstract: A vibrator control circuit is provided for controlling the driving current supplied to the driving coil of an electromagnetic vibrator for a bed or the like. The control circuit is adapted to be connected to source of A.C. line voltage such as a standard wall outlet and controls the duration of the portion of each cycle of the A.C. line voltage supplied to the vibrator. The control circuit includes an electronic switch, e.g., a transistor, connected in series with the driving coil of the vibrator and a control pulse generator for supplying control pulses to the electronic switch to control switching of the electronic switch in timed relationship with respect to the A.C. line voltage waveform so as to gradually vary the duration of the portion of the A.C. line voltage supplied to the electromagnetic vibrator during each cycle of the A.C. line voltage.

Abstract: An electromagnetic reciprocating motor or pump for use for providing mechanical force for actuation of other fluids or components, and includes a cylinder provided with closures at each end, at least a pair of electromagnets operatively associated with the cylinder, and surrounding the same, a magnetically responsive piston provided within the cylinder and capable of longitudinal shifting reciprocally within the cylinder upon the sequential energization of the electromagnets, and either a mechanical actuator or electronic triggering components cooperating with electrical circuitry and connecting with the electromagnets which upon energization charging the electromagnets in timed sequence for inducing their reciprocal shifting of the piston within the cylinder means.

Abstract: A synchronous motor is adjustably positioned on a support plate by screws passing through slots in the support plate. An optical filter is attached to an arm which is secured to the rotor of the motor for horizontal rotation of the arm between two stable positions defined by stops so that the filter is held stable either in or out of the path of a light beam in a spectrophotometer, for example. The stops are spaced and positioned in relation to the stator poles of the motor such that application to two stator coils of the motor of one or the other of two predetermined discrete voltage codes will unambiguously drive the rotor in the direction of a predetermined one or the other of the stops toward a stable pole position of the motor corresponding to that code until movement is terminated by that stop.

Abstract: A synchronized subharmonic controller for a dual coil electromagnetic vibrator, which derives both power and timing from a single phase AC line, having a trigger circuit which operates the coils at one-third the power line frequency. A timing circuit is optically coupled to alternately fire a pair of oppositely-directed SCR's with each SCR connecting one of the coils across the AC line. The optical coupling reduces feedback from the coil circuitry to the timing circuit. A pair of capacitors supply additional power to operate the coils and to reduce the peak values of current supplied by the power line.

Abstract: To obtain high accuracy of the control current in spite of tolerances of operation of the positioned element, a current mirror circuit (18) is provided having two current paths (17, 23). A low resistance resistor (11) is connected in series with the positioned element and the first current path (17) of the current mirror circuit. A command element (22) is connected in the second current path (23) of the current mirror circuit and connected to a command value--actual value comparator (24, 26). Thus, high accuracy of operation and control current is obtained in spite of wide tolerances of the positioning element. Losses in the system are minimized by using pulse width--modulated control thereof.

Abstract: A vibratory amplitude controller for vibratory mechanisms such as a vibratory feeder having in addition to a parts container, an electromagnetic drive unit operated from an A.C. current source for imparting oscillatory motion to the parts container. The controller includes a sensing means for sampling the electromagnetic drive unit current during a specific predetermined interval each A.C. current cycle to produce a vibratory amplitude representing signal. Means responsive to the vibratory amplitude representing signal controls the amount of power delivered from the A.C. current source to the electromagnetic dive unit to maintain a desired vibratory amplitude under varying load and A.C. line voltage conditions.

Abstract: A blocking oscillator for a reciprocating electromagnetic actuator having a solenoid coil, a detection coil for generating a control signal in response to a charge in the magnetic field generated by the solenoid coil, a silicon Darlington amplifier responsive to the control signal to control the current through said solenoid coil, and a diode connected in series with the collector of the Darlington amplifier rendering the Darlington amplifier immune to reverse voltage and transient signals.

Abstract: The invention deals with a method and a circuit for operating a spray gun having a vibrating armature drive which is energized with an electrical a.c. signal. To reduce the liquid which is sprayed per unit of time by the spray gun, a pulse width modulated energizing signal with abruptly rising leading edges is fed to the vibrating armature drive. The circuit includes a control circuit which produces a control signal with abruptly rising leading edges and a controllable switch which electrically couples a supply voltage source and the vibrating armature drive, the control terminal of the switch being connected to the output of the control circuit. The circuit may alternatively have a signal generator which produces a control signal with abruptly rising leading edges and a power amplifier connected to the output of the signal generator, the output of the power amplifier being connected to the vibrating armature drive.

Abstract: A one shot firing circuit for electrically powered tools is described which includes a manually operable normally open trigger switch connected electrically in series with a solenoid coil and an AC power source for controlling the supply of electrical power to both the firing circuit and the solenoid, such that when the trigger switch is open, the path of current flow to the solenoid coil is physically interrupted. The firing circuit also includes an SCR connected electrically in series with the trigger switch, the solenoid coil and the AC power source, for controlling the flow of current through the solenoid coil after the trigger switch has been closed.

Abstract: Circuitry is disclosed for driving the transducer assembly of a dental handpiece at its resonant frequency. The circuitry includes a variable frequency oscillator and a peak-detecting processor which allows the oscillator to sweep through a continuum of frequencies until maximum current in the transducer driving coil is sensed.

Abstract: A material dispensing apparatus including drive structure for driving a feeder bowl is disclosed. A control circuit for controlling the drive includes a Hall effect amplitude sensing transducer for monitoring the magnitude of bowl vibrations and a braking circuit for controlling the damping of vibratory motion after the requisite amount of material has been fed from the feeder bowl. The braking circuit selectively reverses the current flow through a drive coil which comprises a portion of the drive circuitry of the apparatus. This current reversal disrupts the rhythm of forced oscillations which feed material from the bowl and causes bowl motion to be damped. A mechanical brake coupled to the bowl complements the braking action of braking circuit and locks the bowl in place to prevent accidental dispensing of parts.

Abstract: A material dispensing apparatus including drive structure for driving a feeder bowl is disclosed. A control circuit for controlling the drive includes a Hall effect amplitude sensing transducer for monitoring the magnitude of bowl vibrations and a braking circuit for controlling the damping of vibratory motion after the requisite amount of material has been fed from the feeder bowl. The braking circuit selectively reverses the current flow through a drive coil which comprises a portion of the drive circuitry of the apparatus. This current reversal disrupts the rhythm of forced oscillations which feed material from the bowl and causes bowl motion to be damped.

Abstract: A control unit for controlling a vibratory bowl feeder which is effective to maintain, for varying feeder loads, a constant preselected amplitude of bowl feeder vibration at a vibratory frequency which coincides with the changing mechanical resonant frequency of the feeder system. The control unit includes a sensor which detects the amplitude and frequency of feeder bowl vibration, a frequency control loop and an amplitude control loop. The frequency control loop is responsive to the detected frequency of vibration and provides an oscillating signal which coincides with the resonant frequency of the system. The amplitude control loop is responsive to the detected amplitude of vibration and includes a variable gain amplifier which amplifies the oscillating signal to provide a feeder driving signal which causes the feeder to vibrate at the system resonant frequency at a preselected amplitude.

Abstract: A vibrating compressor wherein an alternating voltage is applied from a d-c power source to a drive coil vibrating in a magnetic field via a d-c/a-c converter circuit is disclosed. An alternating voltage of a square wave form is applied to the drive coil of the vibrating compressor in such a manner as to avoid the timing at which a counter electromotive force generated in the drive coil intersects with zero level.

Abstract: An oscillating motor capable of 180.degree. displacement and return without return springs.

Abstract: A vibrator motor is coupled to the frame of a body support structure to vibrate the latter. The motor is energized by a train of triangular pulses modulated by a triangular pulse signal having a lower frequency than that of the triangular pulse train.

Abstract: An electromagnetic hammer has a coil coacting with an axially reciprocable armature including a ferromagnetic core traversed by an elongate nonmagnetic ram which carries at one end a spring-loaded piston head forming part of a pneumatic damping device, its other end co-operating with a working tool. The coil is intermittently energizable by a control system including a capacitor chargeable from an electric power supply by way of a first thyristor and dischargeable through the coil by way of a second thyristor, the two thyristors being sequentially triggered in response to a control pulse applied to a transformer with two secondaries generating staggered firing pulses with the aid of a delay network in the output circuit of one of these secondaries.

Abstract: A device for providing a voltage indicating the angular velocity of rotation of the armature in a limited rotation, polarized, moving iron galvanometer. The device includes a means for providing a first voltage dependent upon the angular velocity of the armature, the self-inductance of the galvanometer drive coil, and the drive current in the drive coil. A compensation coil is magnetically coupled to the drive coil and magnetically isolated from the effects of the rotating armature to provide a second voltage which is dependent upon mutual inductance between the drive and compensation coils and upon the drive current, but is not dependent upon the effects of the rotating armature due to the magnetic isolation of the compensation coil from the armature. A combining means proportionally combines the first and second voltages to provide a voltage indicating the angular velocity of rotation of the armature.

Abstract: A vibrator motor is coupled to the frame of a body support structure to vibrate the latter. The motor is energized by a train of triangular pulses modulated by a triangular pulse signal having a lower frequency than that of the triangular pulse train.