Apparatus for treating permanent magnets

Claim 2

Apparatus for reducing the magnetic intensity of a permanent magnet comprising: a. a main capacitor connected to a charging circuit; b. manually-operable means for adjusting the magnitude of the charging voltage applied to the capacitor; c. a pulldown coil connected to the capacitor through a discharge circuit which includes a first normally-open switch means; d. second switch means operable from normally-open to closed state upon the application thereto of a DC drive voltage of predetermined magnitude; e. means providing a DC drive voltage when the said capacitor is being charged; f. means applying said DC drive voltage to the said second switch means; g. adjustable means for varying the magnitude of the DC drive voltage applied to the second switch means; h. third switch means operable from normally-closed to open state for a predetermined time period when the second switch means changes from open to closed state; i. means closing the first switch means when the third switch means is in the closed state; j. fourth switch means operable from normally-open to closed state for a second predetermined time period when said third switch means changes from closed to open state; and k. control means opening the charging circuit when either the second, third or fourth switch means is in the closed state.

Claim 3

The invention as recited in claim 1, wherein the said charging circuit comprises an oscillator circuit consisting of a unijunction transistor having a capacitor and the primary winding of a pulse transformer connected in series across its'' emitter and base-one electrodes; a pair of secondary windings on the pulse transformer; a power transformer having a primary winding and a multitaped secondary winding, one end of said primary winding being connected to one side of an AC voltage source; a pair of silicon controlled rectifiers connected in opposite sense between the other end of the power transformer primary winding and the other side of the AC voltage source; leads connecting one secondary winding of the pulse transformer to the gate and cathode electrodes of the one silicon controlled rectifier; leads connecting the other secondary winding of the pulse transformer to the base and emitter electrodes of the other silicon controlled rectifier; and a full wave rectifier having input junctions connected between one end of the power transformer secondary winding and the said manually-operable means; said main capacitor being connected to the output junctions of the full wave rectifier.

Claim 4

The invention as recited in claim 2, wherein the said manually-operable means comprises a first rotatable switch having a movable contact connected to an input junction of said full wave rectifier and stationary contacts individually connected to the taps of the power transformer secondary winding.

Claim 5

The invention as recited in claim 3, wherein the said adjustable means comprises a second rotatable switch having a movable contact movable simultaneously with the movable contact of the first rotatable switch and stationary contacts corresponding to those of the first rotatable switch; a lead connecting the movable contact of said second rotary switch to one output junction of said full wave rectifier; fixed resistors connected across the stationary contacts of the second rotatable switch; a potentiometer connected in series between the said fixed resistors and the otheR output junction of the full wave rectifier; and leads applying the output voltage of said potentiometer to the said second switch means.

Claim 6

The invention as recited in claim 2, wherein the said second switch means comprises a Schmidt trigger providing a positive output voltage when in the closed stage, and wherein the said third switch means comprises a first one-shot multivibrator having its input circuit connected to the output circuit of said trigger through a second capacitor, said multivibrator providing a positive output voltage pulse when in the closed state.

Claim 7

The invention as recited in claim 5, wherein the said first switch means comprises a third silicon controlled rectifier connected between the negatively-charged terminal of said main capacitor and an end of said pulldown coil, and leads applying the positive output voltage pulse of said first multivibrator across the gate and cathode electrodes of the third silicon controlled rectifier.

Claim 8

The invention as recited in claim 6, including a rectifier diode connected in parallel with said third silicon controlled rectifier but in opposite sense.

Claim 9

The invention as recited in claim 5, wherein the said fourth switch means comprises a second one-shot multivibrator having its input circuit connected to the output circuit of the first multivibrator through a second capacitor, said second multivibrator being actuated to the closed state and providing a positive output voltage pulse for said second predetermined time period upon termination of the output voltage pulse of said first multivibrator.

Claim 10

The invention as recited in claim 5, including a normally nonconducting clamping transistor having its output circuit connected to the emitter and base-two electrodes of the unijunction transistor; and wherein the said control means comprises the said clamping transistor and circuit elements applying the positive output voltages of Schmidt trigger and the two multivibrators to the base of the clamping transistor.

Claim 11

The invention as recited in claim 9, including means to adjust the said second predetermined time period during which the second multivibrator remains in the closed state; a first switch; means maintaining the second multivibrator in the closed state when said first switch is in closed position; a third capacitor; a second switch movable between charge and discharge positions; means applying a charging voltage of predetermined magnitude to said third capacitor when said second switch is in the charge position; means discharging the third capacitor when the second switch is in the discharge position; and means switching the second multivibrator to the open state upon discharge of said third capacitor.

Claim 12

The invention as recited in claim 10, in combination with means producing a DC control voltage which varies in magnitude with the magnetic intensity of the permanent magnet; means producing a reference DC voltage of adjustable magnitude; a DC amplifier; circuit elements applying the said control voltage and reference voltage in opposed sense to the said amplifier; a fourth switch means actuated by the output voltage of said amplifier, said fourth switch means changing from normally-open to closed state when the amplifier output voltage has a predetermined magnitude; a generator producing a negative going output voltage of ramp waveform having a predetermined maximum magnitude; means for adjusting the slope of the generator output voltage; means applying the generator output voltage to the said adjustable means in a sense opposite to that of said DC drive voltage; means opening said charging circuit when the said fourth switch means is in the closed state; and means stopping operation of the generator when the said fourth switch means is in the closed state.

Claim 13

The invention as recited in claim 11, wherein said generator is an integrating amplifier having a capacitor and resistor connected in the feedback circuit and wherein said means stopping operation of the generator comPrises a sixth switch means actuatable from normally-open to closed state, means actuating said sixth switch means to the closed state when said fourth switch means is in the closed state, and circuit elements connecting the capacitor of the generator across said resistor when said sixth switch means is in the closed state.

Claim 14

The invention as recited in claim 11, including a first indicator providing a visual indication when the said fourth switch means is in the closed state; a fifth switch means actuated by the pulse generator output pulses, said fifth switch means changing from normally-open to closed state before such pulses reach the said predetermined maximum magnitude; and a second indicator providing a visual indication when said fifth switch means is in the closed state.

Claim 15

The invention as recited in claim 13, including a first power relay having a set of normally-open contacts; wherein the said fourth switch means is a first Schmidt trigger providing an output voltage when in the closed state, which output voltage energizes the operating coil of the relay; and wherein said first indicator is a lamp connected to a source of voltage through the said normally-open contacts.

Claim 16

The invention as recited in claim 14, including a second power relay having a set of normally-open contacts; wherein the said fifth switch means is a second Schmidt trigger providing an output voltage when in the closed state, which output voltage energizes the operating coil of the second relay; and wherein said second indicator is a second lamp connected to the source of voltage through the contacts of the second relay.

Claim 17

Apparatus for reducing the magnetic intensity of a permanent magnet positioned within a pulldown coil, said apparatus comprising: a. a pulse transformer having a primary winding and a pair of secondary windings; b. an oscillator circuit which includes the pulse transformer primary winding and a unijunction transistor; c. a normally nonconducting clamping transistor having its output circuit connected to the emitter and base electrodes of said unijunction transistor, said transistor conducting when a positive voltage is applied to the base thereof; d. a power transformer having a primary winding connected to a source of AC voltage, through a pair of silicon controlled rectifiers arranged in opposed sense, said transformer having a multitaped secondary winding; e. circuit elements connecting the gate and anode electrodes of each silicon controlled rectifier to one of the pulse transformer secondary windings; f. a full wave rectifier having one input junction connected to an end of the power transformer secondary winding; g. a first switch having a movable contact connected to the other input junction of the said rectifier and stationary contacts connected to the taps of the multitaped secondary winding; h. a first capacitor connected across the output junctions of said rectifier; i. circuit elements connecting the pulldown coil across the first capacitor through a third silicon controlled rectifier; j. a second switch having a movable arm connected to the positive output junction of said rectifier and a plurality of stationary contacts corresponding in number to those of the said first switch; k. fixed resistors connected across the stationary contacts of the second switch; l. a potentiometer connected to the output junctions of said rectifier through the fixed resistors; m. a first Schmidt trigger actuated by the output voltage of said potentiometer and providing a positive output voltage when in the triggered state; n. means applying the trigger output voltage to the base of the said clamping transistor; o. a first one-shot multivibrator actuated by the output voltage of the first Schmidt trigger, said multivibrator providing a first positive output voltage pulse of predetermined time duration; p. circuit elements applying said first output voltage pulse to the base of said clamping transistor and across the gate and anode electrodes of said third silicon controlled rectifier; g. a second one-shot multivibrator actuated upon termination of the said first voltage pulse, said multivibrator providing a second positive output voltage pulse of predetermined time duration; r. means for varying the time duration of said second output voltage pulse; and s. circuit elements applying said second output voltage pulse to the base of said clamping transistor.

Claim 18

Apparatus for reducing the magnetic intensity of a permanent magnet positioned within a pulldown coil, said apparatus comprising: a. a pulse transformer having a primary winding and a pair of secondary windings; b. an oscillator circuit which includes the pulse transformer primary winding and a unijunction transistor; c. a normally nonconducting clamping transistor having its output circuit connected to the emitter and base electrodes of said unijunction transistor, said transistor conducting when a positive voltage is applied to the base thereof; d. a power transformer having a primary winding connected to a source of AC voltage, through a pair of silicon controlled rectifiers arranged in opposed sense, said transformer having a multitaped secondary winding; e. circuit elements connecting the gate and anode electrodes of each silicon controlled rectifier to one of the pulse transformer secondary windings; f. a full wave rectifier having one input junction connected to an end of the power transformer secondary winding; g. a first switch having a movable contact connected to the other input junction of the said rectifier and stationary contacts connected to the taps of the multitaped secondary winding; h. a first capacitor connected across the output junctions of said rectifier; i. circuit elements connecting the pulldown coil across the first capacitor through a third silicon controlled rectifier; j. a second switch having a movable arm connected to the positive output junction of said rectifier and a plurality of stationary contacts corresponding in number to those of the said first switch; k. fixed resistors connected across the stationary contacts of the second switch; l. a potentiometer connected to the output junctions of said rectifier through the fixed resistors; m. a first Schmidt trigger actuated by the output voltage of said potentiometer and providing a positive output voltage when in the triggered state; n. means applying the trigger output voltage to the base of the said clamping transistor; o. a first one-shot multivibrator actuated by the output voltage of the first Schmidt trigger, said multivibrator providing a first positive output voltage pulse of predetermined time duration; p. circuit elements applying said first output voltage pulse to the base of said clamping transistor and across the gate and anode electrodes of said third silicon controlled rectifier; g. a second one-shot multivibrator actuated upon termination of the said first voltage pulse, said multivibrator providing a second positive output voltage pulse of predetermined time duration; r. means for varying the time duration of said second output voltage pulse; and s. circuit elements applying said second output voltage pulse to the base of said clamping transistor.

Claim 19

The invention as recited in claim 16, including a third switch; means actuating said second multivibrator to the closed state when the third switch is in the closed position; a second capacitor; a fourth switch movable between first and second positions; means charging the second capacitor when the fourth switch is in the first position; means discharging the second capacitor when the fourth switch is in the second position; and means actuating the second multivibrator to the normal open state upon discharge of the second capacitor.

Claim 20

The invention as recited in claim 16, in combination with: a. means producing a DC control voltage which varies in magnitude with the intensity of said permanent magnet; b. an adjustable source of DC reference voltage; c. a DC amplifier; d. circuit elements applying the control and reference voltages to the amplifier in opposed sense; e. a second Schmidt trigger actuated by the output voltage of said amplifier and providing a positive output voltage when in the triggered state; f. circuit elements applying the output voltage of said second trigger to the base of said clamping transistor; g. an integrating amplifier having a capacitor and resistor connected in series in the feedback circuit, said amplifier producing negative output voltage pulses of ramp waveform; h. means for adjusting the slope of the said negative output voltage pulses; i. circuit elements applying said negative output voltage pulses into the output circuit of the said potentiometer; j. a third Schmidt trigger actuated by the output voltage pulses of the integrating amplifier when said pulses reach a predetermined magnitude; k. a clamping circuit comprising a pair of normally nonconducting transistors, said transistors having output circuits connected respectively across the capacitor and resistor of the integrating amplifier; and l. circuit elements applying the output voltage of said second Schmidt trigger to the transistors of said clamping circuit, whereby these transistors become conducting and effect a discharge of the second capacitor through the resistor.

Claim 21

The invention as recited in claim 18, including a first indicator providing a visual indication when said second Schmidt trigger is in the triggered state; and a second indicator providing a visual indication when said third Schmidt trigger is in the triggered state.