US2396497A - Timing control circuit - Google Patents

Description

March 12, 1946. B. EISENBERG 2,396,497

TIMING CONTROL CIRCUIT Filed Sept. 27, 1941 CURRENT METER TIMER 6 LIMITER 7 8 2W /3 (P (P (19 C (P 0d 1 I l I L ru// 5 4 (Electrodes INVENTOR 5+ BEN EISENBERG ATTO R N EY tailed desc iption. in which 'ure 1.

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Patented Mar. 12, 1946 TIMING CONTROL CIRCUIT Ben Eisenberg, Brooklyn, N. Y., assignor to Lektra Laboratories, Inc., New York, N. Y. a corporation of New York Application September 27, 1941, Serial No. 412,644

7 Claims.

.This invention relates to the art including elect tronic circuits useful for the precisely timed control of the action of controlled devices, and more particularly to such circuits for energizing or deenergising a controlled device for predetermined precise intervals or time.

A typical application of the present invention is in the held of electric shock therapy, and it will be described with respect to such an application, although in no way restricted thereto.

vide improved timing circuits, especially adapted I for, but not restricted to, electric shock therapy, which will eiiect a predetermined operation for an accurately defined and easily controllable time interval. I

It is a further object of the present invention to prcvide'such improved timlni' circuits in which sharp and positive energizati'on and de-energization or a relay is eilected'by a simple circuit by which the commencement oi enetsization (or dc-sncrgisation, as the case may he) acts to increase the cnersisation (or de-energisation) so that the only stable condition thereatter is that of complete energization '(or deg-energization) which is attained in a very short time.

Further objects and advantages of the presentof my electric shock therapy device, which are adapted to be connected to any suitable source of alternating current, such as the conventional alternating power supply. Connected to terminals I, through a power switch 2, is a. voltage adjusting device illustrated as being a variable auto-transformer by means or which the voltage to be applied to the patient may be adjusted to the proper value as determined by diagnosis and measurement. Any suitable voltage adjusting means may he used here. This voltage may be measured by voltmeter 4. I

Connected across the adjusted voltage output oi the voltage regulator I is a series circuit comprising a current limiter 6, a current meter 1, a timer I and the applying electrodes is, connected in this circuit by the throw-over switch 9, when in the right-hand position.

When switch 8 is thrown to the lert, or "test" go position, the electrodes 13 are connected through a resistance meter II, which may be of any coninvention will be apparent from the ioilowing dethe invention is em,- bodied in concrete term. n f

In the drawing.

Figure 1 shows a schcmatic wiring dianam or" in which the. i

anelectric shock therapy device present invention may be used. I

Ilsure 2 shows a schematic wiring diagram of the current-pulse meter or the device 0! F18- Maura shows a schematic wiring diagram oi form of timing circuit according to themes- 1 ant invention. suitable ior use withthe circuit oi Fi ure 1:

, Iigure 4 showsa schematic wiring diagram oi modification o! the-circuit 0! Figure 3,

Idea-ing to the drawin in lime 1, referonce numeral i represents the input terminals ventional type, to a suitable source of direct voltage, indicated by terminals l2. Switch 9 also has an open position, in which electrodes I: are

.35 completely disconnected rom the rest of the apparatus.

Current limiter i may be any suitable device which will ins re that the maximum current delivered to the patient through the applying electrodes it does not exceed a-saie value. In a preferred embodiment, this current limiter 6 may take the form or an adjustable current-operated circuit breaker which may beset to a value just exceeding the described current dose.

Current meter I is used to give the operator a direct and instantaneous indication of the amount of current administered to the patient. For this purpose a special circuit is necessary,

- because oi. the relatively short duration of ap-' plied current, whichlasts-only tor a time interval of the order oi one-tenth of one second. 2 shows a suitable circuit for such a current meter.

Input terminals (1-42 0! meter 1 are connected to the primary winding ll 01 a current transformer il whose secondary winding is is connected through condensers :4, 25 across double diode 23, whose two diode sections are connected in parallel to provide a low impedance load for transformer Il. Any diode or sumciently low impedance'may be used in place of doublediode 2,3. In order that the meter as a whole shall ofler as low an impedance as possible to the applied current. the primary winding 11 or transformer I! is shunted bya resistor it having a very low resistance value which may be of the order or 5 ohms. I I

In order that transient pulses caused by opening or closing of line switch .2 or by conditions on the line I shall not adversely affect the indication of meter 1, the secondary winding IQ of transformer I8 is shunted by a condenser 2i which provides a low impedance path for the transient impulses, which are being almost entirely of relatively high frequencies.

Since the current pulses to be measured are of quite small duration, it is essential that the indication of meter 1 be given without appreciable lag. Also, the indication must be maintained for a reasonable length of time after the initiation of the current in order that the reading may be conveniently made. These two requirements are in a sense contradictory, since, ingeneral, a circuit which responds quickly cannot maintain its condition for any length of time. For a quick response, it is necessary that the load circuit of the transformer l8 be of low time constant. on

' the other hand, the requirement that the circuit condition he maintained until a good reading can be obtained requires a rather high time constant. The circuit of Fig. 2 is especially designed to overcome this apparent contradiction.

In order that the circuit shall respond quickly, the time constant of the load circuit of diode 23 is made small by using no load resistor and a small capacitance, derived from the series connection of condensers 24 and 28. Of these condensers, condenser 24 is chosen with fairly small capacitance, and condenser 28 with rather high capacitance. Hence, their series connection will have small capacitance, permitting a low time constant as is desired.

To obtain a maintained meter reading. the voltage across .the condenser 28 is used. Because oi the high capacitance of condenser 28, its voltage will be held practically constant substantially without decaying, for an appreciable time, sutilcient to obtain the desired reading, it connected to a high resistance circuit. Accordingly, one terminal of condenser 28 is grounded as at 21, and the other is connected to the control grid 33 of one section of a double triode tube 82, through a resistor 3!. The time constant of the output circuit of the diode 23 is determined by condenser 28 (already of high capacitance) together with resistance 3| and'the grid resistance of tube 32. Switches 28 and, 29 are provided to discharge condensers 24 and 28 after the reading has been obtained. ,These switches are necessitated by the high time constant of the circuit ofcondenser 28, which maintains the voltage on condenser 28 for a substantial time. Switches 28 and 28 may be ganged, asshowm- Double trlode' 32, which may be replaced by any pair of similar amplifying tubes, and its associated circuit elements act as a bridge type electronic voltmeter to measure the voltage across condenser 28. The four arms of this bridge circuit are formed respectively by the two sections of tube 32 and two resistors 43 and 44, which are the load resistors for the two tube sections, meter 41 being connected directlyirom plate to plate of the two tube sections. Resistor 44 is made adjustable.

The two cathode 38 are connected direct- 1y together, and to ground through their common biasing resistor 4|. The control grid 34 of the second triode section is also connected to ground, through the grid leak resistor 42. The common terminal of resistors 43, 44 is connected to the positive terminal of a suitable source of direct voltage, whose negative terminal is grounded.

In operation, switches 28 and 28 are momentarily closed and then reopened. Then, with zero input to transformer l8, the bridge is balanced by adjusting variable resistor 44, until the meter reading is zero, whereupon the bridge is in balanced condition. Then any current passing through the primary winding of transformer I 8 will produce a corresponding and proportional direct voltage across condenser 28, which voltage will persist for a substantial period because of the high time constant of the output circuit of diode 23. This voltage will produce an unbalance in the meter bridge arrangement, by causing the current in arm 44 to change, so that a definite indication is produced on meter 41, which will persist long after the initiating current pulse is over. Thus the present arrangement provides a sensitive current meter for measuring even rather short current pulses, as are met with in devices of the present type.

Figure 3 shows the schematic wiring diagram of one type of timing circuit incorporating the present invention and suitable for use as the timer 8 of Figure 1. This timing circuit comprises two electron discharge tubes, 82 and 82 shown, for illustrative purposes only, as being a pentode 52 and a beam-power tube 82. As will be more evident later, any types of known amplifler tubes may be used in place of tubes 82 and 82.

Power is supplied to the circuit by way of a voltage divider composed of resistors 82 to 88 connected in series across any suitable source of direct voltage, indicated schematically by positive terminal 18, the negative terminal being grounded as at 49. Cathode 51 of tube 82 is connected to the junction of resistors 83 and 84, while control grid 58 is connected to the junction of resistors 82 and 83, through variable resistor 18, so that the volt-drop across resistor 83 provides a fixed or normal grid bias for tube 82, sub- Ject to the changes described below. Condenser 8i has one terminal connected also to the junction of resistors 82 and 83, while the other terminal is selectively connectible to ground 48 or to grid 88, according as switch is thrown to position A or to position-B. Hence, in position A of switch 88. condenser 8| is charged up to the voltdrop appearing across resistor 82, while in position B it discharges through resistor 18, thereby adding a variable decaying control voltage in series with the fixed bias provided by resistor 83 for grid 88.

The anode 53 of tube 52 is energized by con nection through load resistor 81 to the Junction of resistors 84 and 85, while screen grid 84 is connected directly to the junction of resistors 88 and, and is therefore .at a higher potential than that of anode 53.

Control grid 81 of tube 82 is connected directly to anode 63 and to one terminal of load resistor 8'! by means of conductor 88, while the cathode 88 of tube 82 is connected to the other terminal of resistor 81 by means of conductor 4|,

so that the full volt-drop across resistor .forms I the input voltage to tube 82.

\ v Screen grid 88 and anode 83 of tube 82 are connected directly together, and both are connected to terminal 18 through relay winding 13, which forms the load impedance i'or tube 82, Winding 13, when energized by the flow or anode current through tube 82, draws its magnetic armature 14 against fixed contact 18, thereby completing the control circuit c-d for electrodes l8, or for any other control circuit, represented by conductors 11.

In operation, switch 58 is normally left in positionA. Resistor 88 is so chosen that the normal plate current of tube 82 flowing in resistor 81 will produce a normal volt-drop suflicient to bias tube 82, to at least the cut-oi! point. Ac-

cordingly, no plate current flows to anode 83, and

' ing the plate current flowing through resistor 81. Therefore the volt-drop across resistor 81 is reduced, decreasing the negative biason grid 61. Preferably, the increased bias on grid 58 biases tube 52 beyond cut-off, so that zero voltage remains across resistor 81, and tube 62 begins to conduct at once, energizing relay 13. However, cut-oil bias is not necessary.

As soon as plate current begins to flow in tube 82, the volt-drops across resistors 82, 83 and 84 increase, due to the added current flowing therein because of the conductive state of tube 82. The increased voltage across resistor 83 (which is common to the input circuit of control tube 52 and to the output circuit oi power tube 62) due to this increased current drives tube 52 further towards cut-ofi (if not" already there), thereby causing increased current flow through resistor 88. Hence the action is cumulative, causing tube 82 to change rapidly from zero conduction to full conduction and energizing relay 13 almost instantaneously.

Relay I3 is maintained energized so long as the sum of the volt-drops across resistors 18 and 88 exceeds the cut-off voltage or tube 52. However, condenser 8| gradually becomes discharged through resistor 18, whose volt-drop therefore decreases with time. drop sum becomes less than the cut-off voltage, the reverse sequence of operations is effected, whereby relay 13 becomes instantly de-energized.

Hence, the time interval during which relay 13 remains energized depends directly upon the discharge rate of condenser 8|. This may be adjusted by adjusting the resistance of variable resistor 18, thus affording a sensitive and accurate control of the time interval of energiz ation.v

It will be clear that the present timing circuit is not restricted in its use to the particular one shown, but may be used wherever it is desirable to close a circuit for an accurately adjustable time interval. Also, by slight changes in the disposition of armatur 14 or by the addition or other contacts and contact 18, many other uses may be round for this circuit. Typical other uses may be for such applications as timing exposures in pho-'- tographic printing, or in timing X-ray treatments.

Switch 58 may be made asa momentary contact switch, normally in positionA, but which may be held in position B. Then, in operation, the operator holds the switch in position B until treatment is completed and then releases the switch, thereby automatically recharging condenser 8|, in preparation for the next treatment. Thus, full control of treatment is in the operators hands, and may be terminated at any time. This provides an additional safety feature. by releasin At the instant that the volt- 4 switch 88 to position A. so that tube 82 is blocked and the relay 13 is released at once to terminate the treatment.

Figure 4 shows a modification of the circuit of Figure 3. This circuit is generally the same as that of Figure 3, except that screen grid 54 of tube 52 is here connected to cathode 51, load resistor 81 is removed. and beam-power tube 62 ha been replaced by an ordinary tetrode 84, whose screen grid 82 is connected to its cathode 8|. The remainder of the elements and connections are the same as in Figure 3.

The operation of this circuit is believed to be as follows: With switch 58 in position A, the interelectrode capacitances of tubes 94 and 52 cause grid 89 to assume a potential intermediate to those 0! cathodes 51 and 8|, thereby driving tube 94 to cut-off. Throwing switch 58 to position B dis turbs the equilibrium potential'oi grid 89, which is connected directly to the anode of tube 52, and causes tube 94 to start conducting, This sets into play the same cumulative action described above, and relay 13 becomes instantly energized. After condenser 8| has discharged to the proper degree,

i the potential of grid 89 seems to change in the negative direction, and the reverse cumulative action occurs, instantly tie-energizing relay 13. The time interval of energization is again directly responsiv to the adjustment of variable resistor 18.

Having described the various components of the system in detail, the operation of the electric shock therapy apparatus will now be described. Switches 2 and 8 are normally left in the open position, and switch 58 is left in position A. Electrodes |3 are placed ingood electrical contact with chosen portions of the patients head. Then switch 8 is thrown to the left, or test position, and the patient's electrical resistance is measured on resistance meter H. The reading thus obtained will inform the operator as to the proper adjustment of voltage adjuster 3 and the proper shock duration necessary to obtain the desired treatment. Voltage adjuster 8 and rheostat 19 of timer 8 are then set to the proper values, switch 2 is closed, and switch 8 is thrown to the right, or treat position. Then switch 58 is thrown to position B, whereupon treatment is at once initiated, and automatically stops after. the time interval adjusted for. After treatment is completed, switch 58 must be thrown again to posi tion A, so that condenser 8| may be recharged, before further treatment can be given.

Since many changes and modifications could be i made in the devices disclosed above without departing from the spirit of my invention, the present description is to be in no way considered in a limiting sense, but merely as illustrative of the invention pointed out more particularly in the appended claims.

I claim:

1. A control circuit comprising a relay, an electron discharge tube, means connecting said relay in the output circuit of said tube. a second electron discharge tube, means directly connecting the output of said second tube to the input of said first tube, means for adjusting the normal plate current of said second tube to such a value that said first tube is blocked, whereby said relay is unenergized, means for momentarily blocking said second tube, whereby said normal plate current drops to zero and said relay becomes energized, and means responsive to flow of current thru said relay for maintaining said second tube blocked. said last. twn means comprisin a. re-

sistor connected in the output circuit of said first tube, a source of control voltage. and means connectlng both said source and said resistor to said second tube input, whereby said second tube input is responsive to both said control voltage and the volt-drop across said resistor.

. 2. A control circuit comprising a power tube, a relay connected in the output circuit of said power tube, a control tube having an output resistor, means for connecting the volt drop across said output resistor in direct current fashion in the input circuit of said power tube,- a resistor common to the input circuit of said control tube and the output circuit of said power tube, means for producing a normal volt drop across said resistor suflicient to bias said control tube to a value pro-- ducing a volt-drop across said output resistor suificient to bias said power tube beyond cut-oil, and means for applying a varying control voltage to the input circuit of said control tube in series with the voltage drop across said resistor, said voltage having an initial value suilicient to overcome said normal volt-drop and block said control tube, said voltag thereafter decaying with time, whereby said control tube is initially rendered non-conductive so as to unblock said power tube and to cause current to flow through said relay and said resistor, said current thereby further blocking said control tube to maintain said relay in energized condition until decay of said voltage to a value producing less than the cut-off bias for said control tube, whereupon said control tube is then rendered conductive to block said power tube and decrease said. resistor current to further unblock said control tube and immediately de-energize said relay, whereby said relay is energized only for a period determined by the decay of said voltage.

3. A control circuit comprising a power tube having a relay connected in the output circuit thereof, a control tube having an output resistor connected between the anode thereof and a source of positive voltage and a screen grid connected to a source of higher positive voltage, means connecting said resistor in the input circuit of said power tube, a resistor common to the input circuit of said control tube and the output circuit or said power tube and adapted to decrease the conductivity of said control tube in response to increased current flow through said power tube and relayo and means for applying a decaying voltage in series with the volt-drop across said common resistor to momentarily block said control tube, whereby said relay is energized for the time interval required for said voltage to decay to a value unblocking said control tube.

4. A control circuit as in claim 1, wherein said source comprises means for producing a decaying control voltage whereby said second tube is essentially blocked by said voltage and volt-drop an becomes unblocked after a time interval necessary for said voltage to decay to a predetermined value so that said relay current flows only for said time interval.

5. A control circuit'as in claim 1, further including means for disconnecting said source from.

said control tube input circuit, whereby said relay current may be manually interrupted as desired.

6. A control circuit comprising a relay, an electron-discharge tube, means connecting said relay in the output circuit of said tube, a second electron-discharge tube, means directly connecting the output of said second tube to the input of said first tube, means for adjusting the normal plate current of said second tube to such a value that said first tube is blocked, whereby said relay is unenergized, means for momentarily blocking said second tube, whereby said normal plate current drops to zero and said relay becomes energized, and means responsive to flow of current through said relay for maintaining said second tube blocked, said last-named means including a resistor common to the input circuit of said second tube and to the output circuit of said first tube.

7. A control circuit comprising a relay, an electron-discharge tube, means connecting said relay in the output circuit of said tube, a second electron-discharge tube, means directly connecting the output of said second tube to the input of said first tube, means for adjusting the normal plate current of said second tube to such a value that said first tube is blocked, whereby said relay is unenergized, means for momentarily blocking said second tube, whereby said normal plate current drops to zero and said relay become energized, and means responsive to flow of current through said relay for maintaining said second tube,' blocked, and further including means for unblockin: said second tube after a predetermined time interval, and means responsive to said unblocking for further unblocking said second tube.

' BEN EISENBERG.

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