US2749125A - Target indicating apparatus - Google Patents

Description

June 5, 1956 D. F. REAM 2,749,125

TARGET INDICATING APPARATUS F IG. 2.

I N VENTOR i DONALD F. REAM BY 1M, fl wlih ATTORNEYS Unite This invention relates to a target indicating apparatus and has particular utility in dueling courses of fire for indicating which one of a plurality of targets has been struck first.

In the type of target practice known as dueling, a number of contestants are involved, there being a separate target for each contestant. Upon receipt of the signal to tire, each contestant must draw, aim and fire at his specified target as quickly as possible, the winner of the contest being the one who hits his specified target first. As the proficiency of the contestants increases, the difference between them in the time taken to draw, aim and fire becomes less and less,,with a consequent increase in the difficulty of ascertaining which one of the targets was struck first. Heretofore, it has been the practice to employ, in some instances, mechanical means for determining which target'was struck first. The inaccuracies of such means stem from the time lags inherent in any me- 'chanical system and, in addition, in most mechanical systems, the judgment of the referee in determining which target actuated its mechanical system first. Other indicating systems have been evolved which involve the use of individual lights or buzzers for each target, the light being either turned on or off or a buzzer sounded when its target is struck. Such a system, while usually faster acting than the mechanical type, is basically inaccurate because of the time lag in the filaments of the lamp or the inertia of the buzzer striker and, usually, the judgment of the referee. In practically all dueling target indicator sys tems, there is the basic problem created by the targets being located at a considerable distance from the contes'tants and the referee, with the consequent difliculty of transmitting the indication from the targets to the referee.

It is an object of this invention to provide a target indicating apparatus capable of giving an exceedingly accurate indication of when a specific target has been struck.

It is a further object of this invention to provide a target indicating apparatus which completely eliminates the element of human judgment in determining which one of a number of targets was struck first. Another object of this invention is to provide a target indicating apparatus, the indicator portion of which may be located at any reasonable distance from the target without impairing the accuracy or operation of the system.

Still another object of this invention is to provide a target indicating apparatus which is simple and efiicient in operation and easy to maintain in proper working condition.

Still further objects and advantages of this invention will be readily apparent from the following specification taken in conjunction with the drawings in which Fig. 1 is a schematic wiring diagram of a target indicating apparatus embodying the present invention, and

Fig. 2 is aside elevation view of a portion of one of the targets'showing a projectile passing therethrough.

In accomplishing the aims and objects of this invention, I provide a target indicating system providing a plurality of targets, usually two, and a control and indicating eleat s Paten locked out like.

,. ice

meat capable of being placed at a location remote from the targets. Each target is of the general type shown and described in U. S. Patent 474,109 and consists of two electrically conductive plates or screens separated by dielectric material of a thickness somewhat less than the length of the bullet or projectile used in target practice. A D. C. voltage is impressed across the plates of the target so that the target acts as a large condenser.

When a bullet pierces the target, the two plates will be momentariiy short-circuited and the charge dissipated, thereby creating a very high frequency discharge pulse. If the indicating element or unit is at a distance remote from the target and connected thereto by any sort of standard cable, the. high frequency pulse will be so greatly attenuated as to be practically useless as a signal. However, after the plates of the target are discharged, they will start to charge again as soon as the short circuit is removed, i. e., the projectile leaves the target. The charging current is of a much longer time base than the discharge pulse, and, consequently, is not attenuated to any great degree by the connecting cable. By placing the primary of a transformer in series between one plate of the target and the power supply, I obtain a large, positive voltage pulse in the secondary due to the charging current in the primary. This positive voltage pulse is fed to the starter electrode or grid of a cold cathode, gas discharge tube, and is of sufiicient magnitude to ignite the tube.

In series with the plate circuit of the tube is the coil of a fast acting relay, the normally closed contacts of which are in series with the plate circuit of a second gas discharge tube, identical to the first, which is in the circuit of the second target. Plate current in the first tube will actuate the fast acting relay, opening the plate circuit of the second tube and preventing it from firing, leaving only the first tube ignited, regardless of a subsequent hit on the second target. By providing identical transformers and tube circuits for each target, it will be apparent that whichever target is struck first will ignite its corresponding gas tube first, thereby locking out all other tubes. It is obvious that any suitable switch means may be used which will act to lock out the other tubes, but by proper proportioning of the elements, and by use of fast acting relays, I have found that my indicating circuit will accurately indicate which target is struck first even though a subsequent hit may be made on another target less than one millisecond later. 'It is obvious that having once the other circuits, any suitable means may be used to "visually indicate which target was struck first. In the embodiment here'shown, I-use the cold cathode tube itself, inasmuch as tubes of this type -glow intensely when ignited, thus affording a clear visual indication to the referee.

Turning now to the drawings, I have shown my invention in an embodiment utilizing two identical targets, 10 and 11, target 1%? having two electrodes of electrical conducting material 12 and 14, separated by a suitable dielectric material 16. In a like manner, target 11 has electrodes 13 and 15, separated by dielectric 17. In order to supply a potential difference to the plates of the targets, any suitable D. C. source may be used. In the embodiment shown I use a standard dry cell battery 18 of approximately volts, the terminals of which are connected to a voltage divider network comprising resistors 19, 20, 21 and 22. A portion of the voltage across the divider is fed through leads 24 and 26 to the terminals 28 and 30, to which is connected cable 32, which may be any standard cable, such as a twisted pair or the The wires at the other end of cable 32 are connected to the target electrodes 12 and 14 as shown, resistor 34'being connected across the electrodes to maintain the potential difference therebetweem In a like manner, the same .voltage'is fed through leads 23 and 25 to the terminals 27 and 29 which are connected to cable 31, the wires 'of which are connected to target electrodes 13 and as shown. Resistor 33 is connected across the electrodes to maintain the potential difference therebetween. In series with each other in the positive lead 26 between the voltage divider and terminal 3%) are the primary coil 36 of a transformer T2 and a normally closed push button switch 38, the purpose of which will be explained hereinafter. In like manner, in series with positive lead are the primary coil of transformer T1 and a normally closed push button switch 37. The secondary coil of transformer T2 is connected at one end to the grid or starter electrode 42 of a gas discharge tube V2 and at its other end through resistance 44 to lead 26 at a point 46 between switch 38 and primary coil 36. The cathode 48 of tube V2 is connected through loads and 52 to negative lead 24. Secondary coil 39 of transformer Tlis connected at one end thereof to the grid or starter electrode 41 of gas discharge tube V1 and its other end is connected through resistance 43 to lead '25 at a point 45 between switch 37 and primary coil .35. The cathode 47 of tube V1 is connected through leads 49 and 52 to the negative lead 24. The plate 54 of tube V2 is connected through lead 56 to a coil 58 of a relay Rel. 2, resistor 60, contacts 62 of a relay Rel. 1 to juncture 64. The juncture 64 is connected through lead 66 to the positive side of the power supply 18 as best seen in Fig. 1. A switch 68 is connected in series between juncture 64 and the positive side of the power supply. The plate 53 of tube V1 is connected through lead to the coil 57 of a relay Rel. 1, through a resistor 59, contacts 61 of relay Rel. 2 and juncture point 64. It will be apparent that when switch 68 and contacts 61 and 62 are closed that both tubes V1 and V2 will have a positive voltage impressed upon their plates. In parallel with coil 58 of the relay Rel. 2, there is connected a potentiometer comprising resistance 70 and arm 72. In like manner, a potentiometer comprising resistance 69 and arm 71 is connected in parallel with coil 57 of relay Rel. 1. Arms 71 and 72 are mechanically coupled together in such a manner that movement of arm 71 to increase the resistance 69 will result in movement of arm 72 in a direction to decrease the resistance of 70. The reason for this arrangement will be explained hereinafter. In parallel with resistance is a capacitor 74 and in parallel with resistor 59 is a capacitor 73. The function of resistance 60 and capacitor 74 is to increase the speed'of operation of relay Rel. 2 in a manner prescribed by the manufacturers of such fast acting relays, and it is to be understood that they form no part of this invention. In like manner, the purpose of resistor 59 andcapacitor 73 is to increase the speed of operation of relay Rel. 1.

Having described the circuitry of my device, I will now explain the operation thereof. When battery 18 is connected into the circuit, the voltage output of the battery will be divided by voltage divider network 19, 20, 21 and 22, and a portion of that voltage will be impressed across the target electrodes 12 and 14 and 13 and 15. When switch 68 is closed, a positive voltage will be impressed on the plates of tubes V1 and V2 the contacts of relays Rel. 1 and Rel. 2 being normally closed. Assuming now that a bullet'strikes target 10 before a bullet strikes target 11, at the instant the bullet reaches the position shown in Fig. 2 the electrodes 12 and 14 will be shorted together and :the potential difference between them will .be dissipated. It will be apparent that if the spacing between the plates 12 and 14 is approximately; inch and a bullet 95. inch in length and traveling at approximately 2,000 feet per second strikes the target, thelength of time that the plates 12 and 14 are connected togetherrbythe bullet will be on theorder of 10 microseconds. vThis timeinterval is sufficient for the charge on theplates12 and 14 to be largely dissipated. This .dischargeiresults in a high frequency pulsehaving a time base of approximately 10 microseconds, which will be -rapidly attenuated in the cable 32. After the projectile has ceased to short electrodes 12 and 14 to gether, the power supply will act to charge the plates again through the voltage divider network, resulting in a momentary surge of charging current of a much longer time base than the discharge pulse. This charging current, in passing through coil 36 of transformer T2 will act to impress through secondary 40 a positive voltage on grid 42 of sufiicient magnitude and duration to fire tubc V2. The plate current of tube V2 will then flow from the positive side of power supply 18, through switch 68, lead 66, junction 64, contacts 62, resistor 60, coil 58, and lead 56, through the tube, lead 50, and lead 52 to the negative side of the power supply. Coil 58 of relay Rel. 2 will be energized by this plate current and contacts 61 will be opened. Inasmuch as the plate circuit of tube V1 includes contacts 61, when these contacts are open, the positive voltage impressed upon the plate 53 of tube V1 will be removed, and V1 will be inoperative. Inasmuch as the response time of relays Rel. 1 and Rel. 2 is of the order of V of a millisecond, it will be readily apparent that a bullet striking target 11 approximately 55 of a millisecond after a bullet struck target Etl will not act to fire tube V1. Any suitable means might be used to indicate that tube V2 has been ignited due to target 10 being struck first. In practice, I have found that the glow of the tubes V1 and V2 is sutficiently strong to be readily perceptible to the naked eye and thus the tube itself may act as the indicator. After the referee has recorded the results, he opens switch 68, removing the positive voltage from the plates of both tubes V1 and V2, and extinguishes the tube that is firing When switch 68 is closed, the circuit is in condition to indicate the next dueling course. If target 11 had been struck first instead of target 10, the operation would have been identical except that tube V1 would have been ignited and relay Rel. 1 activated, opening contacts 62 and locking out tube V2. In the event that both targets are struck in less than approximately 1 of a millisecond, both tubes V1 and V2 will be ignited momentarily and be extinguished as both re lays Rel. 1 and Re]. 2 will be activated, opening the plate circuits of both tubes. Thus, if the referee sees both tubes ignite and then go out, he will record the results as a tie. In order that there will be no interchange of energy between targets 10 and 11 when one of the targets is struck, I provide a capacitor 76 connected across the output of the voltage divider to the targets, to maintain a stable D. C. potential across the target electrodes 12, 14 and 13, 15. Due to the use of capacitor 76, the voltage distribution across the voltage divider network 19, 20, 21, 22 remains substantially constant at all times. even during the recharging period following the discharge of the target plates by a projectile. Upon the discharge of either target by passage of a projectile, capacitor 76 provides substantially all of the recharging current for the discharged target, capacitor 76 itself being recharged through the voltage divider network following the actuation of indicating tube V1 or V2. The time required to recharge capacitor 76 is substantially a function of the R-C time constant of capacitor 76 and the parallel connected arms 20 and 22 of the voltage divider under normal operating conditions, assuming switch 78 to be closed. Any redistribution of voltages across the voltage divider network in connection with the recharging of capacitor 76 is negligibleand is not sutficient to produce any significant effect on the targets or on their associated indicator circuits. In addition, capacitor 76 reduces the A. C. impedance of the voltage divider so that the charging'cm'rent will be a maximum.

It is apparent that a difference in the speed of action. between the combinations Tl, V1 and Rel. 1 and T2, V2'and Re]. 2 will weigh the results of near-simultaneous target hits in favor of one target and against the other.

In order that these action times may be balanced, I have provided the potentiometers 70, 72 and 69, 71 in shunt with the relay coils 58 and 57, respectively. Since the action time of the relays is approximately proportional to the current through their coils, movement of arm 72 in a given direction will increase the time of action of the circuit combination of T2, V2 and Rel. 2 and at the same time decrease, through the mechanical connection to arm 71, the action time of the circuit of T1, V1 and Rel. 1. By connecting the two sets of target terminals in parallel and shorting one set such as 28, 30, a simultaneous hit on each target is simulated and the potentiometers may be adjusted until such simultaneous hit results in a momentary flashing and then extinguishing of both tubes J1 and V2.

When the circuit, targets and cables are connected, there is need for an indicator to show that the leads to the targets and the targets themselves are not inadvertently shorted and also to show that the target leads are continuous and not open. Also, there is need within the circuit for a voltage meter which shows the condition of the battery. All of these conditions can be shown on a meter M1 of the milliammeter type when connected in one arm of the voltage divider network as shown in Fig. 1. A switch 78 is connected into the voltage divider network between the junction points of resistors 19, 20 and resistors 21, 22 for a purpose which will be explained hereinafter. When the leads to the targets are continuous and neither the leads nor the targets are shorted, there is a complete circuit from the battery to the targets, through resistors 33 and 34, and back to the battery, and the meter is adjusted to indicate approximately 0.5 full scale. Thereafter, if the leads to either or both targets be open, the meter will read well above 0.5 full scale. If either of the targets or the leads be shorted, the meter will read well below 0.5 full scale. Opening switch 78 will have the effect of converting the milliammeter M1 into a voltage meter which will register approximately 0.5 full scale when the battery voltage is in the neighborhood of its rated voltage output. The switches 37 and 38 permit the operator to'determine in which of the two target circuits an open or short has occurred. Thus, if the leads to target for instance are open, the meter will read greater than 0.5 full scale and opening switch 38 will have no efiect upon the meter reading. On the other hand, suppose that the leads to target it), for instance, are shorted, in which case the meter will read less than 0.5 full scale. Opening of switch 38 will then cause deflection of the meter to greater than 0.5 full scale. 1

I have found in practice that a battery of approximately 90 volts output and a voltage divider network so pro' portioned as to give a potential difference of approximately 21 volts across the target electrodes gives excellent results. However, it will be obvious that other values may serve equally as well without impairing the operation of the target indicator system.

From the foregoing, it can be seen that if cables 31 and 32 are simply the standard twisted pair wound on drums, as is both convenient and customary, the attenuation of high frequencycurrents will be exceedingly large. Furthermore, this attenuation will be increased as the lengths of the cable are increased. By use of low frequency currents as explained heretofore, my indicator has functioned perfectly using twisted pair cables up to a distance of A of a mile, and shorter distances Wherein the excess length of cable was wound on the drums. ,It is readily apparent that a great saving in expense is made with my system in the use of standard cable alone instead of expensive high frequency-cable, not to mention the convenience and efficiency to be gained by using drums or reels to carry the excess cable.

While I have shown and described my invention as used in a dueling course of fire system, it having particular utility in such an arrangement, it is obvious that an indicating system for signaling hits on a single target may be had byutilizing only one target and the indicator circuit components associated therewith.

What I claim is:

1. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source for charging the plates of each of said targets to establish a potential dilference therebetween, said plates being adapted to be discharged by passage of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, and means linking the indicator circuit of each target with the indicator circuits of the other targets for signaling to the circuits of the other targets when the respective target has been struck first.

2. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source for charging the plates of each of said targets to establish a potential difierence therebetween, said plates being adapted to be discharged by passage of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, and means responsive to the charging current of the target which has been struck first to lock out the indicator circuits associated with the targets which have not been struck first.

3. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source for charging the plates of each of said targets to establish a potential diflference therebetween, said plates being adapted to be discharged by passage of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, and means also responsive to the charging current of the target which has been struck first for locking out the indicator circuits associated with the targets which have not been struck first. I 4. In a target shooting apparatus, a plurality of target each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets toa power supply source for charging the plates of each of said targets to establish a potential difierence therebetween, said plates being adapted to be discharged by passage of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, and switch means responsive to the charging current of the target which has been struck first for locking out the indicator circuits associated with the targets which have not been struck first.

5. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source for charging the plates of each of said targets to establish a potential difference therebetween, said plates being adapted to be discharged by passage of a projectile through the target, and an indi cator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck 7 first, eachof said circuits including a relay having normally closed contacts whichare serially connected in each of the other circuits with said power supply source whereby actuation of the relay in one circuit will open said contacts to prevent the other circuits from responding to the charging current of their associated targets.

6. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source for charging the plate of each of said targets to establish a potential difference therebctween, said plates being adapted to be discharged by passageci a projectile through the target, and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, each of said circuits including a relay having normally closed contacts which are serially connected in each of the other circuits with said power supply source whereby actuation of the relay in one circuit will open said contacts to prevent the other circuits from responding to the charging current of their associated targets; and switch means connected in series between the power supply source and each of the other circuits for decnergizing all of the circuits simultaneously for manually resetting the indicator circuits.

7. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source of D. C. voltage, a voltage divider network, a condenser, and a resistor in parallel with the plates of each of said targets for charging the plates of each of said targets to establish a potential difference therebetween, said plates being adapted to be discharged by passage of a projectile through the target; an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, and means linking the indicator circuit of each target with the indicator circuits of the other targets for signaling to the circuits of the other targets when the respective target has been struck first.

8. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source of D. C. voltage, a voltage divider network. a condenser, and a resistor in parallel with the plates of each of said targets for charging the plates of each of said t sts to establish a potential difference therebetwcen, s to; being adapted to be discharged by passage of a p cctile through the target; an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, each of said indicator circuits including a transformer having its primary winding in series between the voltage divider and its associated target, a cold cathode gas-filled tube having a cathode, anode, and control electrode, the secondary of said transformer being in series with said control electrode. and means linking the indicator circuit of each tar-get with the indicator circuits of the other targets for signaling to the circuits of the other targets when the respective target has been struck first.

9. in a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated'from each other: means for connecting each of said targets to a power supply source of D. C. voltage, a voltage'divider network, a condenser, and a resistor in parallel with the plates of each of said targets for charging the plates of each of said targets to establish a potential difference therebetween, said plates being adapted to be discharged tit by passage 'of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, each of said indicator circuits including a transformer having its primary winding in series between the voltage divider and its associated target, a cold cathode gas-filled tube having a cathode, anode, and control electrode, the secondary of said transformer being in series with said control electrode, and a relay coil in series with the anode of said gas-filled tube, the contacts associated with said relay coil being normally closed and connected in series with the anode of each of the gas-filled tubes in the indicator circuits associated with the other targets.

10. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source of D. C. voltage, a voltage divider network, a condenser, and a resistor in parallel with the plates of each of said targets for charging the plates of each of said targets to establish a potential difference therebetween, said plates being adapted to be discharged by passage of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, each of said indicator circuits including a transformer having its primary winding in series between the voltage divider and its associated target, a cold cathode gas-filled tube having a cathode, anode and control electrode, the secondary of said transformer being in series with'said control electrode, and a relay coil in series with the anode of said gas-filled tube, the contacts associated with said relay coil being normally closed and connected in series with the anode of each of the gas-filled tubes in the indicator circuits associated with the other targets, and means associated with each relay coil for regulating the flow of current therethrough.

11. In a target shooting apparatus, a plurality of targets, each of said targets comprising a plurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source of D. C. voltage, a voltage divider network, a condenser, and a resistor in parallel with the plates of each of said targets for charging the plates of each of said targets to establish a potential difference therebetween, said plates being adapted to be discharged by passage of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, each of said indicator circuits including a transformer having its primary winding in series betwecn'the voltage divider and its associated target, a cold cathode gas-filled tube having a cathode, anode and control electrode, the secondary of said transformer bein series with said control electrode, and a relay coil in series with the anode of said gas-filled tube, the contacts associated with said relay coil being normally closed and connected in series with the anode of each of the gasiilled tubes in the indicator circuits associated with the other targets, and means associated with each relay coil for regulating the flow of current therethrough, said means comprising a potentiometer in parallel with said relay coil, the adjusting arms of each of the said potentioineters being mechanically coupled together for simultaneous adjustment.

12. in a target shooting apparatus, a plurality of targets, each of said targets comprising aplurality of electrically conductive plates spaced apart and insulated from each other; means for connecting each of said targets to a power supply source of D. C. voltage, a voltage divider network, a condenser, and a resistor in parallel with the plates of each of said targets for charging the plates of each of said targets to establish a potential difierence therebetween, said plates being adapted to be discharged by passage of a projectile through the target; and an indicator circuit associated with each of said targets and responsive to the charging current of its associated target for indicating when said associated target has been struck first, each of said indicator circuits including a transformer having its primary winding in series between the voltage divider and its associated target, a gas-filled tube having a cathode, anode, and control electrode, the secondary of said transformer being in series with said control electrode, and a relay coil in series with the anode of said gas-filled tube, the contacts associated with said relay coil being normally closed and connected in series with the anode of each of the gas-filled tubes in the indicator circuits associated with the other targets; and means for testing each of said indicator circuits including a milliammeter in series with one arm of the voltage divider, a switch between the mid-point of the arms of the voltage divider, and a switch in series with the primary winding of each of the transformers, whereby open and short circuit conditions and proper operating conditions may be ascertained.

13. In a target shooting apparatus, a target comprising a plurality of electrically conductive plates spaced apart and insulated from each other, said plates being adapted to be discharged by passage of a projectile through the target, charging circuits means for connecting said plates of said target to a power supply of D. C. voltage, said charging circuit means having a sufficiently high impedance to cause the time base of the charging of said plates to be substantially longer than the time base of the discharge of said plates, and an indicating means associated with said charging circuit means in such manner as to be responsive to the charging current.

14. A target shooting apparatus as defined in claim 13, in which the means associating the indicating means with said charging circuit means includes means inductively coupling said charging circuit means to said indicating means.

15. A target shooting apparatus as defined in claim 13, in which said indicating means comprises an electronic device responsive to the charging current.

References Cited in the file of this patent UNITED STATES PATENTS 474,109 Vogel May 3, 1892 2,185,628 Daum Jan. 2, 1940 2,241,135 Jaimet et al. May 6, 1941 2,576,960 McAvoy Dec. 4, 1951

Images