Abstract: A signalling device for weight lifters performing exercises involving bending of the knees. The signalling device is provided with mercury switch for sensing deviation of the axis of the portion of the leg to which the device is attached and a buzzer or other signalling device which signals the lifter when that portion of the leg has deviated from the vertical by a preselected amount. The amount of deviation from the vertical required to activate the signalling device may be varied by an optional angle adjustment. The signalling device allows a weight lifter to exercise properly, but effectively, without risking injury.

Abstract: This safety monitoring system for punch press operators is designed to prevent the operators from being injured by such presses or other factory equipment. Primarily, it consists of a pair of wrist units which are strapped to the wrists of the operators, and which include optical fiber cables and a latching assembly, and the optical fiber cables are used in cooperation with a pair of identical electronic circuits employing LED's, a light sensitive transistor, a pair of other transistors, a zener diode, and a relay, for instantly shutting a punch press on or off.

Abstract: Apparatus for providing switch closure control inputs to a joystick control port of a video console comprising a pair of gloves having separate finger and thumb portions with electrical contacts mounted on the palm surfaces thereof adjacent to the finger and thumb tips. The electrical contacts are connected to selected terminals of a connector adapted for removable insertion into the console control port. Physical contact between the finger and thumb tips obtains electrical connection between associated contacts so as to provide switch closure control inputs to associated terminals of the control port.

Abstract: A warning device particularly for use in a coverall worn by a person in a controlled environment warns if the person has unfastened the garment. The garment has fasteners such as a zipper for opening and closing the garment. A pair of electrical contacts are mounted in the zipper track for contact by the zipper head as the zipper head moves along the zipper track. The zipper head establishes continuity through the contacts as it is drawn past. This provides a signal to a transmitter mounted to the coveralls. The transmitter provides a radio frequency signal to a receiver located in a monitoring area. The receiver provides a warning upon reception of the signal.

Abstract: A personal security alarm characterized by a hand unit transmitter and a torso unit receiver/alarm. The transmitter of the hand unit is actuated by a button positioned at the palm of the user. As the user either voluntarily or involuntarily clutches his or her fist, the actuator button is depressed to energize the transmitter and cause the torso unit to emit a loud, penetrating alarm. The torso unit can only be turned off with a hidden switch.

Abstract: A patient monitor includes an enclosure which is secured to the bed of a patient. The enclosure is electrically connected with a nurse's call panel and the enclosure serves to mount a jack which is electrically connected to the nurse's call panel. This jack includes a normally closed switch which is opened when a mating plug is installed in the jack. The plug is connected by a cord to the gown of the patient in the bed. When the patient attempts to leave the bed the patient's motion pulls the plug from the jack, thereby allowing the switch to close and signalling via the call panel the patient's attempt to leave the bed.

Abstract: An eye shield or eyepiece for a viewing device, especially for a day and night vision sighting device for aiming a weapon essentially comprises a headrest and first and second mounting frames. These components form an assembly for mounting on the housing of a viewing device. For the practical manipulation and adaptation of the headrest to the form of the head of the observer, two hinge-like articulations are provided in mutually spaced relationship on the external face of a forehead rest of the headrest. A relatively low pressure force against the inner face of the forehead rest deforms and correspondingly adapts the elastomeric or flexible plastic headrest.

Abstract: An alarm intended to alert the operator of dangerous equipment, such as the driver of an automobile, when his head tilts as from drowsiness or sleep. Intended to be of utmost convenience so as to encourage its use, the device is gripped between the teeth by a mouthpiece. Vibration concomitant with making the sound it emits is partially transmitted through the bone structure of the head, reducing the needed noise level and so the disturbance of nearby persons. The preferred embodiment is sensitive to tilt in any direction, and may be stored inverted in which position it tolerates large tip angles without sounding.

Abstract: An apparatus and a method for monitoring the activity of a patient comprehend the sensing of the downwardly directed angular inclination of the distal end of the patient's femur to determine when the patient is in an ambulatory enabling position. The electrodes of a mercury switch, which is included in an alarm module that is attached to the patient's thigh, close to produce an electric signal whenever such inclination exceeds a preselected threshold angle. Such signal activates an alarm-generating electrical circuit to produce an alarm with a distinctive sound to provide notice to attending personnel of the possibility of impending injury to the patient.

Abstract: This invention relates to a body height and weight measuring machine, which operates by means of a winding transmission cord means to drive a sliding plate having sensing, measuring, and digital display functions. When the sliding plate moving upwards, the sensing means will receive the refracted infrared rays as a result of a person's height to cause said winding transmission cord means to stop moving; then, a correct height and weight will be displayed thru digital display means. The aforesaid height measurement and its digital display are done by means of a photocell sensing means being coupled to a scale plate that includes a black and transparent strip in alternate arrangement and equal width so as to have said photocell sensing means generating a forward or reverse sequence sensing signal during the sliding plate moving; then, said signals will be shown on a display means driven with driving circuit.

Abstract: The device engages the hand of the operator and maintains same in a fixed position while permitting movement of the fingers. A first rigid part is adapted to be situated adjacent the palm. A second rigid part, aligned with the first part, is adapted to be situated adjacent the back of the hand. The first and second parts are mounted in a fixed, spaced relationship to engage the hand therebetween. The pushbuttons are mounted in sets, each set being aligned with a different finger and adapted to be operated by the pivotal movements of the finger in its plane as the finger is moved relative to the palm.

Abstract: A user operated switch has a support frame mounted to a person's body. A first electrical contact is mounted on and extends from the frame. Contacting structure includes a friction device positioned against a portion of the person's skin and is supported by an electrically conductive support arm. An electrically conducting lever arm has a first end mounted in the friction device in electrical contact with the support arm. A second end of the lever arm is located adjacent the first contact. Skin movement will cause contact between the first contact and the lever arm. The switch may be modified to act as a double throw, single pole switch.

Abstract: A switch holder is made from a rubber or a plastic and has an endless ring-like form or an arcuate form cut at both ends to fit a finger of the worker who makes the welding. A switch having a small depression stroke is mounted on the periphery of the switch holder so as to be pressed by the flank of an adjacent finger. Thus, when the worker gripping a safety holder clamping a welding rod by his hand wearing the switch holder increases the gripping force, or when he intentionally increases the gripping force without holding anything, the push button is pressed by the flank of the adjacent finger. A protective mask body electrically connected to this switch accomodates a conversion means for converting the rotation of the shaft of a motor into a linear movement, and a light-shielding plate connected to the conversion means so as to move between a light shielding position where it covers the window of the mask body and a clearing position where it opens the window.

Abstract: Input unit for electronic equipment, consisting of a body of insulating material with finger guides in which sensor contacts and pushbutton switches are arranged. By moving the finger along the guides characters can be written and the sensor contacts produce corresponding electrical signals. By operating a corresponding pushbutton it is indicated that the writing-in operation is completed.

Abstract: Control apparatus for video games has a control handle spaced apart from and joined to a separate housing by a connecting rod. The housing is contoured and securable to a user's arm, and forms an anchor point for manipulation of the control handle. The user may choose between variable resistive controls and switch controls which operate responsive to movement of the control handle and/or the connecting rod. Multiple individual controls may also be mounted on the handle to control other game functions. Plates having cutouts formed therethrough are attachable to the housing, with the control rod protruding therethrough, the movement of the control rod may thereby be limited by contact with the periphery of the cutout, preventing simultaneous engagement of two or more signal controls.

Abstract: A headset for supporting electrical contact means which are operated by the movement of the jaw and/or the eyebrows is electrically connected to a computer, video game console or the like to provide educational and recreational opportunities to persons who can move only the jaw and eyebrows. A flexible chin strap formed with a chin cup supports a horizontally mounted chin bar having an electrode contact on one end. A housing having a plurality of sides, each inner face of which has mounted thereon an electrode connected to a computer interface is mounted around the chin bar electrode to provide a means for the user to establish contact between the chin bar electrode and one or more of the housing electrodes by up, down or sideward movement of the jaw. An adjustable head band formed to fit above the eyebrows of the user is formed with a contact electrode extending outwardly from the center portion of the headband between the eyes.

Abstract: An adjustable pressure switch is disclosed which has a generally cylindrical plastic case with a cylindrical cavity formed in one side. A mating, cylindrical pressure plate fits within the cavity and is spaced away from the bottom of the cavity by a resilient annular member. A top electrical contact member is mounted to the pressure plate and a bottom electrical contact member is mounted in the case, with the two contact members being normally maintained in spaced relation by the resilient member. A compression ring fitting within a groove in the cavity in the case holds the pressure plate firmly in position. Force applied to the pressure plate urges the same toward the bottom of the cavity until the two contact members make electrical contact. The amount of force required to close the switches can be adjusted by adjusting the position of the top contact member, formed as a set screw threaded into the pressure plate, or by selecting the shape or material of the resilient annular member.

Abstract: A static pick-up may comprise a sapphire substrate of which the upper sure bears at least two metallic electrodes and a dielectric and the lower surface is metallized in a manner to receive directly an electronic circuit adapted to detect the position of a finger placed on the pick-up. The electrodes are coupled to the lower surface metallization by means of metallized passages. The pick-up may be employed as a control means for introducing and correcting data as displayed by a timepiece.

Abstract: A recorder training device comprising a recorder body having a plurality of tone holes provided with a couple of electrodes opposingly disposed around them such that the electrodes may be indicated by electric lights on the corresponding tone hole figures of a recorder pattern shown on an indicator plate, or on the electric lights on the musical scales of a music score pattern indicated on an indicator plate.

Abstract: A self-contained, portable, safety alarm device adapted to be worn on a user's hand for providing an alert signal when, through drowsiness or otherwise, the user's hand relaxes. The device includes at least a partial glove including a fingertip portion adapted to be worn on at least one fingertip of the user, a wristband portion adapted to be worn about the user's wrist, and connecting means connecting the fingertip portion to the wrist portion.The wristband supports a housing which includes a battery, an alarm device energized by the battery, and an on-off switch. The fingertip portion supports a switch electrically connected to the battery and alarm device which provides an open circuit when the user holds the switch against a contact surface, for example, a steering wheel of a vehicle, and provides a closed circuit to permit the battery to energize the alarm device when the user's hand relaxes away from the contact surface.

Abstract: An electronic artificial larynx supported and operated without the use of an operator's hands. The electronic larynx includes a headband which fits securely around the operator's head. A switch is attached to the headband for opening and closing an electrical circuit that includes a signal generator and a tone generator. The switch has a displaceable actuator extending beyond the headband and adherable to the operator's forehead for movement with the forehead relative to the headband. A hollow, non-toxic plastic tube has one end rotatably connected to a stem of the tone generator and another end for placement in the operator's mouth. A linkage assembly connects the tone generator to the headband for permitting universal adjustment of positioning of the tube.

Abstract: A battery powered hearing aid has a remote, momentary shut off switch comprised of two leaf plates mounted in a spaced apart relationship, with each leaf plate having an electrical contact extending inwardly and aligned so that pressure against either leaf plate separates the contacts to open an electrical circuit. When the switch is opened, power from the battery is disconnected from the hearing aid, rendering it non-operational while the leaf plates are under pressure. The remote momentary shut off switch is particularly adapted for mounting in the shoulder area of a hunting vest or the like to permit improved hearing while stalking a quarry without amplifying the firing noise from a shotgun or rifle.

Abstract: A concealable signaling, e.g., radio alarm, device worn on the person and actuated by concealed switch means that include mechanical detents. The engagement of the detents provides secret tactile information back to the wearer. The presently preferred embodiment is a miniature radio alarm transmitter concealed in a device which also serves as a belt buckle. The wearer distends his waist to actuate the transmitter. Tension in the belt moves an element through one or more detent engagements before it activates the transmitter. These detent engagements make transient changes in the belt tension which are felt by the wearer; these inform the wearer of impending activation, so preventing false transmitter signals or alarms.

Abstract: An apparatus for detecting and signalling the presence and absence of movement of an object moving randomly in space and time has a portable transmitter carried by the moving object, such as a human operator. The transmitter transmits a carrier frequency signal so long as the operator continues his random movements. A detector associated with the transmitter detects the random movements and has sensing means which is a sensor that responds to the operator's movements and is movable randomly in three dimensions in response to the movements. The detector has a photo-responsive switch activated by the movement sensor which interrupts the emission of the carrier frequency signal when the human operator is substantially immobile and permits the transmission once the operator renews his movement. A receiver is positioned in an area for receiving the carrier frequency signal.

Abstract: A wand adapted to be held in the hand and provided with a rod-like body provided with a handle having a base at one end and a visual indicator at the opposite end. The base defines a handle for grasping the wand and the base is hollow to house an electronic circuit and a battery for operating the circuit. The circuit is a multivibrator whose output signal oscillates at a given frequency, such as 120 Hz. The visual indicator is coupled with the circuit and is caused to flash at the operating frequency of the circuit when the circuit operates. The base has a pair of spaced terminals thereon which are bridged by the palm of the hand when the base is grasped, and the palm therefore provides a resistance forming part of the circuit to cause the frequency of flashing of the visual indicator to change depending upon the extent to which hand pressure is applied to the base. For increased frequency, greater hand pressure is applied to decrease the resistance accordingly.

Abstract: An improved chin controller system, for controlling a motor-driven wheelchair or the like, comprises an elongated control arm which extends unobtrusively to a location adjacent to occupant's chin and there supports an actuator mechanism, designed with very low profile to present minimum obstruction in front of the user-patient's face. The controller unit is designed so that when not in use, the user may readily move the controller to one side. The actuator carried on the control arm is engageable by the underside of the user's chin and may be moved vertically (depressed) to provide proportional speed control of the wheelchair, and laterally (from side-to-side) in a horizontal plane, to provide proportional left/right steering control. The actuator also comprises means enabling the user to select the desired forward or reverse direction of travel for the wheelchair and also to select between different drive torque levels for the drive motors.

Abstract: A thin-film transparent electrode is provided on the front glass of an electronic wristwatch to form a part of a switching mechanism cooperation with a metal frame provided at the back of the wristwatch. The metal frame is maintained in contact with the operator's wrist in an operative condition. When the operator touches the thin-film transparent electrode, the switching mechanism in its ON condition provides a signal for controlling an operation mode of the electronic wristwatch, for example, a display condition.

Abstract: A personal alarm for runners includes a shoe-mounted sounding mechanism positionable out of the way in running but for actuation by a kick with either foot to depress a switch plunger against the off foot, or actuation by a kick against the ground, an attacker or other object; a key-shut-off provision insures prolongation of the alarm when sounded; an adjustable provision for mounting to a shoe of any size in optimum position and quick detachment/attachment includes a lace-mounted pad with hook-and-loop fabric attachment to the bottom of the case of the sounding mechanism; and the interior of the case displays indentifying indicia for the runner through a transparent dome which waterproofs the case and which shows precisely the location of the switch.

Abstract: A circuit interconnecting a source of electrical energy with a power operated machine. The circuit comprises an interlock device including a motion switch which is adapted to be removably attached to the machine operator's body. The motion switch is movable between a normally deactivated position to prevent the flow of electrical energy from the source to the machine and an activated position to permit the flow of electrical energy from the source to the machine for operating the machine. The motion switch is operable to be moved to the activated position in response to movement of the operator's body.

Abstract: A hemorrhage alarm system having an electrically operated signal device, a source of electrical current, a circuit connecting said current source and signal device, a normally open switch in said circuit and a means swelling on contact with blood and body fluid acting on said switch to close it on contact with blood and body fluid.

Abstract: A belt has a posture warning device maintained therein. The belt includes a strap with a buckle at one end thereof. The strap includes pockets which receive a battery and an electrical bell or buzzer. An electrical contact is maintained on the strap and connected to the battery, while the buzzer is electrically connected to the buckle. Movement of the buckle against the electrical contact completes the circuit between the battery and buzzer to emit a sound indicating to a wearer that he has allowed his abdominal muscles to relax to a point evidencing bad posture. The buckle is biased away from the electrical contact by means of springs interconnected between the strap and buckle such that, when the wearer evidences good posture and abdominal muscle control, the buzzer is inactive.

Abstract: A thumb-sucking alarm system includes a pair of spaced-apart sensor electrodes carried on a moisture-accepting portion of a flexible sensor tape adapted to be wrapped around the user's thumb, the electrodes being respectively connected to conductive lead strips on an elongated coupling portion of the tape, the distal end of which is wrapped around a plug for insertion into a mating receptacle in a housing adapted to be secured by a strap around the user's wrist. The conductive strips contact terminals of a battery-powered transistorized alarm circuit in the housing which generates an audible alarm signal in response to establishment of an electrical path between the electrodes by the moisture in a user's mouth when he sucks his thumb. A test button is provided on the housing for testing the audible signal generating circuit.

Abstract: An alarm safety apparatus for use by operators of motor vehicles, transportation equipment, manufacturing equipment and the like for signaling in response to a specific operator movement or position is provided having a multi-directional movement limit alarm preferably including a soft deformable support which may contain a plurality of electric contact switches, at least one each thereof, oriented along each direction of movement of interest; and wherein the plurality of electric contact switches may be electrically connected to signal and power supply components.

Abstract: A make-break contact assembly useful in the art of musical education comprises switch means and is mounted upon expandible strap means intended to encircle the head of a student to pass adjacent to the chin area and lower jaw and to be responsive to jaw movements to expand or contract the strap means to precipitate the make contact and break contact electrical states of the contact assembly, respectively, selectively indicative of a proper jaw position resulting in proper mouth-playing orientation or an improper jaw position resulting in improper mouth-playing orientation, and visual signalling differentiating between proper and improper jaw positions.

Abstract: A lightweight, somewhat book-shaped control unit having displays, signal lights, data entry keys, and control keys disposed in a panel has one side edge of the case rounded to permit holding in the hand in a fashion that allows pressing of a data entry key with the thumb of the same hand, there being a hand strap to assist in holding with one hand, the strap having its upper end attached to the case parallel to the edge of the case and its lower end attached to the case perpendicular to the edge of the case.

Abstract: Operator controlled devices in the form of hand operated instruments in which a ring worn by an operator is configured to be insertable into a recess in a hand holdable portion of the instrument. The recess includes a fixed contact configuration that is engagable by a non-magnetic bridging contactor on an outer peripheral face of the ring, so that the instrument becomes operational when the contactor is inserted into the recess and engages the fixed contact configuration.

Abstract: A thin-film transparent electrode is provided on the front glass of an electronic wristwatch to form a part of a switching mechanism cooperation with a metal frame provided at the back of the wristwatch. The metal frame is maintained in contact with the operator's wrist in an operative condition. When the operator touches the thin-film transparent electrode, the switching mechanism in its ON condition provides a signal for controlling an operation mode of the electronic wristwatch, for example, a display condition.

Abstract: A new and improved case for electronic wristwatch modules, which case has an improved means for activating the watch display means. The new case of this invention comprises a frame for supporting a module containing a frequency standard, a frequency divider, an electro-optical display means, and switching means for operating the display means; at least one bar retained in an edge of the frame; means for biasing the bar away from the frame; and, means coupling the bar to the switching means, whereby pressure exerted on the bar operates the display means.

Abstract: An electronic circuit having two states, at least one of which is stable and which permits information to pass from one terminal to the other. The circuit can be activated by the flow of a minute electric current through the human body. The circuit is particularly suitable for any hand-held instrument such, for example, as an electronic calculator watch of the digital type and including electronic logic. It permits to activate certain functions or to carry out certain calculations by activating a conductive surface by means of a hand-held metallic pin or the like. This makes it possible to provide a large number of functions or operations and to display numbers say on the face of a watch and to activate each one by touching it with a pin held by the wearer of the watch or instrument.

Abstract: A front glass sheet having a viewing window and conventionally received within a casing of a solid state wristwatch, is made of electrically conductive glass material which manifests conductivity per se, for serving as one of the principal components of a touch sensitive electrode assembly. In one preferred form, the front glass sheet is made of amorphous (glass) semiconductor such as chalcogenide glass of resistivity less than several hundred K.OMEGA. cm.

Abstract: An electronic wristwatch is provided with a touch type contactless switch structure for the purpose of altering the operational mode thereof, which comprises a pair of switch electrodes one being disposed on the viewing window in the engagement relationship with a portion of the operator body and the other being constituted of the enclosure thereof made of electrically conducting material. The one electrode is a film of transparent conductive material and, has an end area leading to the movement accommodated within the interior of the wristwatch. Both of the electrodes are isolated from each other via an electrically non-conducting member of low-melting point glass disposed therebetween which includes an extension overlaying the one electrode at the peripheral portion of the viewing window for allowing for moisture invasion.

Abstract: In at least one embodiment, a sleep inhibiting device comprises a plurality of ring-like, metallic contacting devices worn on adjacent fingers of a human hand. The contacting devices close an electrical circuit when brought into mutual contact as a result of the adjacent fingers being brought into a contiguous relationship. The sleep inhibiting device may also comprise means for physically attracting the ring-like devices to each other, thereby requiring a wearer to consciously apply a countering force to prevent physical contact of the ring-like devices. Upon inadvertent relaxation of the muscles of the hand and fingers of a wearer, the ring-like devices are brought into contact with each other and thereby close a circuit that activates a stimulation means, such as a buzzer, and thereby awakens the wearer. In one embodiment of this invention, the ring-like devices are magnetized and oppositely poled to increase the likelihood of contact upon relaxation of the muscles of the fingers and hand.

Abstract: A chin activated switch for use in adjusting the movement of a binocular microscope along three orthogonal axes allows the operator to utilize his hands and feet to control other devices. This chin switch contains a plurality of microswitches which are activated by specific movements of the chin. A chin plate upon which the operator's chin rests is connected to a pivot rod and rocker assembly the movement of which actuates the microswitches. These microswitches in turn control motors which move the microscope in the desired directions.

Abstract: A switch member for portable, battery operated apparatus, such as staff location systems, which is provided with hearing sets worn on the head, ear-phones, speech amplifiers, radio receivers and the like including at least one attachement or suspension member. The switch member is arranged to be automatically moved to and forcibly retained in a circuit-closing contact position under pressure from the attachment or suspension member of the apparatus.

Abstract: Disclosed is apparatus for keeping a vehicle operator awake by means of an audible alarm or signal responsive to a nodding or tilting forward movement of the head of the operator of the vehicle. The apparatus includes a switch mounted on a hat, ear hook or head band, worn by the vehicle operator and which switch is closed upon the tilting forward of the operator's head to complete an electrical circuit providing power from a battery to an alarm. The battery and alarm may be enclosed in a casing which may be clipped to the operator's wearing apparel, or mounted on the dash board of a vehicle and a flexible electrical line interconnects the hat, head band or ear hook and the casing or dash board to permit freedom of operator movement; also, an electrical connector may be provided on the flexible electrical line to permit the hat, head band or ear hook and casing or dashboard to be electrically and mechanically disconnected.

Abstract: A multi-facetted translucent ball surrounds a lamp which is suspended from an earring clip by a flexible tubular metal shaft which has a wire running there through. The earring clip is U-shaped and has a pair of opposed legs which are spread resiliently apart when the clip is engaged on ear with the lobe between the legs. One leg carries, connected to the wire, a cup for holding a wafer battery. A U-shaped support secured to the clip carries a contact opposite the cup in a position so that the cup is urged toward the contact for engaging opposite terminals of the battery upon spreading of the clip.

Abstract: A head controlled mechanism for the proportional control of a driven devi A mechanism is provided whereby a control signal is generated proportional to the movement of the head of an operator to control the speed and direction of the driven device.

Abstract: The operator of a motor vehicle is provided with a glove or hand-worn member to which one end of a cord or other flexible member is attached with the other end being attached to the operating member of a switch or the trigger of an attention-producing device mounted to a fixed elevated portion of the vehicle located generally above the steering wheel. The cord or other flexible member is of such length that it is not taut when the operator's hand is in a normal driving position on the steering wheel but becomes taut before the operator's hand drops to his or her thigh. The alarm-producing device may be the horn with which the vehicle is normally equipped and the switch for the horn may be electrically interconnected to the storage battery with which the vehicle is normally equipped.

Abstract: A touch actuated electronic switch is disclosed including a surface, accessible to the touch of a human, interconnected with a differential amplifier. In the preferred embodiment, if increased noise immunity or noise protection is desired, a twisted pair of wires is used and interconnected at one end with one wire electrically connected to the touch surface and the other substantially equal length wire being unconnected. Both wires, at the other end, are connected to the input to the differential amplifier. A common mode alternating voltage signal is then provided to the differential amplifier and a substantial alternating frequency output signal shunt is applied to the differential amplifier, in the preferred embodiment, across terminals conventionally used for D.C. offset null purposes. The output of the differential amplifier is then interconnected to an integrator, in the preferred embodiment a capacitor, and the integrator is in turn connected to an additional amplifier.

Abstract: A relay switch for controlling an electronic circuit adapted to adopt two states includes first and second conducting parts spaced apart from one another by an insulating material in a configuration whereby the first and second parts can be connected by a resistance formed by the skin of a user's finger, such connection being effective to control the state of the circuit.