Two circuit solid state limit switch (1no and 1nc)

Claim 2

A firing circuit for providing a switch with the equivalent of a one normally open (1NO) and one normally closed (1NC) contact arrangement comprising: a. a pair of input terminals for connection to a voltage source; b. a trigger circuit connected in circuit with said input terminals to be supplied with operating voltage, said trigger circuit including first and second solid state electronic devices each having two main electrodes and a control electrode for controlling conduction between said main electrodes; c. said first solid state electronic device having a conducting condition and a non-conducting condition, and said second solid state electronic device having a conducting condition and a non-conducting condition; d. circuit means interconnecting certain of said electrodes of said first and second solid state electronic devices such that when said first solid state electronic device is in said conducting condition said second solid state electronic device is in said non-conducting condition and when said first solid state electronic device is in said non-conducting condition said second solid state electronic device is in said conducting condition; e. first and second oscillators each connected in circuit with a separate one of said first and second solid state electronic devices for operation in response to voltages appearing at corresponding ones of said main electrodes to produce oscillation outputs only when the associated device is in said non-conducting condition, whereby said oscillators have opposite output conditions at any given time; f. first and second transformers each having a primary winding and a secondary winding, each of said primary windings being connected in circuit with a separate one of said oscillators for energization in accord with the output of the associated oscillator whereby said secondary windings have opposite output conditions at any given time; g. said secondary winding of said first transformer being connected to a first load and said secondary winding of said second transformer being connected to a second load, said secondary winding outputs being electrically isolated from said voltage source and from each other thereby also electrically isolating said first load and said second load from said voltage source and from each other; and h. an actuating switch connected in circuit with the control electrode of said first solid state electronic device, said actuating switch being actuatable between an open condition wherein a first voltage is established at said associated control electrode of said first solid state electronic device, said first voltage condition established when said actuating switch is in said open condition comprising a small voltage causing said first solid state electronic device to assume said non-conducting condition and said second solid state electronic device to assume said conducting condition, and a closed condition wherein a second different voltage condition is established at said associated control electrode of said first solid state electronic device, said second voltage condition established when said actuating switch is in said closed condition comprising a larger voltage causing said first solid state electronic device to assume said conducting condition and said second solid state electronic device to assume a nonconducting condition.

Claim 3

A circuit as defined in claim 1 wherein said first and second devices comprise NPN-transistors each having emitter, collector and base electrodes, the emitter electrodes of said devices being connected together and the collector electrode of said first device being connected to the base electrode of said second device.

Claim 4

A circuit as defined in claim 1 wherein the frequency of the oscillation outputs of said oscillators is approximately within the range of from 1 to 3 KHZ.

Claim 5

A circuit as defined in claim 1 wherein each of said oscillators comprises a unijunction transistor having an emitter electrode and a pair of base electrodes, and a series connection of a resistor and a capacitor connected for energization in accord with voltage of one of the main electrodes of the associated device, the emitter electrode of each unijunction transistor being connected to a point between the associated resistor and capacitor whereby voltage of each capacitor is applied to the emitter of the associated unijunction transistor.

Claim 6

A circuit as defined in claim 1 further including a pair of Triacs each having a gate and two main terminals, each of said secondary windings being connected between the gate and one of the main terminals of a separate one of said Triacs.

Claim 7

A limit switch comprising: a. a housing defining a cavity; b. a switch within said cavity actuatable between open and closed conditions; c. actuating means mounted on the exterior of said housing for effecting actuation of said switch; and d. a firing circuit within said cavity controlled by said switch for providing the equivalent of a one normally open (1NO) and one normally closed (1NC) contact arrangement, said firing circuit comprising: I. a pair of input terminals for connection to a voltage source; II. a trigger circuit connected in circuit with said input terminals to be supplied with operating voltage, said trigger circuit including first and second solid state electronic devices each having two main electrodes and a control electrode for controlling conduction between said main electrodes; III. said first solid state electronic device having a conducting condition and a non-conducting condition, and said second solid state electronic device having a conducting condition and a non-conducting condition; IV. first circuit means interconnecting certain of said electrodes of said first and second solid state electronic devices such that when said first solid state electronic device is in said conducting condition said second solid state electronic device is in said non-conducting condition and when said first solid state electronic device is in said non-conducting condition said second solid state electronic device is in said conducting condition; V. first and second oscillators each connected in circuit with a separate one of said first and second solid state electronic devices for operation in response to voltages appearing at corresponding ones of said main electrodes to produce oscillation outputs only when the associated device is in said non-conducting condition, whereby said oscillators have opposite output conditions aT any given time; VI. first and second transformers each having a primary winding and a secondary winding, each of said primary windings being connected in circuit with a separate one of said oscillators for energization in accord with the output of the associated oscillator whereby said secondary windings have opposite output conditions at any given time; VII. said secondary winding of said first transformer being connected to a first load and said secondary winding of said second transformer being connected to a second load, said secondary winding outputs being electrically isolated from said voltage source and from each other thereby also electrically isolating said first load and said second load from said voltage source and from each other; and VIII. second circuit means including said switch for controlling application of voltage to the control electrode of said first solid state electronic device, said switch being actuatable between said open condition wherein a first voltage is established at said associated control electrode of said first solid state electronic device, said first voltage condition established when said switch is in said open condition comprising a small voltage causing said first solid state electronic device to assume said non-conducting condition and said second solid state electronic device to assume said conducting condition, and said closed condition wherein a second different voltage condition is established at said associated control electrode of said first solid state electronic device, said second voltage condition established when said switch is in said closed condition comprising a larger voltage causing said first solid state electronic device to assume said conducting condition and said second solid state electronic device to assume a non-conducting condition.

Claim 8

A limit switch comprising: a. a housing defining a cavity; b. a switch within said cavity actuatable between open and closed conditions; c. actuating means mounted on the exterior of said housing for effecting actuation of said switch; and d. a firing circuit within said cavity controlled by said switch for providing the equivalent of a one normally open (1NO) and one normally closed (1NC) contact arrangement, said firing circuit comprising: I. a pair of input terminals for connection to a voltage source; II. a trigger circuit connected in circuit with said input terminals to be supplied with operating voltage, said trigger circuit including first and second solid state electronic devices each having two main electrodes and a control electrode for controlling conduction between said main electrodes; III. said first solid state electronic device having a conducting condition and a non-conducting condition, and said second solid state electronic device having a conducting condition and a non-conducting condition; IV. first circuit means interconnecting certain of said electrodes of said first and second solid state electronic devices such that when said first solid state electronic device is in said conducting condition said second solid state electronic device is in said non-conducting condition and when said first solid state electronic device is in said non-conducting condition said second solid state electronic device is in said conducting condition; V. first and second oscillators each connected in circuit with a separate one of said first and second solid state electronic devices for operation in response to voltages appearing at corresponding ones of said main electrodes to produce oscillation outputs only when the associated device is in said non-conducting condition, whereby said oscillators have opposite output conditions aT any given time; VI. first and second transformers each having a primary winding and a secondary winding, each of said primary windings being connected in circuit with a separate one of said oscillators for energization in accord with the output of the associated oscillator whereby said secondary windings have opposite output conditions at any given time; VII. said secondary winding of said first transformer being connected to a first load and said secondary winding of said second transformer being connected to a second load, said secondary winding outputs being electrically isolated from said voltage source and from each other thereby also electrically isolating said first load and said second load from said voltage source and from each other; and VIII. second circuit means including said switch for controlling application of voltage to the control electrode of said first solid state electronic device, said switch being actuatable between said open condition wherein a first voltage is established at said associated control electrode of said first solid state electronic device, said first voltage condition established when said switch is in said open condition comprising a small voltage causing said first solid state electronic device to assume said non-conducting condition and said second solid state electronic device to assume said conducting condition, and said closed condition wherein a second different voltage condition is established at said associated control electrode of said first solid state electronic device, said second voltage condition established when said switch is in said closed condition comprising a larger voltage causing said first solid state electronic device to assume said conducting condition and said second solid state electronic device to assume a non-conducting condition.

Claim 9

A limit switch as defined in claim 6 wherein said first and second devices comprise NPN-transistors each having emitter, collector and base electrodes, the emitter electrodes of said devices being connected together and the collector electrode of said first device being connected to the base electrode of said second device.

Claim 10

A limit switch as defined in claim 6 wherein the frequency of the oscillation outputs of said oscillators is approximately within the range of from 1 to 3 KHZ.

Claim 11

A limit switch as defined in claim 6 wherein each of said oscillators comprises a unijunction transistor having an emitter electrode and a pair of base electrodes, and a series connection of a resistor and a capacitor connected for energization in accord with voltage of one of the main electrodes of the associated device, the emitter electrode of each unijunction transistor being connected to a point between the associated resistor and capacitor whereby voltage of each capacitor is applied to the emitter of the associated unijunction transistor.

Claim 12

A limit switch as defined in claim 6 further including a pair of Triacs each having a gate and two main terminals, each of said secondary windings being connected between the gate and one of the main terminals of a separate one of said Triacs.

Claim 13

A firing circuit for providing a switch with the equivalent of a one normally open (1NO) and one normally closed (1NC) contact arrangement comprising: a. a pair of input terminals for connection to a voltage source; b. a first solid state electronic device having an emitter, a collector, and a base; c. said first device being connected in circuit with said pair of input terminals to be supplied with operating voltage; d. a second solid state electronic device having an emitter, a collector, and a base; e. said second device being connected in circuit with said pair of input terminals to be supplied with operating voltage; f. said emitter of said first device being connected to said emitter of said second device and said collector of said first device being connected to said base of said second device; g. a first resistor and a first capacitor connected in series with said first resistor connected to said collector of said first device whereby said first capacitor is charged in accord with voltage at the collector of said first device when the latter is non-conducting; h. a second resistor and a second capacitor connected in series with said second resistor connected to said collector of said second device whereby said second capacitor is charged in accord with voltage at the collector of said second device when the latter is non-conducting; i. a third solid state electronic device having an emitter and first and second bases, said third device being rendered conductive between its emitter and first base when a first predetermined voltage is applied to its emitter, said emitter of said third device being connected to a point intermediate said first resistor and first capacitor whereby said first capacitor when charged applies a voltage to the emitter of said third device and discharges through the emitter and said first base of said third device when said first capacitor is charged to said first predetermined voltage; j. a fourth solid state electronic device having an emitter and first and second bases, said fourth device being rendered conductive between its emitter and said first base when a second predetermined voltage is applied to its emitter, said emitter of said fourth device being connected to a point intermediate said second resistor and second capacitor whereby said second capacitor when charged applies a voltage to the emitter of said fourth device and discharges through the emitter and said first base of said fourth device when said second capacitor is charged to said second predetermined voltage; k. a first pulse transformer having a primary winding and a secondary winding, said primary winding of said first pulse transformer being connected to said first base of said third device for energization in response to discharge of said first capacitor, and said secondary winding of said first pulse transformer when energized providing said firing circuit with a first electrically isolated output; l. a second pulse transformer having a primary winding and a secondary winding, said primary winding of said second pulse transformer being connected to said first base of said fourth device for energization in response to discharge of said second capacitor, and said secondary winding of said second pulse transformer when energized providing said firing circuit with a second electrically isolated output; m. an actuating switch connected in circuit between said pair of input terminals and said first device to control application of voltage to the base of said first device; and n. said actuating switch being actuatable between an open contact condition and a closed contact condition, said actuating switch when in said open contact condition establishing a first voltage condition at the base of said first device to render one of said first and second devices conducting and the other of said first and second devices non-conducting so that an output is produced at one of said first and second electrically isolated outputs, and said actuating switch when in said closed contact condition establishing a second different voltage condition at the base of said first device to render said one of said first and second devices non-conducting and said other of said first and second device conducting so that an output is produced at the other of said first and second electrically isolated outputs.

Claim 14

A firing circuit for providing a switch with the equivalent of a one normally open (1NO) and one normally closed (1NC) contact arrangement comprising: a. a pair of input terminals for connection to a voltage source; b. a first solid state electronic device having an emitter, a collector, and a base; c. said first device being connected in circuit with said pair of input terminals to be supplied with operating voltage; d. a second solid state electronic device having an emitter, a collector, and a base; e. said second device being connected in circuit with said pair of input terminals to be supplied with operating voltage; f. said emitter of said first device being connected to said emitter of said second device and said collector of said first device being connected to said base of said second device; g. a first resistor and a first capacitor connected in series with said first resistor connected to said collector of said first device whereby said first capacitor is charged in accord with voltage at the collector of said first device when the latter is non-conducting; h. a second resistor and a second capacitor connected in series with said second resistor connected to said collector of said second device whereby said second capacitor is charged in accord with voltage at the collector of said second device when the latter is non-conducting; i. a third solid state electronic device having an emitter and first and second bases, said third device being rendered conductive between its emitter and first base when a first predetermined voltage is applied to its emitter, said emitter of said third device being connected to a point intermediate said first resistor and first capacitor whereby said first capacitor when charged applies a voltage to the emitter of said third device and discharges through the emitter and said first base of said third device when said first capacitor is charged to said first predetermined voltage; j. a fourth solid state electronic device having an emitter and first and second bases, said fourth device being rendered conductive between its emitter and said first base when a second predetermined voltage is applied to its emitter, said emitter of said fourth device being connected to a point intermediate said second resistor and second capacitor whereby said second capacitor when charged applies a voltage to the emitter of said fourth device and discharges through the emitter and said first base of said fourth device when said second capacitor is charged to said second predetermined voltage; k. a first pulse transformer having a primary winding and a secondary winding, said primary winding of said first pulse transformer being connected to said first base of said third device for energization in response to discharge of said first capacitor, and said secondary winding of said first pulse transformer when energized providing said firing circuit with a first electrically isolated output; l. a second pulse transformer having a primary winding and a secondary winding, said primary winding of said second pulse transformer being connected to said first base of said fourth device for energization in response to discharge of said second capacitor, and said secondary winding of said second pulse transformer when energized providing said firing circuit with a second electrically isolated output; m. an actuating switch connected in circuit between said pair of input terminals and said first device to control application of voltage to the base of said first device; and n. said actuating switch being actuatable between an open contact condition and a closed contact condition, said actuating switch when in said open contact condition establishing a first voltage condition at the base of said first device to render one of said first and second devices conducting and the other of said first and second devices non-conducting so that an output is produced at one of said first and second electrically isolated outputs, and said actuating switch when in said closed contact condition establishing a second different voltage condition at the base of said first device to render said one of said first and second devices non-conducting and said other of said first and second device conducting so that an output is produced at the other of said first and second electrically isolated outputs.

Claim 15

A firing circuit as defined in claim 11 wherein: a. said first and second devices each comprises a transistor; and b. said third and fourth device each comprises a unijunction transistor.

Claim 16

A firing circuit as defined in claim 11 further including: a. a fifth solid state electronic device having a gate and first and second main terminals; and b. said secondary winding of said first pulse transformer being connected between said gate and One of said main terminals of said fifth device wherein said first electrically isolated output is produced only when said fifth device is in conducting condition.

Claim 17

A firing circuit as defined in claim 13 further including: a. a third resistor and third capacitor connected in series between said first and second main terminals of said fifth device; and b. said fifth device comprising a Triac.

Claim 18

A firing circuit as defined in claim 14 further including: a. a sixth solid state electronic device having a gate and first and second main terminals; and b. said secondary winding of said pulse transformer being connected between said gate and one of said main terminals of said sixth device wherein said second electrically isolated output is produced only when said sixth device is in conducting condition.

Claim 19

A firing circuit as defined in claim 19 further including: a. a fourth resistor and fourth capacitor connected in series between said first and second main terminals of said sixth device; and b. said sixth device comprising a Triac.

Claim 20

A firing circuit as defined in claim 19 further including: a. a full wave bridge rectifier having a first pair of terminals and a second pair of terminals; b. said first pair of terminals of said rectifier being connected to said pair of input terminals; c. a Zener diode connected to said second pair of terminals of said rectifier; d. said first device being connected in circuit with said pair of input terminals through said Zener diode; and e. said actuating switch comprising a magnetic reed switch.

Claim 21

In a limit switch actuating means mounted in an actuating head and switch actuating means mounted in a housing, said switch actuating means being responsive to operation of said actuating mechanism, the improvement of a firing circuit for providing said limit switch with the equivalent of one normally open (1NO) and one normally closed (1NC) contact arrangement comprising: a. a pair of input terminals for connection to a voltage source; b. a first transistor having an emitter, a collector, and a base; c. said first transistor being connected in circuit with said pair of input terminals to be supplied with operating voltage; d. a second transistor having an emitter, a collector, and a base; e. said second transistor being connected in circuit with said pair of input terminals to be supplied with operating voltage; f. said emitter of said first transistor being connected to said emitter of said second transistor and said collector of said first transistor being connected to said base of said second transistor; g. a first resistor and a first capacitor connected in series with said first resistor connected to said collector of said first device whereby said first capacitor is charged in accord with voltage at the collector of said first transistor when the latter is non-conducting; h. a second resistor and a second capacitor connected in series with said second resistor connected to said collector of said second transistor whereby said second capacitor is charged in accord with voltage at the collector of said second transistor when the latter is non-conducting; i. a first unijunction transistor having an emitter and first and second bases, said first unijunction transistor being rendered conductive between its emitter and first base when a first predetermined voltage is applied to its emitter, said emitter of said first unijunction transistor being connected to a point intermediate said first resistor and first capacitor whereby said first capacitor when charged applies a voltage to the emitter of said first unijunction transistor and discharges through the emitter end said first base of said first unijunction transistor when said first capacitor is charged to said first predetermined voltage; j. a second unijunction transistor having an emitter and first and second bases, said second unijunction transistor bEing rendered conductive between its emitter and said first base when a second predetermined voltage is applied to its emitter, said emitter of said second unijunction transistor being connected to a point intermediate said second resistor and second capacitor whereby said second capacitor when charged applies a voltage to the emitter of said second unijunction transistor and discharges through the emitter and said first base of said second unijunction transistor when said second capacitor is charged to said second predetermined voltage; k. a first pulse transformer having a primary winding and a secondary winding, said primary winding of said first pulse transformer being connected to said first base of said first unijunction transistor for energization in response to discharge of said first capacitor, and said secondary winding of said first pulse transformer when energized providing said firing circuit with a first electrically isolated output; l. a second pulse transformer having a primary winding and a secondary winding, said primary winding of said second pulse transformer being connected to said first base of said second unijunction transistor for energization in response to discharge of said second capacitor, and said secondary winding of said second pulse transformer when energized providing said firing circuit with a second electrically isolated output; m. an actuating switch connected in circuit between said pair of input terminals and said first transistor to control application of voltage to the base of said first transistor; and n. said actuating switch being actuatable by said switch actuating means mounted in said housing between an open contact condition and a closed contact condition, said actuating switch when in said open contact condition establishing a first voltage condition at the base of said first transistor to render one of said first and second transistors conducting and the other of said first and second transistors non-conducting so that an output is produced at one of said first and second electrically isolated outputs, and said actuating switch when in said closed contact condition establishing a second different voltage condition at the base of said first transistor to render said one of said first and second transistors non-conducting and said other of said first and second transistors conducting so that an output is produced at the other of said first and second electrically isolated outputs.

Claim 22

In a limit switch actuating means mounted in an actuating head and switch actuating means mounted in a housing, said switch actuating means being responsive to operation of said actuating mechanism, the improvement of a firing circuit for providing said limit switch with the equivalent of one normally open (1NO) and one normally closed (1NC) contact arrangement comprising: a. a pair of input terminals for connection to a voltage source; b. a first transistor having an emitter, a collector, and a base; c. said first transistor being connected in circuit with said pair of input terminals to be supplied with operating voltage; d. a second transistor having an emitter, a collector, and a base; e. said second transistor being connected in circuit with said pair of input terminals to be supplied with operating voltage; f. said emitter of said first transistor being connected to said emitter of said second transistor and said collector of said first transistor being connected to said base of said second transistor; g. a first resistor and a first capacitor connected in series with said first resistor connected to said collector of said first device whereby said first capacitor is charged in accord with voltage at the collector of said first transistor when the latter is non-conducting; h. a second resistor and a second capacitor connected in series with said second resistor connected to said collector of said second transistor whereby said second capacitor is charged in accord with voltage at the collector of said second transistor when the latter is non-conducting; i. a first unijunction transistor having an emitter and first and second bases, said first unijunction transistor being rendered conductive between its emitter and first base when a first predetermined voltage is applied to its emitter, said emitter of said first unijunction transistor being connected to a point intermediate said first resistor and first capacitor whereby said first capacitor when charged applies a voltage to the emitter of said first unijunction transistor and discharges through the emitter end said first base of said first unijunction transistor when said first capacitor is charged to said first predetermined voltage; j. a second unijunction transistor having an emitter and first and second bases, said second unijunction transistor bEing rendered conductive between its emitter and said first base when a second predetermined voltage is applied to its emitter, said emitter of said second unijunction transistor being connected to a point intermediate said second resistor and second capacitor whereby said second capacitor when charged applies a voltage to the emitter of said second unijunction transistor and discharges through the emitter and said first base of said second unijunction transistor when said second capacitor is charged to said second predetermined voltage; k. a first pulse transformer having a primary winding and a secondary winding, said primary winding of said first pulse transformer being connected to said first base of said first unijunction transistor for energization in response to discharge of said first capacitor, and said secondary winding of said first pulse transformer when energized providing said firing circuit with a first electrically isolated output; l. a second pulse transformer having a primary winding and a secondary winding, said primary winding of said second pulse transformer being connected to said first base of said second unijunction transistor for energization in response to discharge of said second capacitor, and said secondary winding of said second pulse transformer when energized providing said firing circuit with a second electrically isolated output; m. an actuating switch connected in circuit between said pair of input terminals and said first transistor to control application of voltage to the base of said first transistor; and n. said actuating switch being actuatable by said switch actuating means mounted in said housing between an open contact condition and a closed contact condition, said actuating switch when in said open contact condition establishing a first voltage condition at the base of said first transistor to render one of said first and second transistors conducting and the other of said first and second transistors non-conducting so that an output is produced at one of said first and second electrically isolated outputs, and said actuating switch when in said closed contact condition establishing a second different voltage condition at the base of said first transistor to render said one of said first and second transistors non-conducting and said other of said first and second transistors conducting so that an output is produced at the other of said first and second electrically isolated outputs.

Claim 23

In a limit switch as defined in claim 18 further including: a. a first solid state electronic device having a gate and a pair of main terminals; and b. said secondary winding of said first pulse transformer being connected between said gate and one of said pair of main terminals of said first device wherein said first electrically isolated output is produced only when said first device is in conducting condition.

Claim 24

In a limit switch as defined in claim 19 further including: a. a second solid state electronic device having a gate and a pair of main terminals; and b. said secondary winding of said second pulse transformer being connected between said gate and one of said pair of main terminals of said second device wherein said second electrically isolated output is produced only when said second device is in conducting condition.