Fluid level indicator

Claim 2

In an indicator for detecting the level of fluid in a container, the combination of a fluid level probe positioned within the container so as to be immersed in the fluid when the fluid is at a predetermined level to be detected, a DC source in circuit with the container, a warning device, relay means operative when energized to cause the warning device to be actuated, an oscillator driven by the DC source and having the relay means in the output thereof, the oscillator including direct-coupled input and output transistors of opposite conductivity types, the input transistor having the base-emitter thereof connected across the DC source and the collector thereof connected to the base of the output transistor, a resistance in series with the DC SOURCE AND THE BASE OF the input TRANSISTOR, THE OUTPUT TRANSISTOR HAVING THE EMITTER-collector thereof connected across the DC source, the emitter thereof connected to the base of the input transistor and the collector thereof connected to the relay means, a timing circuit including a primary timing capacitor and a primary timing resistor in series and interconnecting the collector of the input transistor with the base of the input transistor, the timing circuit being operative to control the duration of the pluses supplied to the relay means. a probe having a series therewith a secondary timing resistor and a secondary timing capacitor, the probe when immersed in the fluid connecting the secondary resistor and secondary capacitor between the lower potential side of the DC source and the timing circuit so that the timing circuit has a certain time-constant and the output pulses have a corresponding duration inadequate to cause the relay means to be energized., the probe when not immersed in the fluid disconnecting the secondary capacitor from between the low potential side of the DC source and the timing circuit so that the timing circuit has another time-constant uninfluenced by the secondary resistor and the secondary capacitor and the output pulses have an increased duration for causing the relay means to be energized and accordingly the warning device to be actuated.

Claim 3

In an indicator for detecting the level of fluid in a container, the combination of a fluid level probe positioned within the container so as to be immersed in the fluid when the fluid is at a predetermined level to be detected, a DC source in circuit with the container, a warning device, relay means operative when energized to cause the warning device to be actuated, an oscillator driven by the DC source, a time delay network interconnecting the relay means and the output of the oscillator and operative to prevent transients from energizing the relay means, the oscillator including direct-coupled input and output transistors of opposite conductivity types, the input transistor having the base-emitter thereof connected across the DC source and the collector thereof connected to the base of the output transistor, a resistance in series with the DC source and the base of the input transistor, the output transistor having the emitter-collector thereof connected across the DC source, the emitter thereof connected to the base of the input transistor and the collector thereof connected to the time delay network, a timing circuit including a primary timing capacitor and a primary timing resistor in series and interconnecting the collector of the output transistor with the base of the input transistor, the timing circuit being operative to control the duration of the pulses supplied To the relay means, a probe having in series therewith a secondary timing resistor and a secondary timing capacitor, the probe when immersed in fluid connecting the secondary resistor and secondary capacitor between the low potential side of the DC source and the timing circuit so that the timing circuit has a certain time-constant and the output pulses have a corresponding duration inadequate to cause the relay means to be energized, the probe when not immersed in the fluid disconnecting the secondary capacitor from between the low potential side of the DC source and the timing circuit so that the timing circuit has source time-constant uninfluenced by the secondary resistor and the secondary capacitor and the output pulses have an increased duration for causing the relay means to be energized and accordingly the warning device to be actuated.

Claim 4

In an indicator for detecting the level of fluid in a container, the combination of a fluid level probe positioned within the container so as to be immersed in the fluid when the fluid is at a predetermined level to be detected, a DC source in circuit with the container, a warning device, relay means operative when energized to cause the warning device to be actuated, an oscillator driven by the DC source, a time delay network interconnecting the relay means and the output of the oscillator and operative to prevent transients from energizing the relay means, the oscillator including direct-coupled input and output transistors of opposite conductivity types, the input transistor having the base-emitter thereof connected across the DC source and the collector thereof connected to the base of the output transistor, a resistance in series with the DC source and the base of the input transistor, the output transistor having the emitter-collector thereof connected across the DC source, the emitter thereof connected to the base of the input transistor and the collector thereof connected to the time delay network, a timing circuit including a primary timing capacitor and a primary timing resistor in series and interconnecting the collector of the output transistor with the base of the input transistor, the timing circuit being operative to control the duration of the pulses supplied To the relay means, a probe having in series therewith a secondary timing resistor and a secondary timing capacitor, the probe when immersed in fluid connecting the secondary resistor and secondary capacitor between the low potential side of the DC source and the timing circuit so that the timing circuit has a certain time-constant and the output pulses have a corresponding duration inadequate to cause the relay means to be energized, the probe when not immersed in the fluid disconnecting the secondary capacitor from between the low potential side of the DC source and the timing circuit so that the timing circuit has source time-constant uninfluenced by the secondary resistor and the secondary capacitor and the output pulses have an increased duration for causing the relay means to be energized and accordingly the warning device to be actuated.

Claim 5

In an indicator for detecting the level of fluid in a container, the combination of the fluid level probe positioned within the container so as to be immersed in the fluid when the fluid is at a predetermined level to be detected, a DC source in circuit with the container, a warning device, relay means operative when energized to connect the warning device to the DC source so as to cause the warning device to be actuated, an oscillator driven by the DC source, a time delay network interconnecting the relay means and the output of the oscillator and operative to prevent transients from energizing the relay means, the oscillator including direct-coupled input and output transistors of opposite conductivity types, the input transistor having the base emitter path thereof connected across the DC source and the collector thereof connected to the base of the output transistor, a resistance in series with the DC source and the base of the input transistor, the output transistor having the emitter-collector thereof connected across the DC source, the emitter thereof connected to the base of the input transistor and the collector thereof connected to the time delay network, a timing circuit including a primary timing capacitor and a primary timing resistor in series and interconnecting the collector of the output transistor with the base of the input transistor, the timing circuit being operative to control the duration of the pulses supplied to the relay means, a probe having in series therewith a secondary timing resistor and a secondary timing capacitor, the probe when immersed in the fluid connecting the secondary resistor and secondary capacitor between the lower potential side of the DC source of the timing circuit so that the timing circuit has a certain time-constant and the output pulses have a corresponding duration inadequate to cause the relay means to be energized, the probe when not immersed in the fluid disconnecting the secondary capacitor source between the lower potential side of the DC source and the timing circuit so that the timing circuit has another time-constant uninfluenced by the secondary resistor and the secondary capacitor and the output pulses have an increased duration for causing the relay means to be energized and accordingly the warning device to be actuated, and switch means connecting the DC SOURCE to the oscillator or as to energize the relay means and check the operability of the warning device.

Claim 6

In an indicator for detecting the level of fluid in a container, the combination of the fluid level probe positioned within the container so as to be immersed in the fluid when the fluid is at a predetermined level to be detected, a DC source in circuit with the container, a warning device, relay means operative when energized to connect the warning device to the DC source so as to cause the warning device to be actuated, an oscillator driven by the DC source, a time delay network interconnecting the relay means and the output of the oscillator and operative to prevent transients from energizing the relay means, the oscillator including direct-coupled input and output transistors of opposite conductivity types, the input transistor having the base emitter path thereof connected across the DC source and the collector thereof connected to the base of the output transistor, a resistance in series with the DC source and the base of the input transistor, the output transistor having the emitter-collector thereof connected across the DC source, the emitter thereof connected to the base of the input transistor and the collector thereof connected to the time delay network, a timing circuit including a primary timing capacitor and a primary timing resistor in series and interconnecting the collector of the output transistor with the base of the input transistor, the timing circuit being operative to control the duration of the pulses supplied to the relay means, a probe having in series therewith a secondary timing resistor and a secondary timing capacitor, the probe when immersed in the fluid connecting the secondary resistor and secondary capacitor between the lower potential side of the DC source of the timing circuit so that the timing circuit has a certain time-constant and the output pulses have a corresponding duration inadequate to cause the relay means to be energized, the probe when not immersed in the fluid disconnecting the secondary capacitor source between the lower potential side of the DC source and the timing circuit so that the timing circuit has another time-constant uninfluenced by the secondary resistor and the secondary capacitor and the output pulses have an increased duration for causing the relay means to be energized and accordingly the warning device to be actuated, and switch means connecting the DC SOURCE to the oscillator or as to energize the relay means and check the operability of the warning device.

Claim 7

In an indicator for detecting the level of fluid in a container, the combination of a fluid level probe positioned with the container so as to be immersed in the fluid when the fluid is at a predetermined level to be detected, a DC source in circuit with the container, a warning device, relay means operative when energized to connect the warning device to the DC source to cause the warning device to be actuated, an oscillator driven by the DC source, a time delay network interconnecting the relay means and the output of the oscillator, and operative to prevent transients from energizing the relay means, the oscillator including direct-coupled input and output transistoRs of opposite conductivity types, the input transistor having the base-emitter thereof connected across the DC source and the collector thereof connected to the base of the output transistor, a resistance in series with the DC source and the base of the input transistor, the output transistor having the emitter-collector thereof connected across the DC source, the emitter thereof connected to the base of the input transistor and the collector thereof connected to the time delay network, a timing circuit including a primary timing capacitor and a primary timing resistor in series and interconnecting the collector of the output transistor with the base of the input transistor, the timing circuit being operative to control the duration of the pulses supplied to the relay means, a probe having in series therewith a secondary timing resistor and a secondary timing capacitor, the probe when immersed in the fluid connecting the secondary resistor and secondary capacitor between the low potential side of the DC source and the timing circuit so that the timing circuit has a certain time-constant and the output pulses have a corresponding duration inadequate to cause the relay means to be energized, the probe when not immersed in the fluid disconnecting the secondary capacitor from between the low potential side of the DC source and the timing circuit so that the timing circuit has another time-constant uninfluenced by the secondary resistor and the secondary capacitor and the output pulses have an increased duration for causing the relay means to be energized and accordingly the warning device to be actuated, switch means connecting the DC source to the secondary timing capacitor when the probe is not immersed in the fluid so that secondary timing capacitor can become operative when the probe is subsequently immersed in the fluid.

Claim 8

In an indicator for detecting the level of fluid in a container, the combination of a fluid level probe positioned with the container so as to be immersed in the fluid when the fluid is at a predetermined level to be detected, a DC source in circuit with the container, a warning device, relay means operative when energized to connect the warning device to the DC source to cause the warning device to be actuated, an oscillator driven by the DC source, a time delay network interconnecting the relay means and the output of the oscillator, and operative to prevent transients from energizing the relay means, the oscillator including direct-coupled input and output transistoRs of opposite conductivity types, the input transistor having the base-emitter thereof connected across the DC source and the collector thereof connected to the base of the output transistor, a resistance in series with the DC source and the base of the input transistor, the output transistor having the emitter-collector thereof connected across the DC source, the emitter thereof connected to the base of the input transistor and the collector thereof connected to the time delay network, a timing circuit including a primary timing capacitor and a primary timing resistor in series and interconnecting the collector of the output transistor with the base of the input transistor, the timing circuit being operative to control the duration of the pulses supplied to the relay means, a probe having in series therewith a secondary timing resistor and a secondary timing capacitor, the probe when immersed in the fluid connecting the secondary resistor and secondary capacitor between the low potential side of the DC source and the timing circuit so that the timing circuit has a certain time-constant and the output pulses have a corresponding duration inadequate to cause the relay means to be energized, the probe when not immersed in the fluid disconnecting the secondary capacitor from between the low potential side of the DC source and the timing circuit so that the timing circuit has another time-constant uninfluenced by the secondary resistor and the secondary capacitor and the output pulses have an increased duration for causing the relay means to be energized and accordingly the warning device to be actuated, switch means connecting the DC source to the secondary timing capacitor when the probe is not immersed in the fluid so that secondary timing capacitor can become operative when the probe is subsequently immersed in the fluid.