The circuit of the invention monitors the amplitude, duration, and repetition rate of telephone ringing bursts. When the ringing bursts are of proper magnitude and form, a bistable circuit is maintained in a reset condition. Should the amplitude, and/or repetition rate, and/or duration, of the ringing bursts fall below specified limits, a signal developed by an integrator circuit is insufficient to prevent a pulse generator from switching the flip-flop circuit into an alarm condition.

In monitoring of yarn finish levels by conductivity, the yarn is grounded prior to the measurement, thus eliminating the effect of static electricity.

A pulmonary monitor for measuring a complex set of variables utilizing a group of three pushbuttons arranged to operate in a hierarchical pattern for facilitating operator control of the functions of the monitor.

A device to digitally meter, monitor and collect liquid, such as urine, from a catheterized patient. As such it is the successor to and improvement upon U.S. Pat. No. 3,769,497. An optional part prevents the migration of bacteria from the monitoring and collecting devices to the patient's body cavity. The device comprises a plurality of uniquely shaped movable containers that empty their contents when filled to a predetermined volume, a catheter for delivering liquid to the containers, movement ...

A proximity monitor for movement at a selected distance from a surface, including a first microwave sensor having an antenna pattern directed toward the surface, the principal component of the pattern parallel to the surface being in the direction of the movement, a second microwave sensor having a second antenna pattern directed toward the surface, the principal component of the second pattern parallel to the surface being at a direction opposite to that of the movement, and the patterns being ...

A noise level monitoring and indicating system includes plural microphones distributed about a classroom, bus, etc. and adapted to drive individual counters to indicate the number of times a minimum sound level has been exceeded by the signal from the associated microphone. Visual indicators are also provided to indicate the instantaneous noise status at selected microphones.

An improved headphone arrangement in which a first audio signal is coupled to a speaker in each headphone and a second audio signal, usually monaural, is coupled to an amplifier and then to the same speaker in each headphone via an isolation network. Switching circuitry are also provided so that the speaker may be connected directly to the second audio source without amplification. The headphone is used as a musician's practice aid or for track-making or similar purposes. The first audio signal ...

Disclosed is a maintenance monitor which at a preselected interval will automatically alert one that the equipment of concern is due for maintenance. The maintenance monitor includes a control unit sensing device such as a switch inductive pickup etc., a programmable module counter activated by a signal from the sensing device and a display for readout of the counter and to advise of the maintenance period or to perform a function.

A pressure equalizing valve for pneumatic tires including a visual display is described which is ideally suited for use with dual tires. A cylindrical housing accommodates a spring biased diaphragm mounted in a first chamber. The diaphragm carries a valve member thereon and acts as a sealing member or element to close two air passageways which are in communication with the dual tires in a conventional dual tire installation. The valve member closes the air passageways when a pre-adjusted and cal...

A paraffin monitor includes a pair of probes which are immersed in a medium having paraffin contained therein. A circuit is connected to the probes which provides an output voltage. The characteristics of the electric circuit changes over a period of time, causing a corresponding change in the voltage output, in accordance with a change in the amount of paraffin on the probes.