Abstract: A respiration and heart rate monitoring apparatus includes a mechanical-electric apparatus for detecting chest movements and electrodes for detecting electric impulses associated with heartbeat. A highly sensitive detector includes a transducer crystal mounted in bridge-like configuration on pair of spaced piers connected by at least one flexible beam member. The transducer crystal and electrodes may be connected to circuitry for producing indications of respiration and heart rate. The circuitry blocks detection of chest motion substantially coincident with the impulses associated with heartbeat to inhibit erroneous indications of respiration caused by chest motion due to heartbeat. The circuitry also may block small, single polarity signals to inhibit erroneous indications of respiration caused by muscle noise.

Abstract: In a module which is usable in a wide band DC to UHF range, a vernier connection is employed in a slip ring and brush assembly. A source is connected to a ring by four slip ring feeds and a load is coupled to the ring by three brush leads. The unequal number of feeds and brushes reduces the standing wave reflections on the ring enabling the module to perform satisfactorily at high frequencies.

Abstract: A circuit deriving an output voltage that is proportional to the logarithm of a DC input voltage susceptible to wide variations in amplitude includes a constant current source which forward biases a diode so that the diode operates in the exponential portion of its voltage versus current characteristic, above its saturation current. The constant current source includes first and second, cascaded feedback, DC operational amplifiers connected in a negative feedback circuit. An input terminal of the first amplifier is responsive to the input voltage. A circuit shunting the first amplifier output terminal includes a resistor in series with the diode. The voltage across the resistor is sensed at the input of the second DC operational feedback amplifier.