Simple biofeedback device to reduce excessive vocal intensity.
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Biofeedback, Psychology↗
Biomedical subjects
R McGillivray
Publications and source records attributed to R McGillivray.
Simple ECG lead tester.
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Electric Conductivity↗
Detection of takeoff potential from intracellular recordings.
The measurement of takeoff potential from intracellular recordings of the cardiac action potential may be useful in the study of the cardiac action potential may be useful in the study of spontaneous automaticity and of the effects of cardioactive drugs on active propagation. We describe a circuit capable of detecting and storing the membrane potential at a point where the slope of the membrane potential exceeds a preset value. The capability of this circuit to track the takeoff potential was tested using intracellular recordings from cardiac Purkinje fibers during spontaneous automaticity as well as during electrical stimulation.
Action Potentials↗
Continuous on-line beat-to-beat analysis of AV conduction time.
A simple analog circuit is described which is capable of measuring on a beat-to-beat basis P-R, R-P, P-P, and R-R intervals during sinus rhythm and paroxysmal supraventricular tachycardia. In addition the circuit will emit a pulse when the consecutively alternating P and R wave sequence is interrupted thereby signalling a trigger problem or a change in rhythm. The operation of the device requires proper P and R wave sensing and provides outputs which are linear over a range of rates which are applicable to the human heart.
Atrioventricular Node↗
A circuit for measuring peak potential.
The measurement of maximal potential is an integral part of several biological signal analyzers. We designed a circuit, which, unlike previously described devices that perform this function, is capable of picking a positive peak at below ground potentials or a negative peak above ground. Other features include user-selected decay characteristics, allowing beta-to-beat following and rejection of base-line noise. The circuit was implemented and tested with intracellular signals recorded from cardiac Purkinje fibers.
Action Potentials↗
Circuit for measurement of instantaneous frequency.
This paper describes a circuit that measures the instantaneous frequency of a pulse train applied to the input. Analog outputs are provided that are linearly proportional to the interval between successive pulses and to the reciprocal of that same interval. The design is based upon well-established operational amplifier circuits and can be built with readily available components. The range over which the circuit operated can be changed by the selection of a single resistor, and the initial calibration requires the adjustment of only three components.
Electronics, Medical↗
Dual-path capacitance compensation network for microelectrode recordings.
Commercially available microelectrode preamplifiers have a built-in capacity compensation circuit. When a shielded cable is utilized to transmit the signal from the microelectrode to the preamplifier the compensative ability of this circuit may be inadequate and may result in a less than desired frequency response. We describe a dual-path capacitance compensation circuit that resolves this problem without impairment of the shielding properties.
Electronics, Medical↗