Automatic input voltage sensing and switching

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

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Parametric Study of Damping Characteristics of Magneto-Rheological Damper: Mathematical and Experimental Approach

Pollack Periodica ◽

10.1556/606.2020.15.3.4 ◽

2020 ◽

Vol 15 (3) ◽

pp. 37-48

Author(s):

Zubair Rashid Wani ◽

Manzoor Ahmad Tantray

Keyword(s):

Structural Control ◽

Research Work ◽

Testing Machine ◽

Input Voltage ◽

Damping Coefficient ◽

Control Technique ◽

Damping Force ◽

Active Devices ◽

Active Structural Control ◽

Magneto Rheological

The present research work is a part of a project was a semi-active structural control technique using magneto-rheological damper has to be performed. Magneto-rheological dampers are an innovative class of semi-active devices that mesh well with the demands and constraints of seismic applications; this includes having very low power requirements and adaptability. A small stroke magneto-rheological damper was mathematically simulated and experimentally tested. The damper was subjected to periodic excitations of different amplitudes and frequencies at varying voltage. The damper was mathematically modeled using parametric Modified Bouc-Wen model of magneto-rheological damper in MATLAB/SIMULINK and the parameters of the model were set as per the prototype available. The variation of mechanical properties of magneto-rheological damper like damping coefficient and damping force with a change in amplitude, frequency and voltage were experimentally verified on INSTRON 8800 testing machine. It was observed that damping force produced by the damper depended on the frequency as well, in addition to the input voltage and amplitude of the excitation. While the damping coefficient (c) is independent of the frequency of excitation it varies with the amplitude of excitation and input voltage. The variation of the damping coefficient with amplitude and input voltage is linear and quadratic respectively. More ever the mathematical model simulated in MATLAB was in agreement with the experimental results obtained.

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New Molecular Scaffolds for Fluorescent Voltage Indicators

10.26434/chemrxiv.7338683.v1 ◽

2018 ◽

Author(s):

Steven Boggess ◽

Shivaani Gandhi ◽

Brian Siemons ◽

Nathaniel Huebsch ◽

Kevin Healy ◽

...

Keyword(s):

Membrane Potential ◽

Action Potentials ◽

Induced Pluripotent Stem Cell ◽

Molecular Wire ◽

Voltage Sensing ◽

Design Synthesis ◽

Cardiac Action ◽

Action Potential Waveform ◽

Induced Pluripotent ◽

Voltage Sensing Domain

<div> <p>The ability to non-invasively monitor membrane potential dynamics in excitable cells like neurons and cardiomyocytes promises to revolutionize our understanding of the physiology and pathology of the brain and heart. Here, we report the design, synthesis, and application of a new class of fluorescent voltage indicator that makes use of a fluorene-based molecular wire as a voltage sensing domain to provide fast and sensitive measurements of membrane potential in both mammalian neurons and human-derived cardiomyocytes. We show that the best of the new probes, fluorene VoltageFluor 2 (fVF 2) readily reports on action potentials in mammalian neurons, detects perturbations to cardiac action potential waveform in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes, shows a substantial decrease in phototoxicity compared to existing molecular wire-based indicators, and can monitor cardiac action potentials for extended periods of time. Together, our results demonstrate the generalizability of a molecular wire approach to voltage sensing and highlights the utility of fVF 2 for interrogating membrane potential dynamics.</p> </div>

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Quantum Calculation of Proton and Other Charge Transfer Steps in Voltage Sensing in the Kv1.2 Channel

10.26434/chemrxiv.8251073 ◽

2019 ◽

Author(s):

Alisher M Kariev ◽

Michael Green

Keyword(s):

Charge Transfer ◽

Energy Charge ◽

Quantum Calculation ◽

Quantum Calculations ◽

Gating Current ◽

Transmembrane Segment ◽

Voltage Sensing ◽

Standard Models ◽

Charge Displacement ◽

Voltage Sensing Domain

Quantum calculations on 976 atoms of the voltage sensing domain of the K<sub>v</sub>1.2 channel, with protons in several positions, give energy, charge transfer, and other properties. Motion of the S4 transmembrane segment that accounts for gating current in standard models is shown not to occur; there is H<sup>+ </sup>transfer instead. The potential at which two proton positions cross in energy approximately corresponds to the gating potential for the channel. The charge displacement seems approximately correct for the gating current. Two mutations are accounted for (Y266F, R300cit, cit =citrulline). The primary conclusion is that voltage sensing depends on H<sup>+</sup> transfer, not motion of arginine charges.

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