Galvanic Decoupling Research Articles

A current source for supporting discharges in pumping lamps of solid-state lasers

A circuit for supporting discharges in pumping lamps of solid-state lasers with the galvanic decoupling is presented. The mathematical model of processes in the circuit is designed. Based on the analysis results of this circuit, the calculation procedure for circuit parameters is given and its volt-ampere characteristic is plotted. The condition for obtaining the maximal switching frequency in the circuit is formulated. The simulation results are experimentally checked.

Spectral control of secondary ion photoeffect: a way to optoionics?

The possibility of optical control over the secondary ion yield from a photoconducting target is demonstrated; using it, one can both increase and decrease this yield. The sign of the secondary ion photoeffect (SIP) is determined by the energy position of each element in the target, which represents a limited solid solution of lead sulfide and cadmium sulfide prepared by thermal deposition in vacuum with subsequent annealing. In addition, the sign of the effect depends on the intensity and spectral composition of illuminating light. The possibility of changing the SIP sign is confirmed by theoretical calculations of the isoenergetic secondary ion spectrum and by the experimental results for lead ions. It is established that the SIP sign is determined by the competition between the compensation and recombination mechanisms. Recombination is accompanied by photoluminescence in both the near- and middle-IR range. The spectral optical control of the secondary ion yield offers new opportunities for creating nanometer-thick materials and makes the galvanic decoupling of the control and technology chains possible, thus paving the way for optoionics.

Photoelectron system in the photon counting mode with a galvanic decoupler for laser sensing of the atmosphere

As an optimal solution of the problem of electromagnetic compatibility in laser sensing of the atmosphere, a photoelectronicic system based on the complete galvanic decoupling of an input circuit sensitive to electromagnetic noise is proposed for the first time. The 32-channel photoelectronicic system operates in the photon counting mode and has a TTL/CMOS compatible output matched to a load on a 50-Ω cable.

A system for measuring the electromagnetic characteristics of the KTM tokamak

A system for measuring electromagnetic characteristics of the KTM tokamak physical setup with the magnetic thermal insulation of plasmas includes primary signal-processing modules, interface converters, and data recording unit. When the input signal varies from −300 to +300 V in a 0-to 500-kHz frequency band, the reduced error of channels measuring signals from sensors is 1.5%. The system uses a channel-by-channel galvanic decoupling for protecting the equipment. The throughput of the digital data transmission channels is 100 Mbit/s per channel. The system is intended for operation with 160 measuring channels.

A Controller for Heating a Liquid-Metal Ion Source

A pulse controller for heating a liquid-metal ion emitter in which a standard platinum resistance thermometer (R0 = 100 Ω) simultaneously acts as a heater and temperature sensor has been developed. High-voltage galvanic decoupling between the controller and power supply circuits makes it possible to keep the ion emitter and controller potential at a level of 6–12 kV with respect to the ground. The ion emitter is heated by constant-amplitude current pulses with an adjustable duration. The voltage across the heater is proportional to its resistance and, hence, temperature. The controller stabilizes the temperature of the ion emitter in the range 130–220°C with an accuracy of better than ±1°C. The efficiency of the device is 30%.

Differential optocoupler amplifier with low noise, low power and balanced output

An optocoupler with differential input and balanced output was realized to make galvanic decoupling of a particle detector located in a high common mode disturbance environment. The circuit configuration incorporates a true differential optocoupled feedback, with low bias current in LEDs and photodiodes. The present circuit improves by a factor two the dynamic range of a previous solution. Large Common Mode (CMRR) and Power Supply (PSRR) Rejection Ratio, low crossover distortion, high dynamic range, low noise and power dissipation have been achieved.

A linear, low-noise, low-power optocoupler amplifier for bolometric detectors

We present an optocoupler with differential inputs and balanced output, which was realized to make galvanic decoupling in a bolometric detector read-out chain. The circuit configuration incorporates a true differential optocoupled feedback, with low bias current in LEDs and photodiodes. Large Common Mode (CMRR) and Power Supply (PSRR) Rejection Ratio, low crossover distortion, high dynamic range, low noise and power dissipation have been achieved.

Galvanic decoupling of a postcolumn amperometric detector in capillary electrophoresis

A postcolumn amperometric detector for capillary electrophoresis techniques with galvanic decoupling of the detection electrodes and the detection circuit from the power unit of the detector (via a laboratory constructed d.c.-d.c. converter) and from the recording devices (via an opto-coupling device) was developed. The high insulating resistance achieved in this way (ca. 10 11−10 12 Ω ) reduced leak currents from the electrophoretic equipment through the detector to the low pA level. It was also effective in eliminating problems due to changes in the potential at the column outlet as found when current detection devices were used. The decoupling protected the detector in situations when the column outlet was at a potential of 4–5 kV. The detector was tested by isotachophoretic experiments carried out in a hydrodynamically closed separation compartment. Dispersions of the analyte zones in the detector were reduced about tenfold in comparison with a previous design of the detector. Experiments with a urine sample, however, revealed that the resolving power of the detector is limited in the isotachophoretic separations of complex mixtures of electrochemically active constituents. The use of a copper electrode was tested in the separation of triethylenetetramine and impurities present in its technical-grade preparation. This detection approach was shown to provide a high sensitivity for this amine and for impurities forming strong complexes with Cu(II) cations.

Method of measuring direct and alternating currents with galvanic decoupling

A method is described for measuring direct and alternating microcurrents with galvanic decoupling. The method is based on the dependence of the current drawn by an operational amplifier circuit on the current measured. The measuring circuit is galvanically decoupled by a transformer which also supplies the power for the electronics. The error of measurement is less than 0.4% for direct current and 0.8% for alternating currents in the frequency band 20 Hz to 10 kHz.

MEMPHIS 2000-a modular experiment multiparameter pulse height instrumentation system

For the data acquisition in nuclear physics experiments with multidetector arrays like OSIRIS, the MEMPHIS 2000 system has been developed. The important features are the compact mechanics, the galvanic decoupling of the sensitive analog part from the host computer power supplies, and simple interfacing with existing computer hardware and ADCs. The use of bit-slice processors provides software control of the setup and the configuration of the whole system. The one-crate version consists of 28 high-resolution (16-b) input channels for NIM-ADCs (Silena Type 7420/G, 7411), two bit-slice processors for ADC control, and three microprocessors for software download, data transfer, and setup. Online acquisition, recording, and analysis of experimental data as well as experiment control are implemented on the VAX-Station.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Magnetpwiderstandsdetektoren für bubblespeicher

The principles of magnetoresistive permalloy detectors for bubble sensing and methods for increasing the bubble signal are briefly discussed. To completely utilize the magnetoresistive properties of the detector material, galvanic decoupling of the domain stretcher from the sensor strip must be provided. The characteristics of thin-film chevron stretcher detectors are presented which are galvanically decoupled from the stretcher bars by an insulating layer. For the chevron stretcher detectors usually employed, the domain signal is created when the sensor magnetization lies nearly parallel to the input current. Due to the cos 2 θ dependence of the magnetoresistance, the optimum signal sensitivity will be obtained near the 45° orientations. This condition can be fulfilled by positioning the sensor strip asymmetrically with respect to successive chevron columns of the domain stretcher. By this arrangement, the signal sensitivity is improved by about 50% compared to the sensor symmetrically positioned. Furthermore, in a strobe window which is about 20% of the read cycle and coincides with the signal peak, considerable improvement of the ONE/ZERO ratio is obtained. Operating the asymmetrical sensor in a 4 kbit bubble memory chip at 100 kHz drive field frequency, a signal sensitivity of 2 mV/mA was obtained. In a 2 μs wide strobe window, the ONE/ZERO ratio was ⩾20 dB. Finally, the properties of a thick-film serpentine-type detector are discussed in comparison with thin-film sensors.