Stabilized power supplies

To get the best productivity out of a Q-ICP-MS instrument, this should have a stabilized power supply and be coupled to a flow injection (FI) system. The stabilized power supply ensures that the instrument is stable and protects the turbo-molecular vacuum pumps from power surges. The FI system allows samples to be diluted on-line, internal standards to be added, and AsH3 to be generated, this improving accuracy, precision, and laboratory productivity [41]. 

If a stabilized power supply with large output voltage Us (e.g. > 100 V) is available, the simple circuit of Fig. (c) can be used, where the current is given by I = Us ce". If [7ceii Us then I = Us/R. This concept was common before 1960. 

Epifluorescence microscope with a 75W Xenon arc lamp fitted to a highly stabilized power supply (see Notes 2 and 3). 

The equipment consists of two electrode compartments (Fig. 2 a,i) which are directly connected with the current stabilized, power supply, an injection block (Fig. 2 d) and a narrow bore tube. To prevent a hydrodynamic flow between the two electrode compartments, a semi-permeable membrane (Pig. 2 h) is mounted. The separation compartment is a narrow bore tube of Teflon (PTPE) with an inside diameter of 0.2 mm and an outside di2uneter of... 

Figure 2. Schematic diagram of an ITP-apparatus. a = PT-electrode b = terminating electrolyte c = drain d = silicone septum e = UV-detector f = conductivity (potential gradient) detector g = silicone septum h = semi-permeable membrane (e.g. cellulose acetate) i = Pt-electrode. p and q lead to a current-stabilized power supply (20 kV). The separation compartment is a PTFE-capi1lary (I.D. =...

Sources are often surrounded by a thermally insulated enclosure to reduce noise caused by refractive index gradients between the hot air near the source and cooler air in the fight path. Short-term fluctuations in spectral output are usually due to voltage fluctuations and can be overcome by use of a stabilized power supply. Long-term changes occur as result of changes in the source material due to oxidation or other high temperature reactions. These... 

The resistance ratio for Chromel-P thermocouple wire was determined with the circuit shown in Fig. 1. A fixed current was supplied to the specimen with a stabilized power supply (Trygon Model H20-1.5) having remote sensing. Two laboratory-type rheostats were used to give additional fine current adjustments the specimen current was maintained at a selected value of 0.10000 amp by adjusting the potential across the standard 1-ohm resistor, Rs, to 0.10000 v. The potential across the standard resistor and the specimen coil was determined with a potentiometer (L N K-3), a null detector (L N Model 9834-1), and an Eppley standard cell. 

For the investigation into the Influence of u.v. radiation on the dielectric properties of polycarbonate, pressed sheets of the material were irradiated at room temperature in air by a standard Hanovia mercury lamp. The lamp provided a spectrum of wavelengths within the range 254 to 546 nm and sample intensities of 2.47 mW cm and 0.91 mW cm respectively at the principal wavelengths of 365 nm and 254 nm. A voltage-stabilized power supply assisted consistency of spectral output. 

As an example, the construction of a stabilized power supply very useful for the development of various devices used in flow techniques, e.g. as source of a Hamamatsu photomultiplier used in chemiluminescence detectors, is presented. Figure 4.20 shows a schematic depiction of the cited electronic circuit, able to supply - -5, -t-12 and —12 V. 

The Spectronic 20 employs a tungsten filament light source, which is operated by a stabilized power supply that provides radiation of constant intensity. After diffraction by a simple reflection grating, the radiation passes through the sample or reference cuvettes to a solid state detector. The Spectronic 20 reads out in transmittance or in absorbance on an LED display or. in the analog model, in transmittance on a meter. 

The Photo Processing System (Platform No. 4) consists of (1) a large surface high power monochromic UV lamp (wavelength = 365 nm and power = 100 mW/cm ) with a mechanical shutter activated by an electrical pulse and an AC stabilized power supply, (2) a cell support and (3) probes and controllers for control and data acquisition during the drop experiment. 

There are cases when there is no need to use expensive potentiostats, and anodic protection can be realized by the use of other dc current sources, for example, stabilized power supplies. These current sources can only be used when the metal is characterized by a wide passive state range, e.g., 0.8 V, and the current needed for maintaining this state varies insignificantly with time. This is connected with the stable conditions of working of the structure, for example, a tank of 18/8 type steel storing H2SO4 (practically constant acid level, thermal, hydrodynamic conditions, etc.). More information on potentiostats can be found in the works of Rickert (1987) and Zhuo and Lin (1992). 

Photoactivity of the films were eompared by Becquerel effect value, measuring Upjj relatively a saturated Ag/AgCl electrode in aerated 1.0 N KCl electrolyte, changing the pH from 1 to 14 by titration with 1.0 N KOH or HCl solution. Pigmented electrodes were illuminated with an arc xenon lamp DKSSh-120 with a stabilized power supply, the light output in the plane of the electrode was 100 mW/cm . For measurement of the quantum yield on a current T pigment films with thickness d from 2 to 300 nm were applied on polished quartz substrates coated with a conductive layer of platinum. The T value was determined from a ratio... 

A simplified cross-sectional view of the apparatus is illustrated in Fig. 3. The three optical siib-systems and the particle feed are mounted to a spherical frame, fixed to a base-plate via a cylindrical shaft. The light sources of the optical subsystems are respectively mounted in the head of the upper protrusions. The sensors, electrical transducers and filters are located in the arms below. The light sources are fed from a stabilized power supply. 

Calibration cell (shown in Figure 7.1b). An electrical calibration may be performed using a stabilized power supply (current generator), a high-accuracy resistor, a precision voltmeter and an electronic chronometer. Very high absolute tolerance resistors (0.01-0.001%) with low temperature coefficient are available, for example from Vishay-SFERNICE, France. 

A current-stabilized power supply (0-5 V 0-100 mA) is connected to the electrodes. The current is raised from 10 to 30 mA in the course of a linear sweep or may be raised in five steps. The time of electrolysis is 120 min, corresponding to a total charge transfer of 40 mA h. After electrolysis, the silver content of the electrolyte will have decreased by 20% and the removed Ag"- cations will have been replaced by protons. Increasing the electrolysis time is not recommended for the deposited AgjOj will dissolve as the acid concentration becomes too high. The yield of AgjOj is 50 mg per charge. 

---