Computer controlled current source

A measurement setup is build to verify the calculated production of gas during electrolysis according to eq 9. A computer controlled current source (CCCS) is used for electrolysis. The current source is equipped with two current ranges, 0-100 pA and 0-2 mA. The connection holes of the reservoirs are sealed with epoxy (Araldit). The calibration system is then immersed in an electrolyte solution. The electrolyte consists of a 200 mM KNO3 solution to which some detergent (Tween 20) is added. Using a vacuum system, air inside the calibration system is replaced by the electrolyte solution. 

Figure 12. The measurement set-up, consisting of a computer controlled current source (cccs) to evoke gas bubbles by electrolysis and a ccd camera to monitor the fluid displacement.

The instrumentation employed by Stapleton and Bowie was an ion cyclotron resonance mass spectrometer that had been modified to permit computer control of all drift voltages and to allow direct reading of the ion transit time (typically 10 to 10 seconds) similar to that described by McMahon and Beauchamp An emission current of about 0.2 microampere and a nominal 70 eV electron beam produced ion currents of 10 to 10 A at source pressures of approximately 10 Torr. The mass spectra were measured by magnetic field modulation. 

All electrical measurements were p>erformed under nitrogen in the glove box. The current-voltage (1-V) characteristics were recorded by a computer controlled Keithley 236 source-measure unit (SMU). When the devices were tested for the first time without any prior heat treatment, their behavior was just like that of a PLED with A1 as cathode the tum-on voltage was over 6 volts with relatively low brightness and low efficiency even at high... 

All electrical measurements were performed under nitrogen in the glove box. The current-voltage characteristics were recorded by a computer controlled Keithley 236 source-measure unit. 

In order to commercialize ion beam methods outside the semiconductor Held the development of new implanters with high-current ion sources 72-75 has been continued in recent years, and operation of such machines has been simplified by computer control [7b. 77]. In the meantime the Danfysik machine is the only commercially available implanter with computer control on the market in Europe [78]. 

Figure 3. Schematic of instrumentation used for measuring the optical response of dye/superconductor structures (A) temperature controller, (B) current source, (C) lock-in amplifier, (D) mechanical chopper, (E) chopper controller, (F) optical interface, (G) monochromator, (H) computer controller, printer, (J) xy-plotter.

All of the areas of proof described above provide evidence concerning the current operations of the computer systems in place, but can those same controls be expected to continue to function over time Certainly a trend of control provides some presumption, and annual SOP review procedures provide a degree of assurance, but the most significant evidence of system reliability lies internal to the software and is documented only through a review of that source code itself. 

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