Abstract: A modeling compound and methods for making the same are described. The modeling compound, in some embodiments, comprises about 20% to about 40% by weight starch-based binder, and about 0.15% to about 1.2% by weight microspheres dispersed throughout the compound.

Abstract: The thermionic valve tester (10) has a casing (11) and three valve sockets (12) each of which is adapted to receive and has terminals for connection with the electrode pins of different types of thermionic valves. The thermionic valve tester (10) also has a display (13) comprising a series of LED lights, three user operated buttons (16), and a single power supply socket or terminal (14) which supplies power to all components of the valve tester and which is adapted for connection to a low voltage DC power supply lead. Internally, the thermionic valve tester (10) has a plurality of voltage regulators each with a switchable connection to at least one valve electrode terminal of the valve sockets (12) and a memory in which is stored the tests and the performance criteria for different types of thermionic valves.

Abstract: Methods for preventing blackening of a gas filled arc tube of a mercury vapour discharge lamp. Lamp voltage and slope, as well as lamp current and slope are analyzed to determine the state of mercury saturation of the gas in the arc tube. A first control signal is sent to alter the lamp power and a second control signal is sent to alter the level of cooling of the lamp according to the state of mercury saturation. Methods for driving a mercury vapour discharge lamp using a monitoring arrangement and analyzing unit to dynamically control the lamp power and the level of cooling of the lamp are described.

Abstract: Apparatus and methods for measuring cathode fall in fluorescent lamps are disclosed. Together with measurements of cathode temperature, such measurements of cathode fall may inform a determination of cathode heater voltage as a function of discharge current (i.e., a cathode-heating-profile) that avoids both sputtering and excess-evaporation.

Abstract: A moldable composition comprising a polar polymeric resin, present in an amount ranging from 0.5-15% by weight, a filler, present in an amount up to 50% by weight, a thickening agent, present in an amount ranging from 0.1-3% by weight, a humectant, present in an amount up to 30% by weight, and water, present in an amount ranging from 20-70% by weight. Also provided is a method of making the composition as described.

Abstract: The microwave generator with use of a magnetron comprises a microwave detector for detecting microwave output from the magnetron and a filament life diagnostic circuit for judging the life of filament of the magnetron by decreasing an input power to a filament of the magnetron from a normal state of the magnetron while monitoring the microwave output from the magnetron by the microwave detector, comparing the input power in the normal state of the magnetron with that just before the magnetron becomes unstable and judging the filament life based on the difference between the input power of the normal state and that just before the unstable state.

Abstract: An apparatus measures the operational parameters of a vacuum tube that has an anode, a cathode, a grid and a filament. A source of a bias potential for the anode is included along with a generator that produces a series of pulse at each of a plurality of voltage levels. A resistor couples the pulses to the vacuum tube grid and another resistor couples the cathode to ground potential. A voltmeter sequentially measures the voltages on the grid, the anode, the cathode, and across the resistors. From these voltage measurements, the system computes the levels of the grid current and the filament current. These parameters of the tube are displayed graphically for use in comparing the performance of different tubes.

Abstract: A method of testing an electron discharge device incorporating a cathode electrode heated by bombardment of electrons emitted by a heater electrode so that selected parameters of such device may be determined without requiring that such device be operational, the method in particular including the steps of causing the cathode electrode to be brought to operating temperature within a short period of time and determining that the current due to electrons bombarding the cathode electrode is within predetermined limits.

Abstract: In a circuit for an ionization vacuum gauge having a thermionic filament, a control circuit receptive of a control current for controlling the filament and a switch for applying the control current to the control circuit, a circuit is provided for indicating a filament interruption independent of the state of the switch. The circuit includes at least one resistor by-passing the switch to provide a continuous sensing current to the filament and a detector for detecting the interruption in the sensing current and for indicating such an interruption.