Abstract: In a monolithic integrated circuit, on-chip trimming is implemented by connecting a zener diode across each element of a plural element trimmable resistor. Adjacent diodes are connected back to back and a pair of conventional bonding pads connected thereto. In trimming, when it is desired to short out one of the trimmable elements, the associated diode is subjected to an overload pulse by means of test probes applied to the bonding pads. Since the diodes are connected back to back, the pulse polarity will determine which diode is overloaded in the reverse bias condition. Thus, the trimmable element to be shorted is determined by pulse polarity and only one bonding pad is needed for each pair of trimmable elements.

Abstract: An electrostatic voltmeter for measuring the electrostatic potential on a photosensitive drum has a detector capacitively coupled to the drum for providing an output signal in response to the potential on the drum. An AC voltage source is coupled in circuit with the drum and the detector for applying an AC signal across the surface-to-detector capacitance. Circuitry coupled to the detector determines the detector gain in response to the value of the AC component of the output signal and the value of the applied AC signal. The product of the reciprocal of the detector gain and the value of the DC component of the output signal is representative of the electrostatic potential on the surface.

Abstract: Placement of cylindrical magnets inside of a cylindrical cathode comprising a source of depositing material for sputter depositing of the material upon the interior surface of a substantially cylindrical workpiece, results in improved deposition rates, low power requirements, low workpiece temperatures and purity and cohesiveness in the deposited layer of material.

Abstract: A solar heat collector constructed from transparent material utilizes a circulating absorptive fluid medium to collect solar energy. The collector comprises a plurality of cascaded fluid reservoirs, each reservoir having a self-draining feature active during a stagnant condition.

Abstract: An averaging frequency counter for determining the frequency of recurrence of input signals has an event counter for counting a number of the input signals, a gate counter for counting a number of time intervals during which the input signals are counted, and a time interval measurement circuit for measuring the cumulative duration of the time intervals. A systematic error associated with the measurement of the duration of each time interval is determined during an application of a calibrated frequency to the averaging frequency counter by dividing a calculated total time error by the number of time intervals. The systematic error is subsequently used to correct a measurement of an unknown frequency during an application of the unknown frequency to the averaging frequency counter by subtracting a product of the number of the time intervals and the systematic error from the cumulative duration.

Abstract: An epoxy/aluminum sandwich is used to mount a glass lens rigidly within a stainless steel cell without subjecting the glass lens to stresses caused by differences between the temperature coefficients of expansion of the glass lens and the stainless steel cell.

Abstract: A voltmeter having multiple voltage ranges comprises substantially linear elements such that the transfer functions of the elements can be independently measured and logically combined to derive the transfer function of a given combination of elements configured to obtain a given voltage range.

Abstract: A tacheometer utilizes a gallium arsenide laser diode in a phase shifting distance encoder, a sinusoidal interpolator in a phase shifting shaft angle encoder, a mercury pool in a phase shifting two axis off-level encoder, a shared phase to digital decoder and a digital processor, to measure angles and distances corrected for off-level, speed of light variations, refraction and the earth's curvature.

Abstract: An oscilloscope has an additional vertical display mode to enable the display of the trigger signal, activating the sweep generating circuit, simultaneously with the display of the normal vertical channels. The triggering source, level, slope and subtle time relationships can be verified and examined continuously and concurrently with the measurements upon the normal vertical channels. The displayed trigger signal is in correct time relationship with the normal vertical channels and the trigger level threshold is identified.

Abstract: A tacheometer utilizes a gallium arsenide laser diode in a phase shifting distance encoder, a sinusoidal interpolator in a phase shifting shaft angle encoder, a mercury pool in a phase shifting two axis off-level encoder, a shared phase to digital decoder and a digital processor, to measure angles and distances corrected for off-level, speed of light variations, refraction and the earth's curvature. A reflecting telescope is coupled to the shaft angle encoder and is incorporated in both the phase shifting distance encoder and the alignment system. The reflecting telescope has a doublet objective lens with an embedded secondary reflective surface facing a primary mangin mirror. A biconcave element of the doublet objective lens also functions as a corrector for the secondary reflective surface. A compact objective lens system is thus realized, having minimal interference between the corrector for the secondary reflective surface and the optical path through the doublet objective lens.

Abstract: A method and circuit for detecting spurious transitions ("glitches", herein) upon a digital signal utilizes a test for such a glitch condition dependent upon the digital signal level and upon the polarity of subsequent transitions within a discrete sampling period to allow for the detection of any type of glitch. A simultaneous display for the sampled digital data and for the detected glitch information further allows a convenience to an operator analyzing the data. Further, the glitch detector is used as a trigger for retrieving selected portions of the sampled digital signal.

Abstract: A programmable transfer gate array generates control signals as functions of input variables in a digital logic circuit by using two-phase logic requiring no quiescent D.C. power consumption.

Abstract: A digital pattern triggering circuit combines an addressable memory and a processor. Input data patterns address corresponding memory elements whereby data previously stored in the memory by the processor is accessed, providing an indication of whether a preselected data pattern has occurred.

Abstract: A circuit for performing dual slope integration to provide a digital measurement of an input voltage of either positive or negative polarity employs a single source of reference potential in combination with a switchable resistive network as a source of reference current.

Abstract: A digital data decoder for recovering data from magnetic media utilizes a phase-locked loop incorporating a dual slope detecting circuit and a window margin test so as to allow for higher density data and for quality verification of the data without the use of high frequency components.

Abstract: Half-adder logic modules employing separate summing and carry circuitry are used in the construction of a modular binary half-adder. Carry bits of less significant digits are calculated independent of and prior to the calculation of corresponding sum bits, thus allowing rapid propagation of such carry bits to more significant digits and subsequent parallel summation of the sum bits using the carry bits previously calculated.

Abstract: A circuit is described which compensates for variation in the threshold voltage of Insulated Gate Field Effect Transistors (IGFETs) in an integrated circuit by modulating the substrate voltage in response to the variation of the threshold voltage from a desired nominal value.

Abstract: An improved and simplified method of fabricating field effect transistors in metal oxide semiconductor integrated circuits advantageously employs the differential growth rate, under certain temperature conditions, between oxide on silicon wherein phosphorous has been diffused, and on silicon without such diffusion. The improved method of fabrication reduces the number of fabrication steps required, while simultaneously producing field effect transistors with superior operation speeds.

Abstract: This is an ion-producing source having a distinct chemical ionization configuration and a distinct electron impact configuration. In this source, a hollow chamber including an ion source and a source of sample molecules receives a hollow, slidable cylindrical member having a chemical ionization chamber within it. Orifices in the chamber and the cylindrical member connect the chemical ionization source chamber to the electron source and to the sample molecule source when the cylindrical member is pulled to one position. When the cylindrical member is pulled to another position, the slidable cylindrical member and the inside walls of the chamber define the ionization region to which the electron source and the sample molecule source are directly connected. By moving the cylindrical member, the ionization source can be changed from a chemical ionization source to an electron impact source.