摘要:
A method for calibrating a test instrument having an initial output voltage level and an open output relay can include programming the test instrument for a certain current level, starting a timer, and stopping the timer (responsive to the test instrument entering compliance) to determine a time interval. The method can also include determining whether the time interval is within a desired range.
摘要:
A switching power supply can include multiple power MOSFETs that receive an initial gate drive waveform comprising a fast slew rate region having a negative slope and a slow slew rate region also having a negative slope. The MOSFETs can turn off during the slow slew rate region of the initial gate drive waveform.
摘要:
Bias tees, according to certain embodiments of the present invention, include switches (645, 650) in the AC signal path, the DC signal path, or both, to improve the capability of the bias tees to be used for high impedance AC measurement, low current DC measurement, or both. Optical control (670, 675) of the switches, as well as control of the switches using a DC bias present within the AC signal input to the bias tee, is described. Including a set of diodes into the DC signal path, rather than a switch, provides enhanced capability of the bias tee to be used for high impedance AC measurements.
摘要:
A high voltage protection module can include a housing having two chambers (120,122) and a wall (114) separating the chambers (120,122). The wall (114) can have a hole (115) through which a conductive element (105) can pass to electrically couple an input (104) with an output (110). The conductive element (105) can be configured to break or fuse with the hole (115) responsive to a high voltage event at the input (104).
摘要:
Apparatus is provided for use in detecting the peak voltage applied to a radiation source operating at an unknown input voltage. The apparatus includes a set of radiation absorbing filters including a first filter which includes a first element that exhibits a known K-absorption edge and a second filter constructed of a second element so that the filters exhibit essentially the same radiation absorption characteristics below the K-absorption edge of the first filter. The filters are adapted to be positioned so as to be irradiated by the radiation source so that the radiation impinges upon a surface of each filter and is partially absorbed as it passes therethrough so as to exit therefrom as attenuated radiation. A detector, such as X-ray film or a pair of photodiodes, is positioned for receiving the attenuated radiation passed by the first and second filters and provides an output indication when the radiation passed by the filters is differently attenuated. This is indicative that the known K-absorption edge of the first filter has been exceeded, thereby providing an indication as to the magnitude of the voltage applied to the radiation source.
摘要:
A method for producing sampled data, which as the requested sampling period is increased, each sample is the average of an increasing number of ADC samples such that a maximum number of ADC samples are evenly space across the sample period. The method can include choosing one of multiple ADC with varying speed versus resolution capabilities to further increase the quality of the sampled data as the sampling period increases.
摘要:
A device with low dielectric absorption includes a printed circuit board (PCB) (300), a component connection area (302) including a first conductor (310) layered on a top surface of the component connection area and a second conductor (316) layered on a bottom surface of the component connection area, an aperture (304) surrounding the component connection area, a low-leakage component (306, 308) connecting the component connection area to the PCB across the aperture, and a guard (314, 318) composed of a third conductor (314) at least substantially surrounding the aperture on a top surface of the PCB and a fourth conductor (318) at least substantially surrounding the aperture on a bottom surface of the PCB.
摘要:
An active shunt ammeter for measuring current flowing through a device under test (DUT) and method are disclosed. The active shunt ammeter includes an input configured to receive an input signal having a frequency within a frequency band and representing the current flowing through the DUT. An output is configured to generate an output voltage representing the current flowing through the DUT. The active shunt ammeter also includes a gain circuit having an amplifier with a gain characteristic that varies respect to frequency within the frequency band and a feedback element having an impedance coupled from an output of the gain circuit to a negative input of the gain circuit, the feedback element impedance being configured to change with frequency to correlate with the amplifier gain characteristic such that the feedback element impedance divided by the amplifier gain over the frequency band has minimal frequency dependency.
摘要:
A dose distribution analyzer (20) and methods for providing a radiation dose map indicating energy of a spacially variable radiation pattern beamed onto a dose map radiation dosimeter (10). The radiation dosimeter (10) is exposed to a proposed spacially variable radiation pattern such as used in a phantom patient for patient radiation dose treatment verification. The dosimeter (10) is subsequently analyzed by the dose distribution analyzer (20). Such analyzer includes a phosphor stimulator (53), an image forming subsystem (38), and an image sensor (37). A dosimeter holder (32) holds the dosimeter near the phosphor stimulator (53). A system controller (22) is connected to receive image data from the image sensor (37) while the dosimeter (10) is stimulated. The controller (22) utilizes the image data to derive a radiation dose map which indicates the distribution of radiation in the spacially variable radiation pattern which strikes the dosimeter (10).
摘要:
Apparatus is provided for use in detecting the input voltage applied to a radiation source (10) operating at an unknown voltage within a given voltage range. The apparatus includes a set of radiation absorbing filters (F1, F2) including a first filter which includes a first chemical element and a second filter which includes a second chemical element. These elements are chosen so that the filters exhibit different radiation absorption characteristics within the given voltage range. The filters are adapted to be positioned so that the first and second filters are irradiated by the radiation source (10) with the radiation (18) impinging upon a surface of each filter and partially absorbed thereby as it passes therethrough so as to exit therefrom as attenuated radiation. A detector (20) receives the attenuated radiation passed by the first and second filters and provides first and second signals (I₁, I₂) having magnitudes which vary with the attenuated radiation respectively passed by the first and second filters. A ratio (34) is determined as to the magnitude of the first signal to that of the second signal with the magnitude of the ratio varying with that of the input voltage. At least one of the first and second elements (F1, F2) exhibits a known K absorption edge within the given voltage range. Consequently as the input voltage is increased to exceed the known K absorption edge that chemical element exhibits a greater attenuation characteristic to extend the useful range of the relationship of the magnitude of the ratio and the input voltage.