Agilent HP Journal - LCR Meter article Dec77 free download

File name HP Journal - LCR Meter article Dec77.pdf

Microprocessor control broadens the capabilities of this speedy LCR meter and makes it readily adaptable to BCD or HP-IB automatic systems. by Masahiro Yokokawa and Keiki Kanafuji F OR AN ELECTRONIC CIRCUIT to meet perfor- quency, and connect the component to the test termi- mance goals, the values of the components used nals. The instrument automatically switches to the in assembling the circuit must fall within certain correct measurement range, selects the preferred cir- ranges, some wide, some narrow. Despite increasing cuit mode, and presents results on the 31/2digit dis- sophistication in the design and manufacture of pas- plays in about 250 ms without any time-consuming sive circuit components, differences between sup- balancing adjustments. The user, however, can have posedly identical components do exist and the ranges full manual cont:rol of the instrument at any time of values encountered often exceed acceptable limits. simply by pressing the appropriate front-panel Thus, most electronic laboratories, quality-control pushbuttons. labs, and receiving departments are equipped to mea- The front-panel[ control arrangement is similar to sure the actual values of the components with which manually controlJled instruments (see Fig. 1) speed- they are concerned, a process that is not only time ing familiarizatio][l with the instrument. As a further consuming, but one that often introduces errors of its safeguard agains:t the possibility of unintentional own. To speed these measurements, and reduce the missettings, the RANGE and CIRCUIT MODEfunctions human errors that arise in this activity, late-model automatically revlert to AUTOwhenever the L, C, or R LCR meters, such as the Model 4261A described in a function keys are pressed after manual modes have recent issue of the HP Journal,1 have been designed been in use. Since most measurements made with this with a high degree of automation. kind of instrument are made on capacitors, when it is A new LCR meter, Model 4262A, uses a micro- first turned on the new LCR meter automatically sets processor to further automate procedures while in- itself for the CDmode using a I-kHz test frequency. creasing the instrument's capabilities without incur- ring significantly greater costs. To measure the value Enhanced Capability of a passive component with this instrument (Fig. 1), Besides autoranging, self-triggering, and automatic ~it is only necessary to select the measurement func- selection of the appropriate circuit mode (series or tion and loss parameter-i.e., resistance (R),capaoi- parallel), the mil::roprocessor brings several othen tance (C),or inductance (L),and dissipat