DIY数字电桥说明 - EEVblog.DOC

DIY digital bridge Description Xu Jianwei Putian TenthI. Overview: Crystal radio play, most of the components needed DIY, it is necessary to know the parameters element. Since no elements of DIY nominal technical parameters. For example, the devices need to know the characteristics of the reactance of the resonance means, detection means, an antenna, an earphone, transformers and the like. Wherein Q, frequency parameters can be used to solve the problem, the parameter Q for the low frequency is difficult to measure. To solve this problem, we believe that the LCR digital bridge capable. 稤esign goals: 1, it is possible to accurately measure the reactor L, C, R, accuracy of better than 0.5%, if the manual shift by calibration, accuracy of better than 0.3% 2, drawing easy, Jian Jie circuit, easy to make, cost should be properly controlled. So that it has more value and amateur DIY research value, and to learn details LCR bridge, through the design principle, DIY. The basic characteristics of the Ben LCR table AD converter Word Count: about 1000 words, using the oversampling technique, the effective resolution of approximately 2000 words Measurement method: quasi-bridge assay, the measurement principle is similar to the proportion of resistance measurement. The main measuring range: 0.5 to 1 megohm Europe, precision 0.5% (theoretical), comparing the measured impedance, no more than 0.3% Effective measuring range: 2 to 10 milliohms megohm, minimum resolution 1 milli-ohm Series residual error: 2 milliohms, when this error is not negligible low resistance measurements Parallel residual error: 50M Europe, this high-impedance measurement error is not negligible Q error:?.003 (Q 0.5), Q / 300 (Q 2, the relative error, simple algorithm), the other by about 0.5% Estimation, D error:?.003 (D 0.5), D / 300 (D 2, the relative error, simple algorithm), the other by about 0.5% Estimation, Note: Q = 1 / D Test signal amplitude: peak 200mV (100Hz), 180mV (1kHz), 140mV (7.